Aeronautical Terms
100-Hour Inspection
An inspection, identical in scope to an annual inspection. Must be conducted every 100 hours of flight on aircraft of under 12,500 pounds that are used for hire.
14 CFR part 121
The Federal regulations governing domestic, flag, and supplemental operations.
14 CFR part 135
The Federal regulations governing Commuter and On-Demand Operations.
14 CFR part 43
The Federal regulations governing Maintenance, Preventive Maintenance, Rebuilding, And Alteration
14 CFR Part 61
The Federal regulations governing Pilots, Flight Instructors, And Ground Instructors.
14 CFR Part 91
The Federal regulations governing General Operating And Flight Rules
14 CFR–Title 14 of the Code of Federal Regulations
The federal aviation regulations governing the operation of aircraft, airways, and airmen.
180 Degrees Autorotation
Initiated from a downwind heading and is commenced well inside the normal traffic pattern. “Go around” may not be possible during the latter part of this maneuver.
360 Overhead
Overhead Maneuver.
Abbreviated IFR Flight Plans
An authorization by ATC requiring pilots to submit only that information needed for the purpose of ATC. It includes only a small portion of the usual IFR flight plan information. In certain instances, this may be only aircraft identification, location, and pilot request. Other information may be requested if needed by ATC for separation/control purposes. It is frequently used by aircraft which are airborne and desire an instrument approach or by aircraft which are on the ground and desire a climb to VFR-on-top.
Abeam
An aircraft is “abeam” a fix, point, or object when that fix, point, or object is approximately 90 degrees to the right or left of the aircraft track. Abeam indicates a general position rather than a precise point.
Abeam Fix
A fix, NAVAID, point, or object positioned approximately 90 degrees to the right or left of the aircraft track along a route of flight. Abeam indicates a general position rather than a precise point.
Abort
To terminate a preplanned aircraft maneuver; e.g., an aborted takeoff.
Absolute accuracy
The ability to determine present position in space independently, and is most often used by pilots.
Absolute Altitude
The vertical distance of an airplane above the terrain, or above ground level (AGL).
Absolute Ceiling
The altitude at which a climb is no longer possible.
Absolute instability
A state of a layer within the atmosphere in which the vertical distribution of temperature is such that an air parcel, if given an upward or downward push, wiII move away from its initial level without further outside force being applied.
Absolute pressure
Pressure measured from the reference of zero pressure, or a vacuum.
Absolute temperature scale
Kelvin Temperature Scale. A temperature scale with zero degrees equal to the temperature at which all molecular motion ceases, i.e., absolute zero (0° K = -273° C); the Kelvin degree is identical to the Celsius degree; hence at standard sea level pressure, the melting point is 273° K and the boiling point 373° K.
Absolute vorticity
The rotation of the Earth imparts vorticity to the atmosphere; absolute vorticity is the combined vorticity due to this rotation and vorticity due to circulation relative to the Earth (relative vorticity).
Abstractions
Words that are general rather than specific. Aircraft is an abstraction; airplane is less abstract; jet is more specific; and jet airliner is still more specific.
Accelerate-Go Distance
The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and continue the takeoff on the remaining engine(s). The runway required includes the distance required to climb to 35 feet by which time V2 speed must be attained.
Accelerate-Stop Distance
The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and abort the takeoff and bring the airplane to a stop using braking action only (use of thrust reversing is not considered).
Accelerate-Stop Distance Available
The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.
Accelerate-Stop Distance Available (ASDA)
The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.
Accelerate-Stop Distance Available [ICAO]
The length of the take-off run available plus the length of the stopway if provided.
Acceleration
Force involved in overcoming inertia, and which may be defined as a change in velocity per unit of time.
Acceleration error
A magnetic compass error apparent when the aircraft accelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward North.
Accelerometer
A part of an inertial navigation system (INS) that accurately measures the force of acceleration in one direction.
Accessories
Components that are used with an engine, but are not a part of the engine itself. Units such as magnetos, carburetors, generators, and fuel pumps are commonly installed engine accessories.
Acknowledge
Let me know that you have received my message.
Acknowledge [ICAO]
Let me know that you have received and understood this message.
Acrobatic Flight
An intentional maneuver involving an abrupt change in an aircraft’s attitude, an abnormal attitude, or abnormal acceleration not necessary for normal flight. (Refer to 14 CFR Part 91.
Acrobatic Flight [ICAO]
Maneuvers intentionally performed by an aircraft involving an abrupt change in its attitude, an abnormal attitude, or an abnormal variation in speed.
ACS
Airman Certification Standards
Active Runway
Runway In Use/Active Runway/Duty Runway.
Actual Calculated Landing Time
ACLT is a flight’s frozen calculated landing time. An actual time determined at freeze calculated landing time (FCLT) or meter list display interval (MLDI) for the adapted vertex for each arrival aircraft based upon runway configuration, airport acceptance rate, airport arrival delay period, and other metered arrival aircraft. This time is either the vertex time of arrival (VTA) of the aircraft or the tentative calculated landing time (TCLT)/ACLT of the previous aircraft plus the arrival aircraft interval (AAI), whichever is later. This time will not be updated in response to the aircraft’s progress.
Actual Navigation Performance (ANP)
A measure of the current estimated navigational performance. Also referred to as Estimated Position Error (EPE).
Additional Services
Advisory information provided by ATC which includes but is not limited to the following: a. Traffic advisories. b. Vectors, when requested by the pilot, to assist aircraft receiving traffic advisories to avoid observed traffic. c. Altitude deviation information of 300 feet or more from an assigned altitude as observed on a verified (reading correctly) automatic altitude readout (Mode C). d. Advisories that traffic is no longer a factor. e. Weather and chaff information. f. Weather assistance. g. Bird activity information. h. Holding pattern surveillance. Additional services are provided to the extent possible contingent only upon the controller’s capability to fit them into the performance of higher priority duties and on the basis of limitations of the radar, volume of traffic, frequency congestion, and controller workload. The controller has complete discretion for determining if he/she is able to provide or continue to provide a service in a particular case. The controller’s reason not to provide or continue to provide a service in a particular case is not subject to question by the pilot and need not be made known to him/her.
Adiabatic cooling
A process of cooling the air through expansion. For example, as air moves up slope it expands with the reduction of atmospheric pressure and cools as it expands.
Adiabatic heating
A process of heating dry air through compression. For example, as air moves down a slope it is compressed, which results in an increase in temperature.
Adiabatic process
The process by which fixed relationships are maintained during changes in temperature, volume, and pressure in a body of air without heat being added or removed from the body.
Adjustable Stabilizer
A stabilizer that can be adjusted in flight to trim the airplane, thereby allowing the airplane to fly hands-off at any given airspeed.
Adjustable-pitch propeller
A propeller with blades whose pitch can be adjusted on the ground with the engine not running, but which cannot be adjusted in flight. Also referred to as a ground adjustable propeller. Sometimes also used to refer to constant-speed propellers that are adjustable in flight.
Administrator
The Federal Aviation Administrator or any person to whom he has delegated his authority in the matter concerned.
Advection
The horizontal transport of air or atmospheric properties. In meteorology, sometimes referred to as the horizontal component of convection.
Advection fog
Fog resulting from the transport of warm, humid air over a cold surface.
Adverse Loaded CG Check
A weight and balance check to determine that no condition of legal loading of an aircraft can move the CG outside of its allowable limits.
Adverse Yaw
A condition of flight in which the nose of an airplane tends to yaw toward the outside of the turn. This is caused by the higher induced drag on the outside wing, which is also producing more lift. Induced drag is a by-product of the lift associated with the outside wing.
Advise Intentions
Tell me what you plan to do.
Advisory
Advice and information provided to assist pilots in the safe conduct of flight and aircraft movement.
Advisory Frequency
The appropriate frequency to be used for Airport Advisory Service.
Advisory Service
Advice and information provided by a facility to assist pilots in the safe conduct of flight and aircraft movement.
Aerial Refueling
A procedure used by the military to transfer fuel from one aircraft to another during flight.
Aerodrome
A defined area on land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure, and movement of aircraft.
Aerodrome Beacon [ICAO]
Aeronautical beacon used to indicate the location of an aerodrome from the air.
Aerodrome Control Service [ICAO]
Air traffic control service for aerodrome traffic.
Aerodrome Control Tower [ICAO]
A unit established to provide air traffic control service to aerodrome traffic.
Aerodrome Elevation [ICAO]
The elevation of the highest point of the landing area.
Aerodrome Traffic Circuit [ICAO]
The specified path to be flown by aircraft operating in the vicinity of an aerodrome.
Aerodynamic Ceiling
The point (altitude) at which, as the indicated airspeed decreases with altitude, it progressively merges with the low speed buffet boundary where pre-stall buffet occurs for the airplane at a load factor of 1.0 G.
Aerodynamic coefficients
Non-dimensional coefficients for aerodynamic forces and moments.
Aerodynamics
The science of the action of air on an object, and with the motion of air on other gases. Aerodynamics deals with the production of lift by the aircraft, the relative wind, and the atmosphere.
Aeronautical Beacon
A visual NAVAID displaying flashes of white and/or colored light to indicate the location of an airport, a heliport, a landmark, a certain point of a Federal airway in mountainous terrain, or an obstruction.
Aeronautical chart
A map used in air navigation containing all or part of the following: topographic features, hazards and obstructions, navigation aids, navigation routes, designated airspace, and airports.
Aeronautical Chart [ICAO]
A representation of a portion of the earth, its culture and relief, specifically designated to meet the requirements of air navigation.
Aeronautical decision-making (ADM)
A systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances.
Aeronautical Information Manual (AIM)
A primary FAA publication whose purpose is to instruct airmen about operating in the National Airspace System of the U.S. It provides basic flight information, ATC Procedures and general instructional information concerning health, medical facts, factors affecting flight safety, accident and hazard reporting, and types of aeronautical charts and their use.
Aeronautical Information Publication (AIP) [ICAO]
A publication issued by or with the authority of a State and containing aeronautical information of a lasting character essential to air navigation.
Affective domain
A grouping of levels of learning associated with a person’s attitudes, personal beliefs, and values which range from receiving through responding, valuing, and organization to characterization.
Affirmative
Yes.
AGL Altitude
Altitude expressed in feet measured above ground level.
Agonic line
An irregular imaginary line across the surface of the Earth along which the magnetic and geographic poles are in alignment, and along which there is no magnetic variation.
Ailerons
Primary flight control surfaces mounted on the trailing edge of an airplane wing, near the tip. Ailerons control roll about the longitudinal axis.
Air carrier
A person who undertakes directly by lease, or other arrangement, to engage in air transportation.
Air Carrier District Office
An FAA field office serving an assigned geographical area, staffed with Flight Standards personnel serving the aviation industry and the general public on matters related to the certification and operation of scheduled air carriers and other large aircraft operations.
Air commerce
Interstate, overseas, or foreign air commerce or the transportation of mail by aircraft or any operation or navigation of aircraft within the limits of any Federal airway or any operation or navigation of aircraft which directly affects, or which may endanger safety in, interstate, overseas, or foreign air commerce.
Air data computer (ADC)
An aircraft computer that receives and processes pitot pressure, static pressure, and temperature to calculate very precise altitude, indicated airspeed, true airspeed, and air temperature.
Air Defense Emergency
A military emergency condition declared by a designated authority. This condition exists when an attack upon the continental U.S., Alaska, Canada, or U.S. installations in Greenland by hostile aircraft or missiles is considered probable, is imminent, or is taking place.
Air Defense Identification Zone (ADIZ)
The area of airspace over land or water, extending upward from the surface, within which the ready identification, the location, and the control of aircraft are required in the interest of national security.
Air density
The mass density of the air in terms of weight per unit volume.
Air mass
In meteorology, an extensive body of air within which the conditions of temperature and moisture in a horizontal plane are essentially uniform.
Air mass classification
A system used to identify and to characterize the different air masses according to a basic scheme. The system most commonly used classifies air masses primarily according to the thermal properties of their source regions: “tropical” (T); “polar” (P); and “Arctic” or “Antarctic” (A). They are further classified according to moisture characteristics as “continental” (c) or “maritime” (m).
Air Navigation Facility
Any facility used in, available for use in, or designed for use in, aid of air navigation, including landing areas, lights, any apparatus or equipment for disseminating weather information, for signaling, for radio-directional finding, or for radio or other electrical communication, and any other structure or mechanism having a similar purpose for guiding or controlling flight in the air or the landing and takeoff of aircraft.
Air parcel
A. small volume of air, small enough to contain uniform distribution of its meteorological properties, and large enough to remain relatively self-contained and respond to all meteorological processes. No specific dimensions have been defined, however, the order of magnitude of 1 cubic foot has been suggested.
Air Route Surveillance Radar
Air route traffic control center (ARTCC) radar used primarily to detect and display an aircraft’s position while en route between terminal areas. The ARSR enables controllers to provide radar air traffic control service when aircraft are within the ARSR coverage. In some instances, ARSR may enable an ARTCC to provide terminal radar services similar to but usually more limited than those provided by a radar approach control.
Air route surveillance radar (ARSR)
Air route traffic control center (ARTCC) radar used primarily to detect and display an aircrafts position while en route between terminal areas.
Air Route Traffic Control Center
A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
Air Route Traffic Control Center (ARTCC)
A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight
Air Start
The act or instance of starting an aircraft’s engine while in flight, especially a jet engine after flameout.
Air Taxi
Used to describe a helicopter/VTOL aircraft movement conducted above the surface but normally not above 100 feet AGL. The aircraft may proceed either via hover taxi or flight at speeds more than 20 knots. The pilot is solely responsible for selecting a safe airspeed/altitude for the operation being conducted.
Air traffic
Aircraft operating in the air or on an airport surface, exclusive of loading ramps and parking areas.
Air traffic clearance
An authorization by air traffic control, for the purpose of preventing collision between known aircraft, for an aircraft to proceed under specified traffic conditions within controlled airspace.
Air traffic control
A service operated by appropriate authority to promote the safe, orderly, and expeditious flow of air traffic.
Air traffic control (ATC)
A service provided by the FAA to promote the safe, orderly, and expeditious flow of air traffic.
Air Traffic Control Clearance [ICAO]
Authorization for an aircraft to proceed under conditions specified by an air traffic control unit. Note 1: For convenience, the term air traffic control clearance is frequently abbreviated to clearance when used in appropriate contexts. Note 2: The abbreviated term clearance may be prefixed by the words taxi, takeoff, departure, en route, approach or landing to indicate the particular portion of flight to which the air traffic control clearance relates.
Air traffic control radar beacon system (ATCRBS)
Sometimes called secondary surveillance radar (SSR), which utilizes a transponder in the aircraft. The ground equipment is an interrogating unit, in which the beacon antenna is mounted so it rotates with the surveillance antenna. The interrogating unit transmits a coded pulse sequence that actuates the aircraft transponder. The transponder answers the coded sequence by transmitting a preselected coded sequence back to the ground equipment, providing a strong return signal and positive aircraft identification, as well as other special data.
Air traffic control radar beacon system (ATCRBS).
Sometimes called secondary surveillance radar (SSR), which utilizes a transponder in the aircraft. The ground equipment is an interrogating unit, in which the beacon antenna is mounted so it rotates with the surveillance antenna. The interrogating unit transmits a coded pulse sequence that actuates the aircraft transponder. The transponder answers the coded sequence by transmitting a preselected coded sequence back to the ground equipment, providing a strong return signal and positive aircraft identification, as well as other special data.
Air Traffic Control Service
Air Traffic Control.
Air Traffic Control Service [ICAO]
A service provided for the purpose of: a. Preventing collisions: 1. Between aircraft; and 2. On the maneuvering area between aircraft and obstructions. b. Expediting and maintaining an orderly flow of air traffic.
Air Traffic Control Specialist
A person authorized to provide air traffic control service.
Air Traffic Control System Command Center
An Air Traffic Tactical Operations facility responsible for monitoring and managing the flow of air traffic throughout the NAS, producing a safe, orderly, and expeditious flow of traffic while minimizing delays. The following functions are located at the ATCSCC: a. Central Altitude Reservation Function (CARF). Responsible for coordinating, planning, and approving special user requirements under the Altitude Reservation (ALTRV) concept. b. Airport Reservation Office (ARO). Responsible for approving IFR flights at designated high density traffic airports (John F. Kennedy, LaGuardia, and Ronald Reagan Washington National) during specified hours. c. U.S. Notice to Airmen (NOTAM) Office. Responsible for collecting, maintaining, and distributing NOTAMs for the U.S. civilian and military, as well as international aviation communities. d. Weather Unit. Monitor all aspects of weather for the U.S. that might affect aviation including cloud cover, visibility, winds, precipitation, thunderstorms, icing, turbulence, and more. Provide forecasts based on observations and on discussions with meteorologists from various National Weather Service offices, FAA facilities, airlines, and private weather services.
Air Traffic Service
A generic term meaning: a. Flight Information Service. b. Alerting Service. c. Air Traffic Advisory Service. d. Air Traffic Control Service: 1. Area Control Service, 2. Approach Control Service, or 3. Airport Control Service.
Air Traffic Service (ATS)
Air traffic service is an ICAO generic term meaning variously, flight information service, alerting service, air traffic advisory service, air traffic control service (area control service, approach control service, or aerodrome control service).
Air Traffic Service (ATS) route
A specified route designated for channeling the flow of traffic as necessary for the provision of air traffic services. The term “ATS route” refers to a variety of airways, including jet routes, area navigation (RNAV) routes, and arrival and departure routes. An ATS route is defined by route specifications, which may include:
(1) An ATS route designator;
(2) The path to or from significant points;
(3) Distance between significant points;
(4) Reporting requirements; and
(5) The lowest safe altitude determined by the appropriate authority.
Air Traffic Service (ATS) Routes
The term “ATS Route” is a generic term that includes “VOR Federal airways,” “colored Federal airways,” “jet routes,” and “RNAV routes.” The term “ATS route” does not replace these more familiar route names, but serves only as an overall title when listing the types of routes that comprise the United States route structure.
Air Traffic [ICAO]
All aircraft in flight or operating on the maneuvering area of an aerodrome.
Air transportation
Interstate, overseas, or foreign air transportation or the transportation of mail by aircraft.
Airborne
An aircraft is considered airborne when all parts of the aircraft are off the ground.
Airborne Delay
Amount of delay to be encountered in airborne holding.
Aircraft
A device that is used or intended to be used for flight in the air.
Aircraft altitude
The actual height above sea level at which the aircraft is flying.
Aircraft Approach Category
A grouping of aircraft based on reference landing speed (VREF), if specified, or if VREF is not specified, 1.3 Vso (the stalling speed or minimum steady flight speed in the landing configuration) at the maximum certificated landing weight.
Aircraft checkouts
An instructional program designed to familiarize and qualify a pilot to act as pilot in command of a particular aircraft type.
Aircraft Classes
AIRCRAFT CLASSES- For the purposes of Wake Turbulence Separation Minima, ATC classifies aircraft as Super, Heavy, Large, and Small as follows:
a. Super. The Airbus A-380-800 (A388) and the Antonov An-225 (A225) are classified as super.
b. Heavy- Aircraft capable of takeoff weights of 300,000 pounds or more whether or not they are operating at this weight during a particular phase of flight.
c, Large- Aircraft of more than 41,000 pounds, maximum certificated takeoff weight, up to but not including 300,000 pounds.
d. Small- Aircraft of 41,000 pounds or less maximum certificated takeoff weight.
Aircraft Conflict
Predicted conflict, within URET, of two aircraft, or between aircraft and airspace. A Red alert is used for conflicts when the predicted minimum separation is 5 nautical miles or less. A Yellow alert is used when the predicted minimum separation is between 5 and approximately 12 nautical miles. A Blue alert is used for conflicts between an aircraft and predefined airspace.
Aircraft Conflict Alert
A safety alert issued by ATC to aircraft under their control if ATC is aware of an aircraft that is not under their control at an altitude which, in the controller’s judgment, places both aircraft in unsafe proximity to each other. With the alert, ATC will offer the pilot an alternate course of action when feasible; e.g., “Traffic Alert, advise you turn right heading zero niner zero or climb to eight thousand immediately.”
Aircraft engine
An engine that is used or intended to be used for propelling aircraft. It includes turbosuperchargers, appurtenances, and accessories necessary for its functioning, but does not include propellers.
Aircraft Hazard Area
Used by air traffic control to segregate air traffic from a launch vehicle, reentry vehicle, amateur rocket, jettisoned stages, hardware, or falling debris generated by failures associated with any of these activities. An AHA is designated via NOTAM as either a TFR or stationary altitude reservation (ALTRV). Unless otherwise specified, the vertical limits of an AHA are from the surface to unlimited.
Aircraft List (ACL)
A view available with URET that lists aircraft currently in or predicted to be in a particular sector’s airspace. The view contains textual flight data information in line format and may be sorted into various orders based on the specific needs of the sector team.
Aircraft Logbooks
Journals containing a record of total operating time, repairs, alterations or inspections performed, and all Airworthiness Directive (AD) notes complied with. A maintenance logbook should be kept for the airframe, each engine, and each propeller.
Aircraft Specifications
Documentation containing the pertinent specifications for aircraft certificated under the CARs.
Aircraft Surge Launch And Recovery
Procedures used at USAF bases to provide increased launch and recovery rates in instrument flight rules conditions. ASLAR is based on: a. Reduced separation between aircraft which is based on time or distance. Standard arrival separation applies between participants including multiple flights until the DRAG point. The DRAG point is a published location on an ASLAR approach where aircraft landing second in a formation slows to a predetermined airspeed. The DRAG point is the reference point at which MARSA applies as expanding elements effect separation within a flight or between subsequent participating flights. b. ASLAR procedures shall be covered in a Letter of Agreement between the responsible USAF military ATC facility and the concerned Federal Aviation Administration facility. Initial Approach Fix spacing requirements are normally addressed as a minimum.
Aircraft [ICAO]
Any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the earth’s surface.
Airfoil
An airfoil is any surface, such as a wing, propeller, rudder, or even a trim tab, which provides aerodynamic force when it interacts with a moving stream of air.
Airframe
The fuselage, booms, nacelles, cowlings, fairings, airfoil surfaces (including rotors but excluding propellers and rotating airfoils of engines), and landing gear of an aircraft and their accessories and controls.
Airman Certification Standards (ACS)
An FAA published list of standards which must be met for the issuance of a particular pilot certificate or rating. FAA inspectors and designated pilot examiners use these standards when conducting pilot practical tests and flight instructors should use the ACS while preparing applicants for practical tests.
Airmanship
A sound acquaintance with the principles of flight, the ability to operate an airplane with competence and precision both on the ground and in the air, and the exercise of sound judgment that results in optimal operational safety and efficiency.
Airmanship Skills
The skills of coordination, timing, control touch, and speed sense in addition to the motor skills required to fly an aircraft.
Airmen’s Meteorological Information
AIRMET.
Airmen’s Meteorological Information (AIRMET)
In-flight weather advisories concerning weather phenomena of operational interest to all pilots and especially to pilots of aircraft not approved for flight in icing conditions. An AIRMET concerns weather of lesser severity than that covered by an advisory of significant meteorological information (SIGMET) or a convective SIGMET. AIRMETs may include advisories of moderate icing.
AIRMET
In-flight weather advisories issued only to amend the area forecast concerning weather phenomena which are of operational interest to all aircraft and potentially hazardous to aircraft having limited capability because of lack of equipment, instrumentation, or pilot qualifications. AIRMETs concern weather of less severity than that covered by SIGMETs or Convective SIGMETs. AIRMETs cover moderate icing, moderate turbulence, sustained winds of 30 knots or more at the surface, widespread areas of ceilings less than 1,000 feet and/or visibility less than 3 miles, and extensive mountain obscurement.
Airplane
An engine-driven fixed-wing aircraft heavier than air, that is supported in flight by the dynamic reaction of the air against its wings.
Airplane Flight Manual (AFM)
A document developed by the airplane manufacturer and approved by the Federal Aviation Administration (FAA). It is specific to a particular make and model airplane by serial number and it contains operating procedures and limitations.
Airplane Owner/ Information Manual
A document developed by the airplane manufacturer containing general information about the make and model of an airplane. The airplane owner’s manual is not FAA-approved and is not specific to a particular serial numbered airplane. This manual is not kept current, and therefore cannot be substituted for the AFM/POH.
Airplane Owner/Information Manual
A document developed by the airplane manufacturer containing general information about the make and model of an airplane. The airplane owner’s manual is not FAA approved and is not specific to a particular serial numbered airplane. This manual is not kept current, and therefore cannot be substituted for the AFM/POH.
Airport
An area of land or water that is used or intended to be used for the landing and takeoff of aircraft, and includes its buildings and facilities, if any.
Airport Advisory Area
The area within ten miles of an airport without a control tower or where the tower is not in operation, and on which a Flight Service Station is located.
Airport Arrival Rate (AAR)
A dynamic input parameter specifying the number of arriving aircraft which an airport or airspace can accept from the ARTCC per hour. The AAR is used to calculate the desired interval between successive arrival aircraft.
Airport Departure Rate (ADR)
A dynamic parameter specifying the number of aircraft which can depart an airport and the airspace can accept per hour.
Airport Diagram
A full-page depiction of the airport that includes the same features of the airport sketch plus additional details such as taxiway identifiers, airport latitude and longitude, and building identification. Airport diagrams are located in the U.S. Terminal Procedures booklet following the instrument approach charts for a particular airport.
Airport Elevation
The highest point of an airport’s usable runways measured in feet from mean sea level.
Airport Lighting
Various lighting aids that may be installed on an airport.
Airport Marking Aids
Markings used on runway and taxiway surfaces to identify a specific runway, a runway threshold, a centerline, a hold line, etc. A runway should be marked in accordance with its present usage such as: a. Visual. b. Nonprecision instrument. c. Precision instrument.
Airport Reference Point (ARP)
The approximate geometric center of all usable runway surfaces.
Airport Reservation Office
Office responsible for monitoring the operation of slot controlled airports. It receives and processes requests for unscheduled operations at slot controlled airports.
Airport Rotating Beacon
A visual NAVAID operated at many airports. At civil airports, alternating white and green flashes indicate the location of the airport. At military airports, the beacons flash alternately white and green, but are differentiated from civil beacons by dualpeaked (two quick) white flashes between the green flashes.
Airport Sketch
Depicts the runways and their length, width, and slope, the touchdown zone elevation, the lighting system installed on the end of the runway, and taxiways. Airport sketches are located on the lower left or right portion of the instrument approach chart.
Airport Stream Filter (ASF)
An on/off filter that allows the conflict notification function to be inhibited for arrival streams into single or multiple airports to prevent nuisance alerts.
Airport surface detection equipment (ASDE)
Radar equipment specifically designed to detect all principal features and traffic on the surface of an airport, presenting the entire image on the control tower console; used to augment visual observation by tower personnel of aircraft and/or vehicular movements on runways and taxiways.
Airport Surveillance Radar
Approach control radar used to detect and display an aircraft’s position in the terminal area. ASR provides range and azimuth information but does not provide elevation data. Coverage of the ASR can extend up to 60 miles.
Airport surveillance radar (ASR)
Approach control radar used to detect and display an aircrafts position in the terminal area.
Airport surveillance radar approach
An instrument approach in which ATC issues instructions for pilot compliance based on aircraft position in relation to the final approach course and the distance from the end of the runway as displayed on the controllers radar scope.
Airport Taxi Charts
Aeronautical Chart.
Airport Traffic Control Service
A service provided by a control tower for aircraft operating on the movement area and in the vicinity of an airport.
Airport Traffic Control Tower
Tower.
Airport/Facility Directory
A publication designed primarily as a pilot’s operational manual containing all airports, seaplane bases, and heliports open to the public including communications data, navigational facilities, and certain special notices and procedures. This publication is issued in seven volumes according to geographical area. (Renamed to Chart Supplement)
Airport/Facility Directory (A/FD)
Regional booklets published by the National Aeronautical Charting Office. Title changed to Chart Supplement. (NACO) that provide textual information about all airports, both VFR and IFR. The A/FD includes runway length and width, runway surface, load bearing capacity, runway slope, airport services, and hazards such as birds and reduced visibility.
Airship
An engine-driven lighter-than-air aircraft that can be steered.
Airspace Conflict
Predicted conflict of an aircraft and active Special Activity Airspace (SAA).
Airspace Flow Program (AFP)
AFP is a Traffic Management (TM) process administered by the Air Traffic Control System Command Center (ATCSCC) where aircraft are assigned an Expect Departure Clearance Time (EDCT) in order to manage capacity and demand for a specific area of the National Airspace System (NAS). The purpose of the program is to mitigate the effects of en route constraints. It is a flexible program and may be implemented in various forms depending upon the needs of the air traffic system.
Airspace Hierarchy
Within the airspace classes, there is a hierarchy and, in the event of an overlap of airspace: Class A preempts Class B, Class B preempts Class C, Class C preempts Class D, Class D preempts Class E, and Class E preempts Class G.
Airspeed
Rate of the aircraft’s progress through the air.
Airspeed indicator
A differential pressure gauge that measures the dynamic pressure of the air through which the aircraft is flying. Displays the crafts airspeed, typically in knots, to the pilot.
Airstart
The starting of an aircraft engine while the aircraft is airborne, preceded by engine shutdown during training flights or by actual engine failure.
Airway
An airway is based on a centerline that extends from one navigation aid or intersection to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.
Airway Beacon
Used to mark airway segments in remote mountain areas. The light flashes Morse Code to identify the beacon site.
Airway [ICAO]
A control area or portion thereof established in the form of corridor equipped with radio navigational aids.
Airworthiness
A condition in which the aircraft conforms to its type certificated design including supplemental type certificates, and field approved alterations. The aircraft must also be in a condition for safe flight as determined by annual, 100 hour, preflight and any other required inspections.
Airworthiness Certificate
A certificate issued by the FAA to all aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations.
Airworthiness Directive
A regulatory notice sent out by the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from continuing to meet its conditions for airworthiness. Airworthiness Directives (AD notes) must be complied with within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance must be recorded in the aircraft’s maintenance records.
Albedo
The ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it, commonly expressed in percentage; in meteorology, usually used in reference to insolation (solar radiation); i.e., the albedo of wet sand is 9, meaning that about 9% of the incident insolation is reflected; albedoes of other surfaces range upward to 80-85 for fresh snow cover; average albedo for the earth and its atmosphere has been calculated to range from 35 to 43.
Alerfa (Alert Phase) [ICAO]
A situation wherein apprehension exists as to the safety of an aircraft and its occupants.
Alert
A notification to a position that there is an aircraft-to-aircraft or aircraft-to-airspace conflict, as detected by Automated Problem Detection (APD).
Alert area
An area in which there is a high volume of pilot training or an unusual type of aeronautical activity.
Alert Notice
A request originated by a flight service station (FSS) or an air route traffic control center (ARTCC) for an extensive communication search for overdue, unreported, or missing aircraft.
Alerting Service
A service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid and assist such organizations as required.
Almanac data
Information the global positioning system (GPS) receiver can obtain from one satellite which describes the approximate orbital positioning of all satellites in the constellation. This information is necessary for the GPS receiver to know what satellites to look for in the sky at a given time.
Along-Track Distance (ATD)
The distance measured from a point-in-space by systems using area navigation reference capabilities that are not subject to slant range errors.
Alpha Mode Of Operation
The operation of a turboprop engine that includes all of the flight operations, from takeoff to landing. Alpha operation is typically between 95 percent to 100 percent of the engine operating speed.
Alphanumeric Display
Letters and numerals used to show identification, altitude, beacon code, and other information concerning a target on a radar display.
Alternate Aerodrome [ICAO]
An aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to or to land at the aerodrome of intended landing. Note: The aerodrome from which a flight departs may also be an en-route or a destination alternate aerodrome for the flight.
Alternate Air
A device which opens, either automatically or manually, to allow induction airflow to continue should the primary induction air opening become blocked.
Alternate airport
An airport designated in an IFR flight plan, providing a suitable destination if a landing at the intended airport becomes inadvisable.
Alternate Static Source
A manual port that when opened allows the pitot static instruments to sense static pressure from an alternate location should the primary static port become blocked.
Alternate static source valve
A valve in the instrument static air system that supplies reference air pressure to the altimeter, airspeed indicator, and vertical speed indicator if the normal static pickup should become clogged or iced over.
Alternator/Generator
A device that uses engine power to generate electrical power.
Altimeter
A flight instrument that indicates altitude by sensing pressure changes.
Altimeter setting
Station pressure (the barometric pressure at the location the reading is taken) which has been corrected for the height of the station above sea level.
Altimeter setting indicator
A precision aneroid barometer calibrated to indicate directly the altimeter setting.
Altitude
Height expressed in units of distance above a reference plane, usually above mean sea level or above ground.
Altitude (AGL)
The actual height above ground level (AGL) at which the aircraft is flying.
Altitude (MSL)
The actual height above mean sea level (MSL) at which the aircraft is flying.
Altitude Chamber
A device that simulates high altitude conditions by reducing the interior pressure. The occupants will suffer from the same physiological conditions as flight at high altitude in an unpressurized aircraft.
Altitude Engine
A reciprocating aircraft engine having a rated takeoff power that is producible from sea level to an established higher altitude.
Altitude Readout
An aircraft’s altitude, transmitted via the Mode C transponder feature, that is visually displayed in 100-foot increments on a radar scope having readout capability.
Altitude Reservation
Airspace utilization under prescribed conditions normally employed for the mass movement of aircraft or other special user requirements which cannot otherwise be accomplished. ALTRVs are approved by the appropriate FAA facility.
Altitude Restriction
An altitude or altitudes, stated in the order flown, which are to be maintained until reaching a specific point or time. Altitude restrictions may be issued by ATC due to traffic, terrain, or other airspace considerations.
Altitude Restrictions Are Canceled
Adherence to previously imposed altitude restrictions is no longer required during a climb or descent.
Altitude [ICAO]
The vertical distance of a level, a point or an object considered as a point, measured from mean sea level (MSL).
Altocumulus
White or gray layers or patches of cloud, often with a waved appearance; cloud elements appear as rounded masses or rolls; composed mostly of liquid water droplets which may be supercooled; may contain ice crystals at subfreezing temperatures.
Altocumulus castellanus
A species of middle cloud of which at least a fraction of its upper part presents some vertically developed, cumuliform protuberances (some of which are taller than they are wide, as castles) and which give the cloud a crenelated or turreted appearance; especially evident when seen from the side; elements usually have a common base arranged in lines. This cloud indicates instability and turbulence at the altitudes of occurrence.
Amateur rocket
An unmanned rocket that:
(1) Is propelled by a motor or motors having a combined total impulse of 889,600 Newton-seconds (200,000 pound-seconds) or less; and
(2) Cannot reach an altitude greater than 150 kilometers (93.2 statute miles) above the earth’s surface.
Ambient pressure
The pressure in the area immediately surrounding the aircraft.
Ambient temperature
The temperature in the area immediately surrounding the aircraft.
Amendment status
The circulation date and revision number of an instrument approach procedure, printed above the procedure identification.
Ammeter
An instrument installed in series with an electrical load used to measure the amount of current flowing through the load.
Anemometer
An instrument for measuring wind speed.
Aneroid
The sensitive component in an altimeter or barometer that measures the absolute pressure of the air. It is a sealed, flat capsule made of thin disks of corrugated metal soldered together and evacuated by pumping all of the air out of it.
Aneroid barometer
An instrument that measures the absolute pressure of the atmosphere by balancing the weight of the air above it against the spring action of the aneroid.
Angel
In radar meteorology, an echo caused by physical phenomena not discernible to the eye; they have been observed when abnormally strong temperature and/or moisture gradients were known to exist; sometimes attributed to insects or birds flying in the radar beam.
Angle Of Attack
The acute angle between the chord line of the airfoil and the direction of the relative wind.
Angle Of Incidence
The angle formed by the chord line of the wing and a line parallel to the longitudinal axis of the airplane.
Anhedral
A downward slant from root to tip of an aircraft’s wing or horizontal tail surface.
Annual Inspection
A complete inspection of an aircraft and engine, required by the Code of Federal Regulations, to be accomplished every 12 calendar months on all certificated aircraft. Only an A&P technician holding an Inspection Authorization can conduct an annual inspection.
Anomalous propagation (sometimes called A P )
In radar meteorology, the greater than normal bending of the radar beam such that echoes are received from ground targets at distances greater than normal ground clutter.
Anti-ice
Preventing the accumulation of ice on an aircraft structure via a system designed for that purpose.
Anti-Icing
The prevention of the formation of ice on a surface. Ice may be prevented by using heat or by covering the surface with a chemical that prevents water from reaching the surface. Anti-icing should not be confused with deicing, which is the removal of ice after it has formed on the surface.
Anticyclone
An area of high atmospheric pressure which has a closed circulation that is anticyclonic, i.e., as viewed from above, the circulation is clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere, undefined at the Equator.
Antiservo tab
An adjustable tab attached to the trailing edge of a stabilator that moves in the same direction as the primary control. It is used to make the stabilator less sensitive.
Anvil cloud
Popular name given to the top portion of a cumulonimbus cloud having an anvil-like form.
Anxiety
Mental discomfort that arises from the fear of anything, real or imagined. May have a potent effect on actions and the ability to learn from perceptions.
APOB
A sounding made by an aircraft.
Appliance
Any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.
Application
A basic level of learning at which the student puts something to use that has been learned and understood.
Application step
The third step of the teaching process, where the student performs the procedure or demonstrates the knowledge required in the lesson. In the telling-and-doing technique of flight instruction, this step consists of the student doing the procedure while explaining it.
Approach Clearance
Authorization by ATC for a pilot to conduct an instrument approach. The type of instrument approach for which a clearance and other pertinent information is provided in the approach clearance when required.
Approach Control Facility
A terminal ATC facility that provides approach control service in a terminal area.
Approach Control Service
Air traffic control service provided by an approach control facility for arriving and departing VFR/IFR aircraft and, on occasion, en route aircraft. At some airports not served by an approach control facility, the ARTCC provides limited approach control service.
Approach Control Service [ICAO]
Air traffic control service for arriving or departing controlled flights.
Approach End of Runway (AER)
The first portion of the runway available for landing. If the runway threshold is displaced, use the displaced threshold latitude/longitude as the AER.
Approach Fix
From a database coding standpoint, an approach fix is considered to be an identifiable point in space from the intermediate fix (IF) inbound. A fix located between the initial approach fix (IAF) and the IF is considered to be associated with the approach transition or feeder route.
Approach Gate
An imaginary point used by ATC to vector aircraft to the final approach course. The approach gate is established along the final approach course 1 NM from the final approach fix (FAF) on the side away from the airport and is located no closer than 5 NM from the landing threshold.
Approach Light System (ALS)
An airport lighting facility which provides visual guidance to landing aircraft by radiating light beams in a directional pattern by which the pilot aligns the aircraft with the extended centerline of the runway on his/her final approach for landing. Condenser-Discharge Sequential Flashing Lights/Sequenced Flashing Lights may be installed in conjunction with the ALS at some airports. Types of Approach Light Systems are: ALSF-1, ALSF-2, SSALF, SSALR, MALSF, MALSR, LDIN, RAIL, ODALS.
Approach lighting system (ALS)
Provides lights that will penetrate the atmosphere far enough from touchdown to give directional, distance, and glide path information for safe transition from instrument to visual flight.
Approach Sequence
The order in which aircraft are positioned while on approach or awaiting approach clearance.
Approach Sequence [ICAO]
The order in which two or more aircraft are cleared to approach to land at the aerodrome.
Approach Speed
The recommended speed contained in aircraft manuals used by pilots when making an approach to landing. This speed will vary for different segments of an approach as well as for aircraft weight and configuration.
Appropriate ATS Authority [ICAO]
The relevant authority designated by the State responsible for providing air traffic services in the airspace concerned. In the United States, the “appropriate ATS authority” is the Program Director for Air Traffic Planning and Procedures, ATP-1.
Appropriate Authority
A. Regarding flight over the high seas: the relevant authority is the State of Registry.
B. Regarding flight over other than the high seas: the relevant authority is the State having sovereignty over the territory being overflown.
Appropriate Obstacle Clearance Minimum Altitude
Any of the following: Minimum En Route IFR Altitude, Minimum IFR Altitude, Minimum Obstruction Clearance Altitude, Minimum Vectoring Altitude.
Appropriate Terrain Clearance Minimum Altitude
Any of the following: Minimum En Route IFR Altitude, Minimum IFR Altitude, Minimum Obstruction Clearance Altitude, Minimum Vectoring Altitude.
Approved
Unless used with reference to another person, approved by the FAA or any person to whom the FAA has delegated its authority in the matter concerned, or approved under the provisions of a bilateral agreement between the United States and a foreign country or jurisdiction.
Approved Type Certificate
A certificate of approval issued by the FAA for the design of an aircraft, engine, or propeller.
Apron
A defined area on an airport or heliport intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, refueling, parking, or maintenance. With regard to seaplanes, a ramp is used for access to the apron from the water.
Apron [ICAO]
A defined area, on a land aerodrome, intended to accommodate aircraft for purposes of loading or unloading passengers, mail or cargo, refueling, parking or maintenance.
Arc
The track over the ground of an aircraft flying at a constant distance from a navigational aid by reference to distance measuring equipment (DME).
Arctic air
An air mass with characteristics developed mostly in winter over Arctic surfaces of ice and snow. Arctic air extends to great heights, and the surface temperatures are basically, but not always, lower than those of polar air.
Arctic front
The surface of discontinuity between very cold (Arctic) air flowing directly from the Arctic region and another less cold and, consequently, less dense air mass.
Area chart
Part of the low-altitude en route chart series, this chart furnishes terminal data at a larger scale for congested areas.
Area Control Center [ICAO]
An air traffic control facility primarily responsible for ATC services being provided IFR aircraft during the en route phase of flight. The U.S. equivalent facility is an air route traffic control center (ARTCC).
Area forecast (FA)
A report that gives a picture of clouds, general weather conditions, and visual meteorological conditions (VMC) expected over a large area encompassing several states. (Discontinued, replaced by Graphical Forecasts for Aviation)
Area Navigation (RNAV)
A method of navigation that permits aircraft operations on any desired course within the coverage of station referenced navigation signals or within the limits of self contained system capability.
Area Navigation (RNAV) Approach Configuration
Includes Standard T, Modified T, Standard I, Terminal Arrival Area (TAA).
Area navigation (RNAV) route
An ATS route based on RNAV that can be used by suitably equipped aircraft.
Area of operation
A phase of the practical test within the PTS.
Arm
(GAMA) The horizontal distance from the reference datum to the center of gravity (CG) of an item. The algebraic sign is plus (+) if measured aft of the datum or to the right side of the center line when considering a lateral calculation. The algebraic sign is minus (-) if measured forward of the datum or the left side of the center line when considering a lateral calculation.
Armed Forces
The Army, Navy, Air Force, Marine Corps, and Coast Guard, including their regular and reserve components and members serving without component status.
Army Aviation Flight Information Bulletin
A bulletin that provides air operation data covering Army, National Guard, and Army Reserve aviation activities.
Arresting System
A safety device consisting of two major components, namely, engaging or catching devices and energy absorption devices for the purpose of arresting both tailhook and/or nontailhook-equipped aircraft. It is used to prevent aircraft from overrunning runways when the aircraft cannot be stopped after landing or during aborted takeoff. Arresting systems have various names; e.g., arresting gear, hook device, wire barrier cable.
Arrival Aircraft Interval
An internally generated program in hundredths of minutes based upon the AAR. AAI is the desired optimum interval between successive arrival aircraft over the vertex.
Arrival Center
The ARTCC having jurisdiction for the impacted airport.
Arrival Delay
A parameter which specifies a period of time in which no aircraft will be metered for arrival at the specified airport.
Arrival Sector
An operational control sector containing one or more meter fixes.
Arrival Sector Advisory List
An ordered list of data on arrivals displayed at the PVD/MDM of the sector which controls the meter fix.
Arrival Sequencing Program
The automated program designed to assist in sequencing aircraft destined for the same airport.
Arrival Time
The time an aircraft touches down on arrival.
Aspect ratio
Span of a wing divided by its average chord.
Associated
A radar target displaying a data block with flight identification and altitude information.
Astronomical twilight
The period of time before sunrise and after sunset when the sun is not more than 18° below the horizon.
Asymmetric thrust
Also known as P-factor. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind.The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.
ATC Advises
Used to prefix a message of noncontrol information when it is relayed to an aircraft by other than an air traffic controller.
ATC Assigned Airspace
Airspace of defined vertical/lateral limits, assigned by ATC, for the purpose of providing air traffic segregation between the specified activities being conducted within the assigned airspace and other IFR air traffic.
ATC Clearance
Air Traffic Clearance.
ATC Clears
Used to prefix an ATC clearance when it is relayed to an aircraft by other than an air traffic controller.
ATC Instructions
Directives issued by air traffic control for the purpose of requiring a pilot to take specific actions; e.g., “Turn left heading two five zero,” “Go around,” “Clear the runway.”
ATC Preferred Route Notification
URET notification to the appropriate controller of the need to determine if an ATC preferred route needs to be applied, based on destination airport.
ATC Preferred Routes
Preferred routes that are not automatically applied by Host.
ATC Requests
Used to prefix an ATC request when it is relayed to an aircraft by other than an air traffic controller.
ATC Security Services
Communications and security tracking provided by an ATC facility in support of the DHS, the DOD, or other Federal security elements in the interest of national security. Such security services are only applicable within designated areas. ATC security services do not include ATC basic radar services or flight following.
ATC Security Services Position
The position responsible for providing ATC security services as defined. This position does not provide ATC, IFR separation, or VFR flight following services, but is responsible for providing security services in an area comprising airspace assigned to one or more ATC operating sectors. This position may be combined with control positions.
ATC Security Tracking
The continuous tracking of aircraft movement by an ATC facility in support of the DHS, the DOD, or other security elements for national security using radar (i.e., radar tracking) or other means (e.g., manual tracking) without providing basic radar services (including traffic advisories) or other ATC services not defined in this section.
Atmosphere
The mass of air surrounding the Earth.
Atmospheric pressure (also called barometric pressure)
The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the “column” of air lying directly above the point in question.
Atmospheric propagation delay
A bending of the electromagnetic (EM) wave from the satellite that creates an error in the GPS system.
Atmospherics
Disturbing effects produced in radio receiving apparatus by atmospheric electrical phenomena such as an electrical storm. Static.
ATS Route [ICAO]
A specified route designed for channelling the flow of traffic as necessary for the provision of air traffic services. Note: The term “ATS Route” is used to mean variously, airway, advisory route, controlled or uncontrolled route, arrival or departure, etc.
Attenuation
In radar meteorology, any process which reduces power density in radar signals.
Attitude
The position of an aircraft as determined by the relationship of its axes and a reference, usually the earth’s horizon.
Attitude and heading reference system (AHRS)
A system composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.
Attitude and heading reference systems (AHRS)
System composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.
Attitude director indicator (ADI)
An aircraft attitude indicator that incorporates flight command bars to provide pitch and roll commands.
Attitude Indicator
An instrument which uses an artificial horizon and miniature airplane to depict the position of the airplane in relation to the true horizon. The attitude indicator senses roll pitch, which is the up and down as well as movement of the airplane’s nose.
Attitude instrument flying
Controlling the aircraft by reference to the instruments rather than by outside visual cues.
Attitude management
The ability to recognize one’s own hazardous attitudes and the willingness to modify them as
Aurora
A luminous, radiant emission over middle and high latitudes confined to the thin air of high altitudes and centered over the earth’s magnetic poles. Called “aurora borealis” (northern lights) or “aurora australis” according to its occurrence in the Northern or Southern Hemisphere, respectively.
Authentic assessment
An assessment in which the student is asked to perform real-world tasks, and demonstrate a meaningful application of skills and competencies.
Autokinesis
This is caused by staring at a single point of light against a dark background for more than a few seconds. After a few moments, the light appears to move on its own.
Autoland Approach
An autoland approach is a precision instrument approach to touchdown and, in some cases, through the landing rollout. An autoland approach is performed by the aircraft autopilot which is receiving position information and/or steering commands from onboard navigation equipment. Note: Autoland and coupled approaches are flown in VFR and IFR. It is common for carriers to require their crews to fly coupled approaches and autoland approaches (if certified) when the weather conditions are less than approximately 4,000 RVR.
Automated Information Transfer
A precoordinated process, specifically defined in facility directives, during which a transfer of altitude control and/or radar identification is accomplished without verbal coordination between controllers using information communicated in a full data block.
Automated Mutual-Assistance Vessel Rescue System
A facility which can deliver, in a matter of minutes, a surface picture (SURPIC) of vessels in the area of a potential or actual search and rescue incident, including their predicted positions and their characteristics.
Automated Problem Detection (APD)
An Automation Processing capability that compares trajectories in order to predict conflicts.
Automated Problem Detection Boundary (ABP)
The adapted distance beyond a facilities boundary defining the airspace within which URET performs conflict detection.
Automated Problem Detection Inhibited Area (APDIA)
Airspace surrounding a terminal area within which APD is inhibited for all flights within that airspace.
Automated Radar Terminal Systems (ARTS)
A generic term for several tracking systems included in the Terminal Automation Systems (TAS). ARTS plus a suffix roman numeral denotes a major modification to that system.
Automated Surface Observing Station (ASOS)
Weather reporting system which provides surface observations every minute via digitized voice broadcasts and printed reports.
Automated Surface Observing System (ASOS)
A weather observing system that provides minute-by-minute weather observations such as temperature, dew point, wind, altimeter setting, visibility, sky condition, and precipitation. Some ASOS stations include a precipitation discriminator which can differentiate between liquid and frozen precipitation.
Automated Surface Observing System (ASOS)/Automated Weather Sens
The ASOS/AWSS is the primary surface weather observing system of the U.S.
Automated Unicom
Provides completely automated weather, radio check capability and airport advisory information on an Automated UNICOM system. These systems offer a variety of features, typically selectable by microphone clicks, on the UNICOM frequency. Availability will be published in the Airport/Facility Directory and approach charts.
Automated Weather Observation System (AWOS)
A suite of weather sensors that are procured by the FAA or purchased by individuals, groups, airports, etc. It is important to note that the absence of reported precipitation does not mean that such conditions do not exist. The AWOS may not be configured to report this information or have precipitation reporting capability. A detailed description of AWOS’s capabilities can be found in the AIM.
Automated Weather Observing System (AWOS)
A suite of sensors which measure, collect, and disseminate weather data. AWOS stations provide a minute-by minute update of weather parameters such as wind speed and direction, temperature and dew point, visibility, cloud heights and types, precipitation, and barometric pressure. A variety of AWOS system types are available (from AWOS 1 to AWOS 3), each of which includes a different sensor array.
Automated Weather Observing System (AWOS).
Automated weather reporting system consisting of various sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast weather data.
Automated Weather Sensor System (AWSS)
The AWSS is part of the Aviation Surface Weather Observation Network suite of programs and provides pilots and other users with weather information through the Automated Surface Observing System. The AWSS sensor suite automatically collects, measures, processes, and broadcasts surface weather data.
Automated Weather System
Any of the automated weather sensor platforms that collect weather data at airports and disseminate the weather information via radio and/or landline. The systems currently consist of the Automated Surface Observing System (ASOS), Automated Weather Sensor System (AWSS) and Automated Weather Observation System (AWOS).
Automatic Altitude Report
Altitude Readout.
Automatic Altitude Reporting
That function of a transponder which responds to Mode C interrogations by transmitting the aircraft’s altitude in 100-foot increments.
Automatic Carrier Landing System
U.S. Navy final approach equipment consisting of precision tracking radar coupled to a computer data link to provide continuous information to the aircraft, monitoring capability to the pilot, and a backup approach system.
Automatic Dependent Surveillance (ADS) [ICAO]
A surveillance technique in which aircraft automatically provide, via a data link, data derived from on-board navigation and position fixing systems, including aircraft identification, four dimensional position and additional data as appropriate.
Automatic dependent surveillance broadcast (ADS-B)
A device used in aircraft that repeatedly broadcasts a message that includes position (such as latitude, longitude, and altitude), velocity, and possibly other information.
Automatic Dependent Surveillance-Broadcast (ADS-B)
A surveillance system that continuously broadcasts GPS position information, aircraft identification, altitude, velocity vector, and direction to all other aircraft and air traffic control facilities within a specific area. Automatic dependent surveillance-broadcast (ADS-B) information will be displayed in the cockpit via a cockpit display of traffic information (CDTI) unit, providing the pilot with greater situational awareness. ADS-B transmissions will also provide controllers with a more complete picture of traffic and will update that information more frequently than other surveillance equipment.
Automatic Dependent Surveillance-Contract (ADS-C)
A data link position reporting system, controlled by a ground station, that establishes contracts with an aircraft’s avionics that occur automatically whenever specific events occur, or specific time intervals are reached.
Automatic dependent surveillance—broadcast (ADS-B)
A device used in aircraft that repeatedly broadcasts a message that includes position (such as latitude, longitude, and altitude), velocity, and possibly other information.
Automatic Direction Finder
An aircraft radio navigation system which senses and indicates the direction to a L/MF nondirectional radio beacon (NDB) ground transmitter. Direction is indicated to the pilot as a magnetic bearing or as a relative bearing to the longitudinal axis of the aircraft depending on the type of indicator installed in the aircraft. In certain applications, such as military, ADF operations may be based on airborne and ground transmitters in the VHF/UHF frequency spectrum.
Automatic direction finder (ADF)
Electronic navigation equipment that operates in the low- and medium-frequency bands. Used in conjunction with the ground-based nondirectional beacon (NDB), the instrument displays the number of degrees clockwise from the nose of the aircraft to the station being received.
Automatic Flight Information Service (AFIS)
Alaska FSSs Only The continuous broadcast of recorded non-control information at airports in Alaska where a FSS provides local airport advisory service. The AFIS broadcast automates the repetitive transmission of essential but routine information such as weather, wind, altimeter, favored runway, breaking action, airport NOTAMs, and other applicable information. The information is continuously broadcast over a discrete VHF radio frequency (usually the ASOS/AWSS/AWOS frequency.
Automatic Terminal Information Service
The continuous broadcast of recorded noncontrol information in selected terminal areas. Its purpose is to improve controller effectiveness and to relieve frequency congestion by automating the repetitive transmission of essential but routine information; e.g., “Los Angeles information Alfa. One three zero zero Coordinated Universal Time. Weather, measured ceiling two thousand overcast, visibility three, haze, smoke, temperature seven one, dew point five seven, wind two five zero at five, altimeter two niner niner six. I-L-S Runway Two Five Left approach in use, Runway Two Five Right closed, advise you have Alfa.”
Automatic Terminal Information Service (ATIS)
A recorded broadcast available at most airports with an operating control tower that includes crucial information about runways and instrument approaches in use, specific outages, and current weather conditions, including visibility.
Automatic Terminal Information Service [ICAO]
The provision of current, routine information to arriving and departing aircraft by means of continuous and repetitive broadcasts throughout the day or a specified portion of the day.
Autopilot
An automatic flight control system which keeps an aircraft in level flight or on a set course. Automatic pilots can be directed by the pilot, or they may be coupled to a radio navigation signal.
Autorotation
A rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion.
Autorotative Landing/Touchdown Autorotation
Used by a pilot to indicate that the landing will be made without applying power to the rotor.
Auxiliary rotor
A rotor that serves either to counteract the effect of the main rotor torque on a rotorcraft or to maneuver the rotorcraft about one or more of its three principal axes.
Available Landing Distance (ALD)
The portion of a runway available for landing and roll-out for aircraft cleared for LAHSO. This distance is measured from the landing threshold to the hold-short point.
Aviation medical examiner (AME)
A physician with training in aviation medicine designated by the Civil Aerospace Medical Institute (CAMI).
Aviation Routine Weather Report (METAR)
Observation of current surface weather reported in a standard international format.
Aviation Weather Service
A service provided by the National Weather Service (NWS) and FAA which collects and disseminates pertinent weather information for pilots, aircraft operators, and ATC. Available aviation weather reports and forecasts are displayed at each NWS office and FAA FSS.
Aviation Weather Service Program
Aviation weather service provided by the NWS and the FAA that collects and disseminates pertinent weather information for pilots, aircraft operators, and air traffic control (ATC).
Axes Of An Aircraft
Three imaginary lines that pass through an aircraft’s center of gravity. The axes can be considered as imaginary axles around which the aircraft turns. The three axes pass through the center of gravity at 90°angles to each other. The axis from nose to tail is the longitudinal axis, the axis that passes from wingtip to wingtip is the lateral axis, and the axis that passes vertically through the center of gravity is the vertical axis.
Axial Flow Compressor
A type of compressor used in a turbine engine in which the airflow through the compressor is essentially linear. An axial-flow compressor is made up of several stages of alternate rotors and stators. The compressor ratio is determined by the decrease in area of the succeeding stages.
Azimuth (MLS)
A magnetic bearing extending from an MLS navigation facility. Note: Azimuth bearings are described as magnetic and are referred to as “azimuth” in radio telephone communications.
Azimuth card
A card that may be set, gyroscopically controlled, or driven by a remote compass.
Back course (BC)
The reciprocal of the localizer course for an ILS. When flying a back-course approach, an aircraft approaches the instrument runway from the end at which the localizer antennas are installed.
Back Side Of The Power Curve
Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.
Back-Taxi
A term used by air traffic controllers to taxi an aircraft on the runway opposite to the traffic flow. The aircraft may be instructed to back-taxi to the beginning of the runway or at some point before reaching the runway end for the purpose of departure or to exit the runway.
Backing
Shifting of the wind in a counterclockwise direction with respect to either space or time; opposite of veering. Commonly used by meteorologists to refer to a cyclonic shift (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere).
Backscatter
Pertaining to radar, the energy reflected or scattered by a target; an echo.
Balance tab
An auxiliary control mounted on a primary control surface, which automatically moves in the direction opposite the primary control to provide an aerodynamic assist in the movement of the control. Sometimes referred to as a servo tab.
Balanced Laterally
Balanced in such a way that the wings tend to remain level.
Balked Landing
A go-around.
Ballast
Removable or permanently installed weight in an aircraft used to bring the center of gravity into the allowable range.
Balloon
The result of a too aggressive flare during landing causing the aircraft to climb.
Banner cloud (also called cloud banner)
A banner-like cloud streaming off from a mountain peak.
Baro-aiding
A method of augmenting the GPS integrity solution by using a non-satellite input source. To ensure that baro-aiding is available, the current altimeter setting must be entered as described in the operating manual.
Barograph
A continuous-recording barometer.
Barometer
An instrument for measuring the pressure of the atmosphere; the two principle types are mercurial and aneroid.
Barometric altimeter
Also called a pressure altimeter. An aneroid barometer with a scale graduated in altitude instead of pressure using standard atmospheric pressure-height relationships; shows indicated altitude (not necessarily true altitude); may be set to measure altitude (indicated) from any arbitrarily chosen level.
Barometric pressure
Same as atmospheric pressure—the pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the “column” of air lying directly above the point in question.
Barometric scale
A scale on the dial of an altimeter to which the pilot sets the barometric pressure level from which the altitude shown by the pointers is measured.
Barometric tendency
The change of barometric pressure within a specified period of time. In aviation weather observation, routinely determined periodically, usually for a 3-hour period.
Base Leg
A flight path at right angles to the landing runway off its approach end. The base leg normally extends from the downwind leg to the intersection of the extended runway centerline.
Basic Empty Weight
(GAMA) Standard empty weight plus optional equipment.
Basic Empty Weight (GAMA)
Basic empty weight includes the standard empty weight plus optional and special equipment that has been installed.
Basic need
A perception factor that describes a person’s ability to maintain and enhance the organized self.
Basic Operating Index
The moment of the airplane at its basic operating weight divided by the appropriate reduction factor.
Basic Operating Weight (BOW)
The empty weight of the aircraft plus the weight of the required crew, their baggage and other standard item such as meals and potable water.
Basic Radar Service
These services are provided for VFR aircraft by all commissioned terminal radar facilities. Basic radar service includes safety alerts, traffic advisories, limited radar vectoring when requested by the pilot, and sequencing at locations where procedures have been established for this purpose and/or when covered by a letter of agreement. The purpose of this service is to adjust the flow of arriving IFR and VFR aircraft into the traffic pattern in a safe and orderly manner and to provide traffic advisories to departing VFR aircraft.
Beacon
Aeronautical Beacon.
Beam resolution
The ability of radar to distinguish between targets at approximately the same range but at different azimuths.
Bearing
The horizontal direction to or from any point, usually measured clockwise from true north, magnetic north, or some other reference point through 360 degrees.
Beaufort scale
A scale of wind speeds.
Behaviorism
Theory of learning that stresses the importance of having a particular form of behavior reinforced by someone other than the student to shape or control what is learned.
Below Minimums
Weather conditions below the minimums prescribed by regulation for the particular action involved; e.g., landing minimums, takeoff minimums.
Bernoulli’s Principle
A principle that explains how the pressure of a moving fluid varies with its speed of motion. An increase in the speed of movement causes a decrease in the fluid’s pressure.
Best Angle Of Climb (Vx)
The speed at which the aircraft will produce the most gain in altitude in a given distance.
Best Glide
The airspeed in which the aircraft glides the furthest for the least altitude lost when in non-powered flight.
Best Rate Of Climb (Vy)
The speed at which the aircraft will produce the most gain in altitude in the least amount of time.
Bilge Area
The lowest part of an aircraft structure in which water and contaminants collect.
Biplanes
Airplanes with two sets of wings.
Black blizzard
Same as dust storm—an unusual, frequently severe weather condition characterized by strong winds and dust-filled air over an extensive area.
Blade Face
The flat portion of a propeller blade, resembling the bottom portion of an airfoil.
Blast Fence
A barrier that is used to divert or dissipate jet or propeller blast.
Blast Pad
A surface adjacent to the ends of a runway provided to reduce the erosive effect of jet blast and propeller wash.
Bleed Air
Compressed air tapped from the compressor stages of a turbine engine by use of ducts and tubing. Bleed air can be used for deice, anti-ice, cabin pressurization, heating, and cooling systems.
Bleed Valve
In a turbine engine, a flapper valve, a popoff valve, or a bleed band designed to bleed off a portion of the compressor air to the atmosphere. Used to maintain blade angle of attack and provide stall-free engine acceleration and deceleration.
Blind Speed
The rate of departure or closing of a target relative to the radar antenna at which cancellation of the primary radar target by moving target indicator (MTI) circuits in the radar equipment causes a reduction or complete loss of signal.
Blind Spot
An area from which radio transmissions and/or radar echoes cannot be received. The term is also used to describe portions of the airport not visible from the control tower.
Blind Transmission
A transmission from one station to other stations in circumstances where two-way communication cannot be established, but where it is believed that the called stations may be able to receive the transmission.
Blind Velocity [ICAO]
The radial velocity of a moving target such that the target is not seen on primary radars fitted with certain forms of fixed echo suppression.
Blind Zone
Blind Spot. An area from which radio transmissions and/or radar echoes cannot be received. The term is also used to describe portions of the airport not visible from the control tower.
Blizzard
A severe weather condition characterized by low temperatures and strong winds bearing a great amount of snow, either falling or picked up from the ground.
Block altitude
A block of altitudes assigned by ATC to allow altitude deviations; for example, Maintain block altitude 9 to 11 thousand.
Blocked
Phraseology used to indicate that a radio transmission has been distorted or interrupted due to multiple simultaneous radio transmissions.
Blowing dust
A type of lithometeor composed of dust particles picked up locally from the surface and blown about in clouds or sheets.
Blowing sand
A type of lithometeor composed of sand picked up locally from the surface and blown about in clouds or sheets.
Blowing snow
A type of hydrometeor composed of snow picked up from the surface by the wind and carried to a height of 6 feet or more.
Blowing spray
A type of hydrometeor composed of water particles picked up by the wind from the surface of a large body of water.
Bookmark
A means of saving addresses on the World Wide Web (WWW) for easy future access. Usually done by selecting a button on the web browser screen, it saves the current web address so it does not have to be input again in a lengthy series of characters.
Boost Pump
An electrically driven fuel pump, usually of the centrifugal type, located in one of the fuel tanks. It is used to provide fuel to the engine for starting and providing fuel pressure in the event of failure of the engine driven pump. It also pressurizes the fuel lines to prevent vapor lock.
Boundary Lights
Lights defining the perimeter of an airport or landing area.
Brake horsepower
The power delivered at the propeller shaft (main drive or main output) of an aircraft engine.
Braking Action (Good, Fair, Poor, Or Nil)
A report of conditions on the airport movement area providing a pilot with a degree/quality of braking that he/she might expect. Braking action is reported in terms of good, fair, poor, or nil.
Braking Action Advisories
When tower controllers have received runway braking action reports which include the terms “fair,” “poor,” or “nil,” or whenever weather conditions are conducive to deteriorating or rapidly changing runway braking conditions, the tower will include on the ATIS broadcast the statement, “Braking action advisories are in effect” on the ATIS broadcast. During the time braking action advisories are in effect, ATC will issue the latest braking action report for the runway in use to each arriving and departing aircraft. Pilots should be prepared for deteriorating braking conditions and should request current runway condition information if not volunteered by controllers. Pilots should also be prepared to provide a descriptive runway condition report to controllers after landing.
Branching
A programming technique which allows users of interactive video, multimedia courseware, or online training to choose from several courses of action in moving from one sequence to another.
Breakout
A technique to direct aircraft out of the approach stream. In the context of close parallel operations, a breakout is used to direct threatened aircraft away from a deviating aircraft.
Briefing
An oral presentation where the speaker presents a concise array of facts without inclusion of extensive supporting material.
Bright band
In radar meteorology, a narrow, intense echo on the range-height indicator scope resulting from water-covered ice particles of high reflectivity at the melting level.
Broadcast
Transmission of information for which an acknowledgement is not expected.
Broadcast [ICAO]
A transmission of information relating to air navigation that is not addressed to a specific station or stations.
Buffeting
The beating of an aerodynamic structure or surface by unsteady flow, gusts, etc.; the irregular shaking or oscillation of a vehicle component owing to turbulent air or separated flow.
Building block concept
Concept of learning that new knowledge and skills are best based on a solid foundation of previous experience and/or old learning. As knowledge and skills increase, the base expands, supporting further learning.
Bus Bar
An electrical power distribution point to which several circuits may be connected. It is often a solid metal strip having a number of terminals installed on it.
Bus Tie
A switch that connects two or more bus bars. It is usually used when one generator fails and power is lost to its bus. By closing the switch, the operating generator powers both busses.
Butt (or buttock) Line Zero
A line through the symmetrical center of an aircraft from nose to tail. It serves as the datum for measuring the arms used to determine the lateral CG. Lateral moments that cause the aircraft to rotate clockwise are positive (+) , and those that cause it to rotate counterclockwise are negative (-).
Buys Ballot’s law
If an observer in the Northern Hemisphere stands with his back to the wind, lower pressure is to his left.
Bypass Air
The part of a turbofan’s induction air that bypasses the engine core.
Bypass Ratio
The ratio of the mass airflow in pounds per second through the fan section of a turbofan engine to the mass airflow that passes through the gas generator portion of the engine. Or, the ratio between fan mass airflow (lb/sec.) and core engine mass airflow (lb/sec.).
Cabin altitude
Cabin pressure in terms of equivalent altitude above sea level.
Cabin Pressurization
A condition where pressurized air is forced into the cabin simulating pressure conditions at a much lower altitude and increasing the aircraft occupants comfort.
Cage
The black markings on the ball instrument indicating its neutral position.
Calculated Landing Time
A term that may be used in place of tentative or actual calculated landing time, whichever applies.
Calendar Month
A time period used by the FAA for certification and currency purposes. A calendar month extends from a given day until midnight of the last day of that month.
Calibrated
The instrument indication compared with a standard value to determine the accuracy of the instrument.
Calibrated airspeed
The speed at which the aircraft is moving through the air, found by correcting IAS for instrument and position errors.
Calibrated Airspeed (CAS)
Indicated airspeed corrected for installation error and instrument error. Although manufacturers attempt to keep airspeed errors to a minimum, it is not possible to eliminate all errors throughout the airspeed operating range. At certain airspeeds and with certain flap settings, the installation and instrument errors may total several knots. This error is generally greatest at low airspeeds. In the cruising and higher airspeed ranges, indicated airspeed and calibrated airspeed are approximately the same. Refer to the airspeed calibration chart to correct for possible airspeed errors.
Calibrated orifice
A hole of specific diameter used to delay the pressure change in the case of a vertical speed indicator.
Call For Release
Wherein the overlying ARTCC requires a terminal facility to initiate verbal coordination to secure ARTCC approval for release of a departure into the en route environment.
Call Up
Initial voice contact between a facility and an aircraft, using the identification of the unit being called and the unit initiating the call.
Calm
The absence of wind or of apparent motion of the air.
Camber
The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more pronounced, while the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing.
Cambered
The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more pronounced, while the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing.
CAMs
The manuals containing the certification rules under the Civil Air Regulations.
Canadian Minimum Navigation Performance Specification Airspace
That portion of Canadian domestic airspace within which MNPS separation may be applied.
Canard
The forward wing of a canard configuration and may be a fixed, movable, or variable geometry surface, with or without control surfaces.
Canard configuration
A configuration in which the span of the forward wing is substantially less than that of the main wing.
Cantilever
A wing designed to carry loads without external struts.
Cap cloud
Also called cloud cap. A standing or stationary cap-like cloud crowning a mountain summit.
Carburetor
1. Pressure: A hydromechanical device employing a closed feed system from the fuel pump to the discharge nozzle. It meters fuel through fixed jets according to the mass airflow through the throttle body and discharges it under a positive pressure. Pressure carburetors are distinctly different from float-type carburetors, as they do not incorporate a vented float chamber or suction pickup from a discharge nozzle located in the venturi tube. 2. Float-type: Consists essentially of a main air passage through which the engine draws its supply of air, a mechanism to control the quantity of fuel discharged in relation to the flow of air, and a means of regulating the quantity of fuel/air mixture delivered to the engine cylinders.
Carburetor Ice
Ice that forms inside the carburetor due to the temperature drop caused by the vaporization of the fuel. Induction system icing is an operational hazard because it can cut off the flow of the fuel/air charge or vary the fuel/air ratio.
Cardinal Altitudes
“Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.
Cardinal Flight Levels
Cardinal Altitudes. “Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.
Cascade Reverser
A thrust reverser normally found on turbofan engines in which a blocker door and a series of cascade vanes are used to redirect exhaust gases in a forward direction.
Catch Point
A fix/waypoint that serves as a transition point from the high altitude waypoint navigation structure to an arrival procedure (STAR) or the low altitude ground-based navigation structure.
Category
(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a broad classification of aircraft. Examples include: airplane; rotorcraft; glider; and lighter-than-air; and
(2) As used with respect to the certification of aircraft, means a grouping of aircraft based upon intended use or operating limitations. Examples include: transport, normal, utility, acrobatic, limited, restricted, and provisional.
Category A
With respect to transport category rotorcraft, multiengine rotorcraft designed with engine and system isolation features specified in Part 29 and utilizing scheduled takeoff and landing operations under a critical engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight in the event of engine failure.
Category B
With respect to transport category rotorcraft, single-engine or multiengine rotorcraft which do not fully meet all Category A standards. Category B rotorcraft have no guaranteed stay-up ability in the event of engine failure and unscheduled landing is assumed.
Category C
An Aircraft Approach Category. Speed 121 knots or more but less than 141 knots.
Category D
An Aircraft Approach Category. Speed 141 knots or more but less than 166 knots.
Category E
An Aircraft Approach Category. Speed 166 knots or more.
Category II operations
With respect to the operation of aircraft, a straight-in ILS approach to the runway of an airport under a Category II ILS instrument approach procedure issued by the Administrator or other appropriate authority.
Category III operations
With respect to the operation of aircraft, an ILS approach to, and landing on, the runway of an airport using a Category III ILS instrument approach procedure issued by the Administrator or other appropriate authority.
Category IIIa operations
An ILS approach and landing with no decision height (DH), or a DH below 100 feet (30 meters), and controlling runway visual range not less than 700 feet (200 meters).
Category IIIb operations
An ILS approach and landing with no DH, or with a DH below 50 feet (15 meters), and controlling runway visual range less than 700 feet (200 meters), but not less than 150 feet (50 meters).
Category IIIc operations
An ILS approach and landing with no DH and no runway visual range limitation.
Ceiling
The height above the earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as “broken”, “overcast”, or “obscuration”, and not classified as “thin” or “partial”.
Ceiling balloon
A small balloon used to determine the height of a cloud base or the extent of vertical visibility.
Ceiling light
An instrument which projects a vertical light beam onto the base of a cloud or into surface-based obscuring phenomena; used at night in conjunction with a clinometer to determine the height of the cloud base or as an aid in estimating the vertical visibility.
Ceiling [ICAO]
The height above the ground or water of the base of the lowest layer of cloud below 6,000 meters (20,000 feet) covering more than half the sky.
Ceilometer
A cloud-height measuring system. It projects light on the cloud, detects the reflection by a photo-electric cell, and determines height by triangulation.
Celsius temperature scale (abbreviated C)
A temperature scale with zero degrees as the melting point of pure ice and 100 degrees as the boiling point of pure water at standard sea level atmospheric pressure.
Center
Air Route Traffic Control Center.
Center of Gravity (CG)
(GAMA) The point at which an airplane would balance if suspended. Its distance from the reference datum is determined by dividing the total moment by the total weight of the airplane. It is the mass center of the aircraft, or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated. It may be expressed in percent of MAC (mean aerodynamic cord) or in inches from the reference Center of Lift. The location along the chord line of an airfoil at which all the lift forces produced by the airfoil are considered to be concentrated.
Center of gravity limits
The specified forward and aft points within which the CG must be located during flight. These limits are indicated on pertinent airplane specifications.
Center of gravity range
The distance between the forward and aft CG limits indicated on pertinent airplane specifications.
Center Of Gravity(CG)
The point at which an airplane would balance if it were possible to suspend it at that point. It is the mass center of the airplane, or the theoretical point at which the entire weight of the airplane is assumed to be concentrated. It may be expressed in inches from the reference datum, or in percent of mean aerodynamic chord (MAC). The location depends on the distribution of weight in the airplane.
Center of pressure
A point along the wing chord line where lift is considered to be concentrated. For this reason, the center of pressure is commonly referred to as the center of lift.
Center Radar ARTS Presentation/Processing
A computer program developed to provide a back-up system for airport surveillance radar in the event of a failure or malfunction. The program uses air route traffic control center radar for the processing and presentation of data on the ARTS IIA or IIIA displays.
Center Radar ARTS Presentation/Processing (CENRAP)
CENRAP was developed to provide an alternative to a non-radar environment at terminal facilities should an ASR fail or malfunction. CENRAP sends aircraft radar beacon target information to the ASR terminal facility equipped with ARTS.
Center Radar ARTS Presentation/Processing-Plus
A computer program developed to provide a back-up system for airport surveillance radar in the event of a terminal secondary radar system failure. The program uses a combination of Air Route Traffic Control Center Radar and terminal airport surveillance radar primary targets displayed simultaneously for the processing and presentation of data on the ARTS IIA or IIIA displays.
Center Tracon Automation System (CTAS)
A computerized set of programs designed to aid Air Route Traffic Control Centers and TRACONs in the management and control of air traffic.
Center Weather Advisory
An unscheduled weather advisory issued by Center Weather Service Unit meteorologists for ATC use to alert pilots of existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify or redefine a SIGMET.
Center Weather Advisory (CWA)
An unscheduled weather advisory issued by NWS meteorologists for use by ATC in alerting pilots to existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify a SIGMET.
Center-Of-Gravity Limits
The specified forward and aft points within which the CG must be located during flight. These limits are indicated on pertinent airplane specifications.
Center-Of-Gravity Range
The distance between the forward and aft CG limits indicated on pertinent airplane specifications.
Center’s Area
The specified airspace within which an air route traffic control center (ARTCC) provides air traffic control and advisory service.
Centigrade temperature scale
Same as Celsius temperature scale—a temperature scale with zero degrees as the melting point of pure ice and 100 degrees as the boiling point of pure water at standard sea level atmospheric pressure.
Central East Pacific
An organized route system between the U.S. West Coast and Hawaii.
Centrifugal Flow Compressor
An impeller-shaped device that receives air at its center and slings air outward at high velocity into a diffuser for increased pressure. Also referred to as a radial outflow compressor.
Centrifugal force
An outward force, that opposes centripetal force, resulting from the effect of inertia during a turn.
Centripetal force
A center-seeking force directed inward toward the center of rotation created by the horizontal component of lift in turning flight.
Centroid
The distance in inches aft of the datum of the center of a compartment or a fuel tank for weight and balance purposes.
Certified Tower Radar Display (CTRD)
A FAA radar display certified for use in the NAS.
CG Arm
(GAMA) The arm obtained by adding the airplane’s individual moments and dividing the sum by the total weight.
CG Limits
(GAMA) The extreme center of gravity locations within which the aircraft must be operated at a given weight. These limits are indicated on pertinent FAA aircraft type certificate data sheets, specifications, or weight and balance records.
CG Limits Envelope
An enclosed area on a graph of the airplane loaded weight and the CG location. If lines drawn from the weight and CG cross within this envelope, the airplane is properly loaded.
CG Moment Envelope
An enclosed area on a graph of the airplane loaded weight and loaded moment. If lines drawn from the weight and loaded moment cross within this envelope, the airplane is properly loaded.
Chaff
Pertaining to radar, (1) short, fine strips of metallic foil dropped from aircraft, usually by military forces, specifically for the purpose of jamming radar; (2) applied loosely to echoes resulting from chaff.
Change of state
In meteorology, the transformation of water from one form, i.e., solid (ice), liquid, or gaseous (water vapor), to any other form. There are six possible transformations designated by the five terms following: condensation, evaporation, freezing, melting, or sublimation.
Changeover Point (COP)
A COP indicates the point where a frequency change is necessary between navigation aids when other than the midpoint on an airway, to receive course guidance from the facility ahead of the aircraft instead of the one behind. These COPs divide an airway or route segment and ensure continuous reception of navigational signals at the prescribed minimum en route IFR altitude.
Charted VFR Flyways
Charted VFR Flyways are flight paths recommended for use to bypass areas heavily traversed by large turbine-powered aircraft. Pilot compliance with recommended flyways and associated altitudes is strictly voluntary. VFR Flyway Planning charts are published on the back of existing VFR Terminal Area charts.
Charted Visual Flight Procedure (CVFP)
A CVFP may be established at some towered airports for environmental or noise considerations, as well as when necessary for the safety and efficiency of air traffic operations. Designed primarily for turbojet aircraft, CVFPs depict prominent landmarks, courses, and recommended altitudes to specific runways.
Charted Visual Flight Procedure Approach
An approach conducted while operating on an instrument flight rules (IFR) flight plan which authorizes the pilot of an aircraft to proceed visually and clear of clouds to the airport via visual landmarks and other information depicted on a charted visual flight procedure. This approach must be authorized and under the control of the appropriate air traffic control facility. Weather minimums required are depicted on the chart.
Chase
An aircraft flown in proximity to another aircraft normally to observe its performance during training or testing.
Chase Aircraft
An aircraft flown in proximity to another aircraft normally to observe its performance during training or testing.
Checklist
A tool that is used as a human factors aid in aviation safety. It is a systematic and sequential list of all operations that must be performed to properly accomplish a task.
Chinook
A warm, dry foehn wind blowing down the eastern slopes of the Rocky Mountains over the adjacent plains in the U.S. and Canada.
Chord
A straight-line distance across a wing from leading edge to trailing edge.
Chord Line
An imaginary straight line drawn through an airfoil from the leading edge to the trailing edge.
Circle To Runway (Runway Number)
Used by ATC to inform the pilot that he/she must circle to land because the runway in use is other than the runway aligned with the instrument approach procedure. When the direction of the circling maneuver in relation to the airport/runway is required, the controller will state the direction (eight cardinal compass points) and specify a left or right downwind or base leg as appropriate; e.g., “Cleared VOR Runway Three Six Approach circle to Runway Two Two,” or “Circle northwest of the airport for a right downwind to Runway Two Two.”
Circle-To-Land Maneuver
A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight-in landing from an instrument approach is not possible or is not desirable. At tower controlled airports, this maneuver is made only after ATC authorization has been obtained and the pilot has established required visual reference to the airport.
Circling approach
A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight- in landing from an instrument approach is not possible or is not desirable.
Circling Maneuver
Circle-To-Land Maneuver.
Circling Minima
Landing Minimums [for a circling approach].
Circuit Breaker
A circuit-protecting device that opens the circuit in case of excess current flow. A circuit breakers differs from a fuse in that it can be reset without having to be replaced.
Cirriform
All species and varieties of cirrus, cirrocumulus, and cirrostratus clouds; descriptive of clouds composed mostly or entirely of small ice crystals, usually transparent and white; often producing halo phenomena not observed with other cloud forms. Average height ranges upward from 20,000 feet in middle latitudes.
Cirrocumulus
A cirriform cloud appearing as a thin sheet of small white puffs resembling flakes or patches of cotton without shadows; sometimes confused with altocumulus.
Cirrostratus
A cirriform cloud appearing as a whitish veil, usually fibrous, sometimes smooth; often produces halo phenomena; may totally cover the sky.
Cirrus
A cirriform cloud in the form of thin, white feather-like clouds in patches or narrow bands; have a fibrous and/or silky sheen; large ice crystals often trail downward a considerable vertical distance in fibrous, slanted, or irregularly curved wisps called mares’ tails.
Civil Air Regulation (CAR)
Predecessor to the Federal Aviation Regulations.
Civil aircraft
Aircraft other than public aircraft.
Civil twilight
The period of time before sunrise and after sunset when the sun is not more than 6° below the horizon.
Class
(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, a classification of aircraft within a category having similar operating characteristics. Examples include: single engine; multiengine; land; water; gyroplane; helicopter; airship; and free balloon; and
(2) As used with respect to the certification of aircraft, a broad grouping of aircraft having similar characteristics of propulsion, flight, or landing. Examples include: airplane; rotorcraft; glider; balloon; landplane; and seaplane.
Class A
Generally, that airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska. Unless otherwise authorized, all persons must operate their aircraft under IFR.
Class A airspace
Airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska; and designated international airspace beyond 12 NM of the coast of the 48 contiguous states and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied.
Class B
Generally, that airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of airport operations or passenger enplanements. The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers (some Class B airspaces areas resemble upside-down wedding cakes), and is designed to contain all published instrument procedures once an aircraft enters the airspace. An ATC clearance is required for all aircraft to operate in the area, and all aircraft that are so cleared receive separation services within the airspace. The cloud clearance requirement for VFR operations is “clear of clouds.”
Class B airspace
Airspace from the surface to 10,000 feet MSL surrounding the nations busiest airports in terms of IFR operations or passenger numbers. The configuration of each Class B airspace is individually tailored and consists of a surface area and two or more layers, and is designed to contain all published instrument procedures once an aircraft enters the airspace. For all aircraft, an ATC clearance is required to operate in the area, and aircraft so cleared receive separation services within the airspace.
Class B Service
This service provides, in addition to basic radar service, approved separation of aircraft based on IFR, VFR, and/or weight, and sequencing of VFR arrivals to the primary airport(s).
Class C
Generally, that airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each Class C area is individually tailored, the airspace usually consists of a surface area with a 5 nautical mile (NM) radius, a circle with a 10NM radius that extends no lower than 1,200 feet up to 4,000 feet above the airport elevation and an outer area that is not charted. Each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while within the airspace. VFR aircraft are only separated from IFR aircraft within the airspace.
Class C airspace
Airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports having an operational control tower, serviced by radar approach control, and having a certain number of IFR operations or passenger numbers. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends from 1,200 feet to 4,000 feet above the airport elevation.
Class C Service
This service provides, in addition to basic radar service, approved separation between IFR and VFR aircraft, and sequencing of VFR aircraft, and sequencing of VFR arrivals to the primary airport.
Class D
Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace will normally be designed to contain the procedures. Arrival extensions for instrument approach procedures may be Class D or Class E airspace. Unless otherwise authorized, each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace. No separation services are provided to VFR aircraft.
Class D airspace
Airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored, and when instrument procedures are published, the airspace is normally designed to contain the procedures.
Class E
Generally, if the airspace is not Class A, Class B, Class C, or Class D, and it is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are Federal airways, airspace beginning at either 700 or 1,200 feet AGL used to transition to/from the terminal or en route environment, en route domestic, and offshore airspace areas designated below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500 MSL over the United States, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska, up to, but not including 18,000 feet MSL, and the airspace above FL 600.
Class E airspace
Airspace that is not Class A, Class B, Class C, or Class D, and is controlled airspace.
Class G airspace
Airspace that is uncontrolled, except when associated with a temporary control tower, and has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.
Clean configuration
A configuration in which all flight control surfaces have been placed to create minimum drag. In most aircraft this means flaps and gear retracted.
Clear Air Turbulence
Turbulence not associated with any visible moisture.
Clear Air Turbulence (CAT)
Turbulence encountered in air where no clouds are present. This term is commonly applied to high-level turbulence associated with wind shear. CAT is often encountered in the vicinity of the jet stream.
Clear ice
Glossy, clear, or translucent ice formed by the relatively slow freezing of large, supercooled water droplets.
Clear icing (or clear ice)
Generally, the formation of a layer or mass of ice which is relatively transparent because of its homogeneous structure and small number and size of air spaces; used commonly as synonymous with glaze, particularly with respect to aircraft icing. Compare with rime icing. Factors which favor clear icing are large drop size, such as those found in cumuliform clouds, rapid accretion of supercooled water, and slow dissipation of latent heat of fusion.
Clear Of The Runway
A. Taxiing aircraft, which is approaching a runway, is clear of the runway when all parts of the aircraft are held short of the applicable runway holding position marking.
B. A pilot or controller may consider an aircraft, which is exiting or crossing a runway, to be clear of the runway when all parts of the aircraft are beyond the runway edge and there are no restrictions to its continued movement beyond the applicable runway holding position marking.
C. Pilots and controllers shall exercise good judgement to ensure that adequate separation exists between all aircraft on runways and taxiways at airports with inadequate runway edge lines or holding position markings.
Clearance
ATC permission for an aircraft to proceed under specified traffic conditions within controlled airspace, for the purpose of providing separation between known aircraft.
Clearance delivery
Control tower position responsible for transmitting departure clearances to IFR flights.
Clearance limit
The fix, point, or location to which an aircraft is cleared when issued an air traffic clearance.
Clearance Limit [ICAO]
The point of which an aircraft is granted an air traffic control clearance.
Clearance on request
An IFR clearance not yet received after filing a flight plan.
Clearance Void If Not Off By (Time)
Used by ATC to advise an aircraft that the departure clearance is automatically canceled if takeoff is not made prior to a specified time. The pilot must obtain a new clearance or cancel his/her IFR flight plan if not off by the specified time.
Clearance void time
Used by ATC, the time at which the departure clearance is automatically canceled if takeoff has not been made. The pilot must obtain a new clearance or cancel the IFR flight plan if not off by the specified time.
Clearance Void Time [ICAO]
A time specified by an air traffic control unit at which a clearance ceases to be valid unless the aircraft concerned has already taken action to comply therewith.
Cleared (Type Of) Approach
ATC authorization for an aircraft to execute a specific instrument approach procedure to an airport; e.g., “Cleared ILS Runway Three Six Approach.”
Cleared Approach
ATC authorization for an aircraft to execute any standard or special instrument approach procedure for that airport. Normally, an aircraft will be cleared for a specific instrument approach procedure.
Cleared As Filed
Means the aircraft is cleared to proceed in accordance with the route of flight filed in the flight plan. This clearance does not include the altitude, DP, or DP Transition.
Cleared For Takeoff
ATC authorization for an aircraft to depart. It is predicated on known traffic and known physical airport conditions.
Cleared For The Option
ATC authorization for an aircraft to make a touch-and-go, low approach, missed approach, stop and go, or full stop landing at the discretion of the pilot. It is normally used in training so that an instructor can evaluate a student’s performance under changing situations.
Cleared Through
ATC authorization for an aircraft to make intermediate stops at specified airports without refiling a flight plan while en route to the clearance limit.
Cleared To Land
ATC authorization for an aircraft to land. It is predicated on known traffic and known physical airport conditions.
Clearway
(1) For turbine engine powered airplanes certificated after August 29, 1959, an area beyond the runway, not less than 500 feet wide, centrally located about the extended centerline of the runway, and under the control of the airport authorities. The clearway is expressed in terms of a clearway plane, extending from the end of the runway with an upward slope not exceeding 1.25 percent, above which no object nor any terrain protrudes. However, threshold lights may protrude above the plane if their height above the end of the runway is 26 inches or less and if they are located to each side of the runway.
(2) For turbine engine powered airplanes certificated after September 30, 1958, but before August 30, 1959, an area beyond the takeoff runway extending no less than 300 feet on either side of the extended centerline of the runway, at an elevation no higher than the elevation of the end of the runway, clear of all fixed obstacles, and under the control of the airport authorities.
Climate
The statistical collective of the weather conditions of a point or area during a specified interval of time (usually several decades); may be expressed in a variety of ways.
Climatology
The study of climate.
Climb Gradient
The ratio between distance traveled and altitude gained.
Climb To VFR
ATC authorization for an aircraft to climb to VFR conditions within Class B, C, D, and E surface areas when the only weather limitation is restricted visibility. The aircraft must remain clear of clouds while climbing to VFR.
Climbout
That portion of flight operation between takeoff and the initial cruising altitude.
Climbout speed
With respect to rotorcraft, a referenced airspeed which results in a flight path clear of the height-velocity envelope during initial climbout.
Clinometer
An instrument used in weather observing for measuring angles of inclination; it is used in conjunction with a ceiling light to determine cloud height at night.
Close Parallel Runways
Two parallel runways whose extended centerlines are separated by less than 4,300 feet, having a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.
Closed Runway
A runway that is unusable for aircraft operations. Only the airport management/military operations office can close a runway.
Closed Traffic
Successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern.
Cloud
A cloud is a visible accumulation of minute water droplets and/or ice particles in the atmosphere above the Earth’s surface. Cloud differs from ground fog, fog, or ice fog only in that the latter are, by definition, in contact with the Earth’s surface.
Cloud bank
Generally, a fairly well-defined mass of cloud observed at a distance; it covers an appreciable portion of the horizon sky, but does not extend overhead.
Cloud cap
Also called a cap cloud. A standing or stationary cap-like cloud crowning a mountain summit.
Cloud detection radar
A vertically directed radar to detect cloud bases and tops.
Cloudburst
In popular terminology, any sudden and heavy fall of rain, almost always of the shower type.
Clutter
In radar operations, clutter refers to the reception and visual display of radar returns caused by precipitation, chaff, terrain, numerous aircraft targets, or other phenomena. Such returns may limit or preclude ATC from providing services based on radar.
Coastal Air Defense Identification Zone
An ADIZ over the coastal waters of the United States.
Coastal Fix
A navigation aid or intersection where an aircraft transitions between the domestic route structure and the oceanic route structure.
Cockpit display of traffic information (CDTI)
The display and user interface for information about air traffic within approximately 80 miles. It will typically combine and show traffic data from TCAS, TIS-B, and ADS-B. Depending on features, the display may also show terrain, weather, and navigation information.
Cockpit Resource Management
Techniques designed to reduce pilot errors and manage errors that do occur utilizing cockpit human resources. The assumption is that errors are going to happen in a complex system with error-prone humans.
Codes
The number assigned to a particular multiple pulse reply signal transmitted by a transponder.
Coefficient Of Lift
See Lift Coefficient.
Coffin Corner
The flight regime where any increase in airspeed will induce high speed mach buffet and any decrease in airspeed will induce low speed mach buffet.
Cognitive domain
A grouping of levels of learning associated with mental activity. In order of increasing complexity, the domains are knowledge, comprehension, application, analysis, synthesis, and evaluation.
Cold front
Any non-occluded front which moves in such a way that colder air replaces warmer air.
Collision Hazard
A condition, event, or circumstance that could induce an occurrence of a collision or surface accident or incident.
Columns
See Database Columns
Combined Center-Rapcon
An air traffic facility which combines the functions of an ARTCC and a radar approach control facility.
Combustion Chamber
The section of the engine into which fuel is injected and burned.
Commercial operator
A person who, for compensation or hire, engages in the carriage by aircraft in air commerce of persons or property, other than as an air carrier or foreign air carrier or under the authority of Part 375 of this title. Where it is doubtful that an operation is for “compensation or hire”, the test applied is whether the carriage by air is merely incidental to the person’s other business or is, in itself, a major enterprise for profit.
Common ARTS
Includes ARTS IIE, ARTS IIIE; and ARTS IIIE with ACD (see DTAS) which combines functionalities of the previous ARTS systems.
Common Point
A significant point over which two or more aircraft will report passing or have reported passing before proceeding on the same or diverging tracks. To establish/maintain longitudinal separation, a controller may determine a common point not originally in the aircraft’s flight plan and then clear the aircraft to fly over the point.
Common Portion
Common Route.
Common Route
That segment of a North American Route between the inland navigation facility and the coastal fix.
Common Traffic Advisory Frequency
The common frequency used by airport traffic to announce position reports in the vicinity of the airport.
Common Traffic Advisory Frequency (CTAF)
A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.
Compact disk (CD)
A small plastic optical disk which contains recorded music or computer data. Also, a popular format for storing information digitally. The major advantage of a CD is its capability to store enormous amounts of information.
Compass course
A true course corrected for variation and deviation errors.
Compass locator
A low-power, low- or medium-frequency (L/MF) radio beacon installed at the site of the outer or middle marker of an ILS.
Compass rose
A small circle graduated in 360 increments, printed on navigational charts to show the amount of compass variation at different locations, or on instruments to indicate direction.
Complex Aircraft
An aircraft with retractable landing gear, flaps, and a controllable-pitch propeller, or is turbine powered.
Comply With Restrictions
An ATC instruction that requires an aircraft being vectored back onto an arrival or departure procedure to comply with all altitude and/or speed restrictions depicted on the procedure. This term may be used in lieu of repeating each remaining restriction that appears on the procedure.
Composite Flight Plan
A flight plan which specifies VFR operation for one portion of flight and IFR for another portion. It is used primarily in military operations.
Composite Route System
An organized oceanic route structure, incorporating reduced lateral spacing between routes, in which composite separation is authorized.
Composite Separation
A method of separating aircraft in a composite route system where, by management of route and altitude assignments, a combination of half the lateral minimum specified for the area concerned and half the vertical minimum is applied.
Comprehensiveness
The degree to which a test measures the overall objective.
Compression Ratio
1. In a reciprocating engine, the ratio of the volume of an engine cylinder with the piston at the bottom center to the volume with the piston at top center. 2. In a turbine engine, the ratio of the pressure of the air at the discharge to the pressure of air at the inlet.
Compressor Bleed Air
See Bleed Air.
Compressor Bleed Valves
See Bleed Valve.
Compressor pressure ratio
The ratio of compressor discharge pressure to compressor inlet pressure.
Compressor Section
The section of a turbine engine that increases the pressure and density of the air flowing through the engine.
Compressor Stall
In gas turbine engines, a condition in an axial-flow compressor in which one or more stages of rotor blades fail to pass air smoothly to the succeeding stages. A stall condition is caused by a pressure ratio that is incompatible with the engine r.p.m. Compressor stall will be indicated by a rise in exhaust temperature or r.p.m. fluctuation, and if allowed to continue, may result in flameout and physical damage to the engine.
Compressor Surge
A severe compressor stall across the entire compressor that can result in severe damage if not quickly corrected. This condition occurs with a complete stoppage of airflow or a reversal of airflow.
Compulsory Reporting Points
Reporting points which must be reported to ATC. They are designated on aeronautical charts by solid triangles or filed in a flight plan as fixes selected to define direct routes. These points are geographical locations which are defined by navigation aids/fixes. Pilots should discontinue position reporting over compulsory reporting points when informed by ATC that their aircraft is in “radar contact.”
Computer navigation fix
A point used to define a navigation track for an airborne computer system such as GPS or FMS.
Computer-assisted instruction
Instruction in which the instructor is responsible for the class and uses the computer to assist in the instruction.
Computer-based training (CBT)
The use of the computer as a training device. CBT is sometimes called computer-based instruction (CBI); the terms and acronyms are synonymous and may be used interchangeably.
Concentric rings
Dashed-line circles depicted in the plan view of IAP charts, outside of the reference circle, that show en route and feeder facilities.
Condensation
The change of water vapor to liquid water.
Condensation level
The height at which a rising parcel or layer of air would become saturated if lifted adiabatically.
Condensation nuclei
Small particles in the air on which water vapor condenses or sublimates.
Condensation trail (or contrail) (also called vapor trail)
A cloud-like streamer frequently observed to form behind aircraft flying in clear, cold, humid air.
Condition
The second part of a performance-based objective which describes the framework under which the skill or behavior will be demonstrated.
Condition Lever
In a turbine engine, a powerplant control that controls the flow of fuel to the engine. The condition lever sets the desired engine r.p.m. within a narrow range between that appropriate for ground and flight operations.
Conditionally unstable air
Unsaturated air that will become unstable on the condition it becomes saturated.
Conduction
The transfer of heat by molecular action through a substance or from one substance in contact with another; transfer is always from warmer to colder temperature.
Cone of confusion
A cone-shaped volume of airspace directly above a VOR station where no signal is received, causing the CDI to fluctuate.
Confidence Maneuver
A confidence maneuver consists of one or more turns, a climb or descent, or other maneuver to determine if the pilot in command (PIC) is able to receive and comply with ATC instructions.
Configuration
This is a general term, which normally refers to the position of the landing gear and flaps.
Configuration, Maintenance, and Procedures (CMP) document
A document approved by the FAA that contains minimum configuration, operating, and maintenance requirements, hardware life-limits, and Master Minimum Equipment List (MMEL) constraints necessary for an airplane-engine combination to meet ETOPS type design approval requirements.
Conflict Alert
A function of certain air traffic control automated systems designed to alert radar controllers to existing or pending situations between tracked targets (known IFR or VFR aircraft) that require his/her immediate attention/action.
Conflict Resolution
The resolution of potential conflictions between aircraft that are radar identified and in communication with ATC by ensuring that radar targets do not touch. Pertinent traffic advisories shall be issued when this procedure is applied. Note: This procedure shall not be provided utilizing mosaic radar systems.
Conformance
The condition established when an aircraft’s actual position is within the conformance region constructed around that aircraft at its position, according to the trajectory associated with the aircraft’s Current Plan.
Conformance Region
A volume, bounded laterally, vertically, and longitudinally, within which an aircraft must be at a given time in order to be in conformance with the Current Plan Trajectory for that aircraft. At a given time, the conformance region is determined by the simultaneous application of the lateral, vertical, and longitudinal conformance bounds for the aircraft at the position defined by time and aircraft’s trajectory.
Confusion between the symbol and the symbolized object.
Results when a word is confused with what it is meant to represent. Words and symbols create confusion when they mean different things to different people.
Consensus standard
For the purpose of certificating light-sport aircraft, an industry-developed consensus standard that applies to aircraft design, production, and airworthiness. It includes, but is not limited to, standards for aircraft design and performance, required equipment, manufacturer quality assurance systems, production acceptance test procedures, operating instructions, maintenance and inspection procedures, identification and recording of major repairs and major alterations, and continued airworthiness.
Consolan
A low frequency, long-distance NAVAID used principally for transoceanic navigations.
Constant pressure chart
A chart of a constant pressure surface; may contain analyses of height, wind, temperature, humidity, and/or other elements.
Constant Speed Propeller
A controllable pitch propeller whose pitch is automatically varied in flight by a governor to maintain a constant r.p.m. in spite of varying air loads.
Constant-speed propeller
A controllable-pitch propeller whose pitch is automatically varied in flight by a governor to maintain a constant rpm in spite of varying air loads.
Contact
A. Establish communication with (followed by the name of the facility and, if appropriate, the frequency to be used).
B. A flight condition wherein the pilot ascertains the attitude of his/her aircraft and navigates by visual reference to the surface.
Contact Approach
An approach where an aircraft on an IFR flight plan, having an air traffic control authorization, operating clear of clouds with at least one mile flight visibility, and a reasonable expectation of continuing to the destination airport in those conditions, may deviate from the instrument approach procedure and proceed to the destination airport by visual reference to the surface. This approach will only be authorized when requested by the pilot and the reported ground visibility at the destination airport is at least one statute mile.
Contaminated Runway
A runway is considered contaminated whenever standing water, ice, snow, slush, frost in any form, heavy rubber, or other substances are present. A runway is contaminated with respect to rubber deposits or other friction-degrading substances when the average friction value for any 500-foot segment of the runway within the ALD fails below the recommended minimum friction level and the average friction value in the adjacent 500-foot segments falls below the maintenance planning friction level.
Conterminous U.S.
The 48 adjoining States and the District of Columbia.
Continental polar air
Also called polar air. An air mass with characteristics developed over high latitudes, especially within the subpolar highs. Continental polar air (cP) has cold surface temperatures, low moisture content, and, especially in its source regions, has great stability in the lower layers. It is shallow in comparison with Arctic air.
Continental tropical air
Also called tropical air. An air mass with characteristics developed over low latitudes. Continental tropical (cT) is produced over subtropical arid regions and is hot and very dry.
Continental United States
The 49 States located on the continent of North America and the District of Columbia.
Continue
When used as a control instruction should be followed by another word or words clarifying what is expected of the pilot. Example: “continue taxi,” “continue descent,” “continue inbound,” etc.
Continuous flow oxygen system
System that supplies a constant supply of pure oxygen to a rebreather bag that dilutes the pure oxygen with exhaled gases and thus supplies a healthy mix of oxygen and ambient air to the mask. Primarily used in passenger cabins of commercial airliners.
Contour
In meteorology, (1) a line of equal height on a constant pressure chart; analogous to contours on a relief map; (2) in radar meteorology, a line on a radar scope of equal echo intensity.
Contouring circuit
On weather radar, a circuit which displays multiple contours of echo intensity simultaneously on the plan position indicator or range-height indicator scope. A line on a radar scope of equal echo intensity.
Contrail
Contraction for condensation trail.
Control and performance
A method of attitude instrument flying in which one instrument is used for making attitude changes, and the other instruments are used to monitor the progress of the change.
Control Area [ICAO]
A controlled airspace extending upwards from a specified limit above the earth.
Control display unit
A display interfaced with the master computer, providing the pilot with a single control point for all navigations systems, thereby reducing the number of required flight deck panels.
Control pressures
The amount of physical exertion on the control column necessary to achieve the desired attitude.
Control Sector
An airspace area of defined horizontal and vertical dimensions for which a controller or group of controllers has air traffic control responsibility, normally within an air route traffic control center or an approach control facility. Sectors are established based on predominant traffic flows, altitude strata, and controller workload. Pilot-communications during operations within a sector are normally maintained on discrete frequencies assigned to the sector.
Control Slash
A radar beacon slash representing the actual position of the associated aircraft. Normally, the control slash is the one closest to the interrogating radar beacon site. When ARTCC radar is operating in narrowband (digitized) mode, the control slash is converted to a target symbol.
Control Touch
The ability to sense the action of the airplane and its probable actions in the immediate future, with regard to attitude and speed variations, by sensing and evaluation of varying pressures and resistance of the control surfaces transmitted through the cockpit flight controls.
Controllability
A measure of the response of an aircraft relative to the pilot’s flight control inputs.
Controllable Pitch Propeller
A propeller in which the blade angle can be changed during flight by a control in the cockpit.
Controlled airspace
An airspace of defined dimensions within which ATC service is provided to IFR and VFR flights in accordance with the airspace classification. It includes Class A, Class B, Class C, Class D, and Class E airspace.
Controlled Airspace [ICAO]
An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Note: Controlled airspace is a generic term which covers ATS airspace Classes A, B, C, D, and E.
Controlled Firing Area
A controlled firing area is established to contain activities, which if not conducted in a controlled environment, would be hazardous to nonparticipating aircraft.
Controlled Flight Into Terrain (CFIT)
A situation where a mechanically normally functioning airplane is inadvertently flown into the ground, water, or an obstacle. There are two basic causes of CFIT accidents; both involve flight crew situational awareness. One definition of situational awareness is an accurate perception by pilots of the factors and conditions currently affecting the safe operation of the aircraft and the crew. The causes of CFIT are the flight crews lack of vertical position awareness or their lack of horizontal position awareness in relation to terrain and obstacles.
Controlled Time Of Arrival
Arrival time assigned during a Traffic Management Program. This time may be modified due to adjustments or user options.
Controller
Air Traffic Control Specialist.
Controller Pilot Data Link Communications (CPDLC)
A two-way digital very high frequency (VHF) air/ground communications system that conveys textual air traffic control messages between controllers and pilots.
Controller [ICAO]
A person authorized to provide air traffic control services.
Convection
(l) In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. (2) In meteorology, atmospheric motions that are predominantly vertical, resulting in vertical transport and mixing of atmospheric properties; distinguished from advection.
Convective cloud
Cumuliform. A term descriptive of all convective clouds exhibiting vertical development in contrast to the horizontally extended stratiform types.
Convective condensation level (abbreviated CCL)
The lowest level at which condensation will occur as a result of convection due to surface heating. When condensation occurs at this level, the layer between the surface and the CCL will be thoroughly mixed, temperature lapse rate will be dry adiabatic, and mixing ratio will be constant.
Convective instability
The state of an unsaturated layer of air whose lapse rates of temperature and moisture are such that when lifted adiabatically until the layer becomes saturated, convection is spontaneous.
Convective SIGMET
Weather advisory concerning convective weather significant to the safety of all aircraft, including thunderstorms, hail, and tornadoes.
Convective Significant Meteorological Information
Convective SIGMET.
Convective weather
Unstable, rising air found in cumuliform clouds.
Conventional Landing Gear
Landing gear employing a third rear-mounted wheel. These airplanes are also sometimes referred to as tailwheel airplanes.
Convergence
The condition that exists when the distribution of winds within a given area is such that there is a net horizontal inflow of air into the area. In convergence at lower levels, the removal of the resulting excess is accomplished by an upward movement of air; consequently, areas of low-level convergent winds are regions favorable to the occurrence of clouds and precipitation. Compare with divergence.
Cooperative or group learning
An instructional strategy which organizes students into small groups so that they can work together to maximize their own and each other’s learning.
Coordinated Flight
Application of all appropriate flight and power controls to prevent slipping or skidding in any flight condition.
Coordinates
The intersection of lines of reference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determine position or location.
Coordination
The ability to use the hands and feet together subconsciously and in the proper relationship to produce desired results in the airplane.
Coordination Fix
The fix in relation to which facilities will handoff, transfer control of an aircraft, or coordinate flight progress data. For terminal facilities, it may also serve as a clearance for arriving aircraft.
Copter
Helicopter.
Core Airflow
Air drawn into the engine for the gas generator.
Coriolis force
A deflective force resulting from earth’s rotation; it acts to the right of wind direction in the Northern Hemisphere and to the left in the Southern Hemisphere.
Coriolis illusion
The illusion of rotation or movement in an entirely different axis, caused by an abrupt head movement, while in a prolonged constant rate turn that has ceased stimulating the brains motion sensing system.
Corona
A prismatically colored circle or arcs of a circle with the sun or moon at its center; coloration is from blue inside to red outside (opposite that of a halo); varies in size (much smaller) as opposed to the fixed diameter of the halo; characteristic of clouds composed of water droplets and valuable in differentiating between middle and cirriform clouds.
Corposant
St. Elmo’s Fire. A luminous brush discharge of electricity from protruding objects, such as masts and yardarms of ships, aircraft, lightning rods, steeples, etc., occurring in stormy weather. Also called corposant.
Corrected altitude
Indicated altitude of an aircraft altimeter corrected for the temperature of the column of air below the aircraft, the correction being based on the estimated departure of existing temperature from standard atmospheric temperature; an approximation of true altitude.
Correction
An error has been made in the transmission and the correct version follows.
Correlation
A basic level of learning where the student can associate what has been learned, understood, and applied with previous or subsequent learning.
Coupled ailerons and rudder
Rudder and ailerons are connected with interconnected springs in order to counteract adverse yaw. Can be overridden if it becomes necessary to slip the aircraft.
Coupled Approach
A coupled approach is an instrument approach performed by the aircraft autopilot which is receiving position information and/or steering commands from onboard navigation equipment. In general, coupled nonprecision approaches must be discontinued and flown manually at altitudes lower than 50 feet below the minimum descent altitude, and coupled precision approaches must be flown manually below 50 feet AGL. Note: Coupled and autoland approaches are flown in VFR and IFR. It is common for carriers to require their crews to fly coupled approaches and autoland approaches (if certified) when the weather conditions are less than approximately 4,000 RVR.
Course
The intended direction of flight in the horizontal plane measured in degrees from north.
Course Controlled Airspace
A. The intended direction of flight in the horizontal plane measured in degrees from north. B. The ILS localizer signal pattern usually specified as the front course or the back course. C. The intended track along a straight, curved, or segmented MLS path.
Course of training
A complete series of studies leading to attainment of a specific goal, such as a certificate of completion, graduation, or an academic degree.
Cowl Flaps
Devices arranged around certain air-cooled engine cowlings which may be opened or closed to regulate the flow of air around the engine.
Crab
A flight condition in which the nose of the airplane is pointed into the wind a sufficient amount to counteract a crosswind and maintain a desired track over the ground.
Crazing
Small fractures in aircraft windshields and windows caused from being exposed to the ultraviolet rays of the sun and temperature extremes.
Crew resource management (CRM)
The effective use of all available resources human, hardware, and information.
Crewmember
A person assigned to perform duty in an aircraft during flight time.
Criteria
The third part of a performance-based objective, descriptions of standards that will be used to measure the accomplishment of the objective.
Criterion-referenced testing
System of testing where students are graded against a carefully written, measurable standard or criterion rather than against each other.
Critical Altitude
The maximum altitude under standard atmospheric conditions at which a turbocharged engine can produce its rated horsepower.
Critical Angle Of Attack
The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.
Critical areas
Areas where disturbances to the ILS localizer and glide slope courses may occur when surface vehicles or aircraft operate near the localizer or glide slope antennas.
Critical Engine
The engine whose failure has the most adverse effect on directional control.
Cross (Fix) At (Altitude)
Used by ATC when a specific altitude restriction at a specified fix is required.
Cross (Fix) At Or Above (Altitude)
Used by ATC when an altitude restriction at a specified fix is required. It does not prohibit the aircraft from crossing the fix at a higher altitude than specified; however, the higher altitude may not be one that will violate a succeeding altitude restriction or altitude assignment.
Cross (Fix) At Or Below (Altitude)
Used by ATC when a maximum crossing altitude at a specific fix is required. It does not prohibit the aircraft from crossing the fix at a lower altitude; however, it must be at or above the minimum IFR altitude.
Cross Controlled
A condition where aileron deflection is in the opposite direction of rudder deflection.
Cross-check
The first fundamental skill of instrument flight, also known as scan, the continuous and logical observation of instruments for attitude and performance information.
Crossfeed
A system that allows either engine on a twin-engine airplane to draw fuel from any fuel tank.
Crosswind
A. When used concerning the traffic pattern, the word means “crosswind leg.” B. When used concerning wind conditions, the word means a wind not parallel to the runway or the path of an aircraft.
Crosswind Component
The wind component, measured in knots, at 90° to the longitudinal axis of the runway.
Crosswind Leg
A flight path at right angles to the landing runway off its upwind end.
Cruise
Used in an ATC clearance to authorize a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block of airspace. Climb/descent within the block is to be made at the discretion of the pilot. However, once the pilot starts descent and verbally reports leaving an altitude in the block, he/she may not return to that altitude without additional ATC clearance. Further, it is approval for the pilot to proceed to and make an approach at destination airport and can be used in conjunction with: a. An airport clearance limit at locations with a standard/special instrument approach procedure. The CFRs require that if an instrument letdown to an airport is necessary, the pilot shall make the letdown in accordance with a standard/special instrument approach procedure for that airport, or b. An airport clearance limit at locations that are within/below/outside controlled airspace and without a standard/special instrument approach procedure. Such a clearance is NOT AUTHORIZATION for the pilot to descend under IFR conditions below the applicable minimum IFR altitude nor does it imply that ATC is exercising control over aircraft in Class G airspace; however, it provides a means for the aircraft to proceed to destination airport, descend, and land in accordance with applicable CFRs governing VFR flight operations. Also, this provides search and rescue protection until such time as the IFR flight plan is closed.
Cruise clearance
An ATC clearance issued to allow a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. Also authorizes a pilot to proceed to and make an approach at the destination airport.
Cruise Climb
A climb technique employed by aircraft, usually at a constant power setting, resulting in an increase of altitude as the aircraft weight decreases.
Cruising Altitude
An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.
Cruising Level
Cruising Altitude. An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.
Cruising Level [ICAO]
A level maintained during a significant portion of a flight.
Cumuliform
A term descriptive of all convective clouds exhibiting vertical development in contrast to the horizontally extended stratiform types.
Cumulonimbus
A cumuliform cloud·type; it is heavy and dense, with considerable vertical extent in the form of massive towers; often with tops in the shape of an anvil or massive plume; under the base of cumulonimbus, which often is very dark, there frequently exists virga, precipitation and low ragged clouds (scud), either merged with it or not; frequently accompanied by lightning, thunder, and sometimes hail; occasionally produces a tornado or a waterspout; the ultimate manifestation of the growth of a cumulus cloud, occasionally extending well into the stratosphere.
Cumulonimbus mamma
A cumulonimbus cloud having hanging protuberances, like pouches, festoons, or udders, on the under side of the cloud; usually indicative of severe turbulence.
Cumulus
A cloud in the form of individual detached domes or towers which are usually dense and well defined; develops vertically in the form of rising mounds of which the bulging upper part often resembles a cauliflower; the sunlit parts of these clouds are mostly brilliant white; their bases are relatively dark and nearly horizontal.
Cumulus Clouds
Clouds in the form of detached domes or towers that are usually well defined. Cumulus clouds develop vertically in the form of rising mounds of which the bulging upper part often resembles a cauliflower; the sunlit parts of these clouds are mostly brilliant white. Their bases may be relatively dark and nearly horizontal.
Cumulus fractus
Cumulus clouds ( Clouds in the form of individual detached domes or towers which are usually dense and well defined) in the form of irregular shreds, appearing as if torn; have a clearly ragged appearance; applies only to stratus and cumulus, i.e., cumulus fractus and stratus fractus.
Current Flight Plan [ICAO]
The flight plan, including changes, if any, brought about by subsequent clearances.
Current Icing Product (CIP)
A graphical planning product that combines sensor and numerical model data to provide a three-dimensional diagnosis of the probability and severity of icing, plus the potential for the presence of supercooled large drops (SLD). This product is automatically produced with no human modification. More information can be found on the Aviation Weather Center (AWC) Aviation Digital Data Service (ADDS) Web site.
Current induction
An electrical current being induced into, or generated in, any conductor that is crossed by lines of flux from any magnet.
Current Limiter
A device that limits the generator output to a level within that rated by the generator manufacturer.
Current Plan
The ATC clearance the aircraft has received and is expected to fly.
Curriculum
A set of courses in an area of specialization offered by an educational institution. A curriculum for a pilot school usually includes courses for the various pilot certificates and ratings.
Curtailment
An operator created and FAA-approved operational loading envelope that is more restrictive than the manufacturer’s CG envelope. It ensures that the aircraft will be operated within limits during all phases of flight. Curtailment typically accounts for, but is not limited to, in-flight movement of passengers and crew, service equipment, cargo variation, seating variation, etc.
Cut-away
Model of an object that is built in sections so it can be taken apart to reveal the inner structure.
Cyclogenesis
Any development or strengthening of cyclonic circulation in the atmosphere.
Cyclone
(l) An area of low atmospheric pressure,. which has a closed circulation that is cyclonic, i.e., as viewed from above, the circulation is counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere, undefined at the Equator. Because cyclonic circulation and relatively low atmospheric pressure usually co-exist, in common practice the terms cyclone and low are used interchangeably. Also, because cyclones often are accompanied by inclement (sometimes destructive) weather, they are frequently referred to simply as storms. (2) Frequently misused to denote a tornado. (3) In the Indian Ocean, a tropical cyclone of hurricane or typhoon force.
D-value
Departure of true altitude from pressure altitude; obtained by algebraically subtracting true altitude from pressure altitude; thus it may be plus or minus. On a constant pressure chart, the difference between actual height and standard atmospheric height of a constant pressure surface.
Danger Area [ICAO]
An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times. Note: The term “Danger Area” is not used in reference to areas within the United States or any of its possessions or territories.
Dark adaptation
Physical and chemical adjustments of the eye that make vision possible in relative darkness.
Data Block
Alphanumeric Display.
Database Columns
The spaces for data entry on each record. One column can accommodate one character.
Database Field
The collection of characters needed to define one item of information.
Database Identifier
A specific geographic point in space identified on an aeronautical chart and in an aviation database, officially designated by the controlling state authority or derived by Jeppesen. It has no ATC function and should not be used in filing flight plans nor used when communicating with ATC.
Database Record
A single line of computer data made up of the fields necessary to define fully a single useful piece of data.
Datum (Reference Datum)
An imaginary vertical plane or line from which all measurements of moment arm are taken. The datum is established by the manufacturer. Once the datum has been selected, all moment arms the location of CG range are measured from this point.
Dead reckoning
Navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction and speed, groundspeed, and elapsed time.
Deceleration error
A magnetic compass error that occurs when the aircraft decelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward South.
Decision Altitude (DA)
A specified altitude in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. The term Decision Altitude (DA) is referenced to mean sea level and the term Decision Height (DH)is referenced to the threshold elevation. Even though DH is charted as an altitude above MSL, the U.S. has adopted the term DAas a step toward harmonization of the United States and international terminology. At some point, DA will be published for all future instrument approach procedures with vertical guidance.
Decision Altitude/Decision Height [ICAO]
A specified altitude or height (A/H) in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. Note 1: Decision altitude [DA] is referenced to mean sea level [MSL] and decision height [DH] is referenced to the threshold elevation. Note 2: The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.
Decision Height
With respect to the operation of aircraft, means the height at which a decision must be made during an ILS, MLS, or PAR instrument approach to either continue the approach or to execute a missed approach.
Decision Height (DH)
See Decision Altitude
Decoder
The device used to decipher signals received from ATCRBS transponders to effect their display as select codes.
Decompression Sickness
A condition where the low pressure at high altitudes allows bubbles of nitrogen to form in the blood and joints causing severe pain. Also known as the bends.
Deepening
A decrease in the central pressure of a pressure system; usually applied to a low rather than to a high, although technically, it is acceptable in either sense.
Defense mechanisms
Subconscious ego-protecting reactions to unpleasant situations.
Defense Visual Flight Rules
Rules applicable to flights within an ADIZ conducted under the visual flight rules in 14 CFR Part 91.
Deice
The act of removing ice accumulation from an aircraft structure.
Deicer Boots
Inflatable rubber boots attached to the leading edge of an airfoil. They can be sequentially inflated and deflated to break away ice that has formed over their surface.
Deicing
Removing ice after it has formed.
Delamination
The separation of layers.
Delay Assignment (DAS)
Delays are distributed to aircraft based on the traffic management program parameters. The delay assignment is calculated in 15-minute increments and appears as a table in Traffic Flow Management System (TFMS).
Delay Indefinite (Reason If Known) Expect Further Clearance
Used by ATC to inform a pilot when an accurate estimate of the delay time and the reason for the delay cannot immediately be determined; e.g., a disabled aircraft on the runway, terminal or center area saturation, weather below landing minimums, etc.
Delay Time
The amount of time that the arrival must lose to cross the meter fix at the assigned meter fix time. This is the difference between ACLT and VTA.
Delta
A Greek letter expressed by the symbol ∆ to indicate a change of values. As an example, ∆CG indicates a change (or movement) of the CG.
Delta ∆
This symbol, ∆, means a change in something. ∆CG means a change in the center of gravity location.
Demonstration-performance method
An educational presentation where an instructor first shows the student the correct way to perform an activity and then has the student attempt the same activity.
Density
(l) The ratio of the mass of any substance to the volume it occupies—weight per unit volume. (2) The ratio of any quantity to the volume or area it occupies, i.e., population per unit area, power density.
Density Altitude
This altitude is pressure altitude corrected for variations from standard temperature. When conditions are standard, pressure altitude and density altitude are the same. If the temperature is above standard, the density altitude is higher than pressure altitude. If the temperature is below standard, the density altitude is lower than pressure altitude. This is an important altitude because it is directly related to the airplane’s performance.
Departure Center
The ARTCC having jurisdiction for the airspace that generates a flight to the impacted airport.
Departure Control
A function of an approach control facility providing air traffic control service for departing IFR and, under certain conditions, VFR aircraft.
Departure End of Runway (DER)
The end of runway available for the ground run of an aircraft departure. The end of the runway that is opposite the landing threshold, sometimes referred to as the stop end of the runway.
Departure procedure (DP)
Preplanned IFR ATC departure, published for pilot use, in textual and graphic format.
Departure Sequencing Program
A program designed to assist in achieving a specified interval over a common point for departures.
Departure Time
The time an aircraft becomes airborne.
Deposition
The direct transformation of a gas to a solid state, in which the liquid state is bypassed. Some sources use sublimation to describe this process instead of deposition.
Depression
In meteorology, an area of low pressure; a low or trough. This is usually applied to a certain stage in the development of a tropical cyclone, to migratory lows and troughs, and to upper-level lows and troughs that are only weakly developed.
Descend Via
A descend via clearance instructs you to follow the altitudes published on a STAR. You are not authorized to leave your last assigned altitude unless specifically cleared to do so. If ATC amends the altitude or route to one that is different from the published procedure, the rest of the charted descent procedure is canceled. ATC will assign you any further route, altitude, or airspeed clearances, as necessary.
Descent Speed Adjustments
Speed deceleration calculations made to determine an accurate VTA. These calculations start at the transition point and use arrival speed segments to the vertex.
Description of the skill or behavior
The first part of a performance-based objective which explains the desired outcome of instruction in concrete terms that can be measured.
Designated Pilot Examiner (DPE)
An individual designated by the FAA to administer practical tests to pilot applicants.
Desired Course
Either True Course or Magnetic Course.
Desired Track
The planned or intended track between two waypoints. It is measured in degrees from either magnetic or true north. The instantaneous angle may change from point to point along the great circle track between waypoints.
Determiners
In test items, words which give a clue to the answer. Words such as “always” and “never” are determiners in true-false questions. Since absolutes are rare, such words usually make the statement false.
Detonation
The sudden release of heat energy from fuel in an aircraft engine caused by the fuel-air mixture reaching its critical pressure and temperature. Detonation occurs as a violent explosion rather than a smooth burning process.
Detresfa (Distress Phase) [ICAO]
The code word used to designate an emergency phase wherein there is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance.
Deviation
A magnetic compass error caused by local magnetic fields within the aircraft. Deviation error is different on each heading.
Deviations
A. A departure from a current clearance, such as an off course maneuver to avoid weather or turbulence.
B. Where specifically authorized in the CFRs and requested by the pilot, ATC may permit pilots to deviate from certain regulations.
Dew
Water condensed onto grass and other objects near the ground, the temperatures of which have fallen below the initial dew point temperature of the surface air, but is still above freezing. Compare with frost.
Dew point (or dew-point temperature)
The temperature to which a sample of air must be cooled, while the mixing ratio and barometric pressure remain constant, in order to attain saturation with respect to water.
Dewpoint
The temperature at which air can hold no more water.
DF Approach Procedure
Used under emergency conditions where another instrument approach procedure cannot be executed. DF (Direction Finding) guidance for an instrument approach is given by ATC facilities with DF capability.
DF Fix
The geographical location of an aircraft obtained by one or more direction finders.
DF Guidance
Headings provided to aircraft by facilities equipped with direction finding equipment. These headings, if followed, will lead the aircraft to a predetermined point such as the DF station or an airport. DF guidance is given to aircraft in distress or to other aircraft which request the service. Practice DF guidance is provided when workload permits.
DF Steer
DF (Direction Finding) Guidance. Headings provided to aircraft by facilities equipped with direction finding equipment. These headings, if followed, will lead the aircraft to a predetermined point such as the DF station or an airport. DF guidance is given to aircraft in distress or to other aircraft which request the service. Practice DF guidance is provided when workload permits.
Differential Ailerons
Control surface rigged such that the aileron moving up moves a greater distance than the aileron moving down. The up aileron produces extra parasite drag to compensate for the additional induced drag caused by the down aileron. This balancing of the drag forces helps minimize adverse yaw.
Differential Global Positioning System (DGPS)
A system that improves the accuracy of Global Navigation Satellite Systems (GNSS) by measuring changes in variables to provide satellite positioning corrections.
Differential pressure
A difference between two pressures. The measurement of airspeed is an example of the use of differential pressure.
Diffusion
Reducing the velocity of air causing the pressure to increase.
Digital ATIS (D-ATIS)
An alternative method of receiving ATIS reports by aircraft equipped with datalink services capable of receiving information in the cockpit over their Aircraft Communications Addressing and Reporting System (ACARS) unit.
Digital Target
A computer-generated symbol representing an aircraft’s position, based on a primary return or radar beacon reply, shown on a digital display.
Digital Terminal Automation System (DTAS)
A system where digital radar and beacon data is presented on digital displays and the operational program monitors the system performance on a real-time basis.
Digital-Automatic Terminal Information Service (D-ATIS)
The service provides text messages to aircraft, airlines, and other users outside the standard reception range of conventional ATIS via landline and data link communications to the cockpit. Also, the service provides a computer-synthesized voice message that can be transmitted to all aircraft within range of existing transmitters. The Terminal Data Link System (TDLS) D-ATIS application uses weather inputs from local automated weather sources or manually entered meteorological data together with preprogrammed menus to provide standard information to users. Airports with D-ATIS capability are listed in the Airport/Facility Directory.
Digitized Target
A computer-generated indication shown on an analog radar display resulting from a primary radar return or a radar beacon reply.
Dihedral
The positive acute angle between the lateral axis of an airplane and a line through the center of a wing or horizontal stabilizer. Dihedral contributes to the lateral stability of an airplane.
Diluter-demand oxygen system
An oxygen system that delivers oxygen mixed or diluted with air in order to maintain a constant oxygen partial pressure as the altitude changes.
Direct
Straight line flight between two navigational aids, fixes, points, or any combination thereof. When used by pilots in describing off-airway routes, points defining direct route segments become compulsory reporting points unless the aircraft is under radar contact.
Direct Altitude And Identity Readout
The DAIR System is a modification to the AN/TPX-42 Interrogator System. The Navy has two adaptations of the DAIR System-Carrier Air Traffic Control Direct Altitude and Identification Readout System for Aircraft Carriers and Radar Air Traffic Control Facility Direct Altitude and Identity Readout System for land-based terminal operations. The DAIR detects, tracks, and predicts secondary radar aircraft targets. Targets are displayed by means of computer-generated symbols and alphanumeric characters depicting flight identification, altitude, ground speed, and flight plan data. The DAIR System is capable of interfacing with ARTCCs.
Direct indication
The true and instantaneous reflection of aircraft pitch-and-bank attitude by the miniature aircraft, relative to the horizon bar of the attitude indicator.
Direct question
A question used for follow-up purposes, but directed at a specific individual.
Direct User Access Terminal System (DUATS)
A system that provides current FAA weather and flight plan filing services to certified civil pilots, via personal computer, modem, or telephone access to the system. Pilots can request specific types of weather briefings and other pertinent data for planned flights.
Direction Finder
A radio receiver equipped with a directional sensing antenna used to take bearings on a radio transmitter. Specialized radio direction finders are used in aircraft as air navigation aids. Others are ground-based, primarily to obtain a “fix” on a pilot requesting orientation assistance or to locate downed aircraft. A location “fix” is established by the intersection of two or more bearing lines plotted on a navigational chart using either two separately located Direction Finders to obtain a fix on an aircraft or by a pilot plotting the bearing indications of his/her DF on two separately located ground-based transmitters, both of which can be identified on his/her chart. UDFs receive signals in the ultra high frequency radio broadcast band; VDFs in the very high frequency band; and UVDFs in both bands. ATC provides DF service at those air traffic control towers and flight service stations listed in the Airport/Facility Directory and the DOD FLIP IFR En Route Supplement.
Directional Stability
Stability about the vertical axis of an aircraft, whereby an aircraft tends to return, on its own, to flight aligned with the relative wind when disturbed from that equilibrium state. The vertical tail is the primary contributor to directional stability, causing an airplane in flight to align with the relative wind.
Directly Behind
An aircraft is considered to be operating directly behind when it is following the actual flight path of the lead aircraft over the surface of the earth except when applying wake turbulence separation criteria.
Discontinuity
A zone with comparatively rapid transition of one or more meteorological elements.
Discrete Beacon Code
Discrete Code. [As used in the Air Traffic Control Radar Beacon System (ATCRBS), any one of the 4096 selectable Mode 3/A aircraft transponder codes except those ending in zero zero; e.g., discrete codes: 0010, 1201, 2317, 7777; nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved for radar facilities that are not equipped with discrete decoding capability and for other purposes such as emergencies (7700), VFR aircraft (1200), etc.]
Discrete Code
As used in the Air Traffic Control Radar Beacon System (ATCRBS), any one of the 4096 selectable Mode 3/A aircraft transponder codes except those ending in zero zero; e.g., discrete codes: 0010, 1201, 2317, 7777; nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved for radar facilities that are not equipped with discrete decoding capability and for other purposes such as emergencies (7700), VFR aircraft (1200), etc.
Discrete Frequency
A separate radio frequency for use in direct pilot-controller communications in air traffic control which reduces frequency congestion by controlling the number of aircraft operating on a particular frequency at one time. Discrete frequencies are normally designated for each control sector in en route/terminal ATC facilities. Discrete frequencies are listed in the Airport/Facility Directory and the DOD FLIP IFR En Route Supplement.
Discrimination
The degree to which a test distinguishes the differences between students.
Displaced Threshold
A threshold that is located at a point on the runway other than the designated beginning of the runway.
Distance circle
The circle depicted in the plan view of an IAP chart that typically has a 10 NM radius, within which chart the elements are drawn to scale. (also, reference circle)
Distance Measuring Equipment
Equipment (airborne and ground) used to measure, in nautical miles, the slant range distance of an aircraft from the DME navigational aid.
Distance measuring equipment (DME)
A pulse-type electronic navigation system that shows the pilot, by an instrument-panel indication, the number of nautical miles between the aircraft and a ground station or waypoint.
Distant Early Warning Identification Zone (DEWIZ)
An ADIZ over the coastal waters of the State of Alaska.
Distractors
Incorrect responses to a multiple-choice test item.
Distress
A condition of being threatened by serious and/or imminent danger and of requiring immediate assistance.
Disturbance
In meteorology, applied rather loosely: (1) any low pressure or cyclone, but usually one that is relatively small in size; (2) an area where weather, wind, pressure, etc., show signs of cyclonic development; (3) any deviation in flow or pressure that is associated with a disturbed state of the weather, i.e., cloudiness and precipitation; and (4) any individual circulatory system within the primary circulation of the atmosphere.
Disuse
A theory of forgetting that suggests a person forgets those things that are not used.
Ditching
Emergency landing in water.
Diurnal
Daily, especially pertaining to a cycle completed within a 24-hour period, and which recurs every 24 hours.
Dive Brakes
Speed Brakes.
Divergence
The condition that exists when the distribution of winds within a given area is such that there is a net horizontal flow of air outward from the region. In divergence at lower levels, the resulting deficit is compensated for by subsidence of air from aloft; consequently the air is heated and the relative humidity lowered making divergence a warming and drying process. Low-level divergent regions are areas unfavorable to the occurrence of clouds and precipitation. The opposite of convergence.
Diverse Vector Area
In a radar environment, that area in which a prescribed departure route is not required as the only suitable route to avoid obstacles. The area in which random radar vectors below the MVA/MIA, established in accordance with the TERPS criteria for diverse departures, obstacles and terrain avoidance, may be issued to departing aircraft.
Diverse Vector Area (DVA)
An airport may establish a diverse vector area if it is necessary to vector aircraft below the minimum vectoring altitude to assist in the efficient flow of departing traffic. DVA design requirements are outlined in TERPS and allow for the vectoring of aircraft immediately off the departure end of the runway below the MVA.
Diversion (DVRSN)
Flights that are required to land at other than their original destination for reasons beyond the control of the pilot/company, e.g. periods of significant weather.
DME arc
A flight track that is a constant distance from the station or waypoint.
DME Fix
A geographical position determined by reference to a navigational aid which provides distance and azimuth information. It is defined by a specific distance in nautical miles and a radial, azimuth, or course (i.e., localizer) in degrees magnetic from that aid.
DME Separation
Spacing of aircraft in terms of distances (nautical miles) determined by reference to distance measuring equipment (DME).
DOD Flip
Department of Defense Flight Information Publications used for flight planning, en route, and terminal operations. FLIP is produced by the National Imagery and Mapping Agency (NIMA) for world-wide use. United States Government Flight Information Publications (en route charts and instrument approach procedure charts) are incorporated in DOD FLIP for use in the National Airspace System (NAS).
Doghouse
A turn-and-slip indicator dial mark in the shape of a doghouse.
Doldrums
The equatorial belt of calm or light and variable winds between the two tradewind belts. Compare intertropical convergence zone.
Domestic Air Defense Identification Zone
An ADIZ within the United States along an international boundary of the United States.
Domestic Airspace
Airspace which overlies the continental land mass of the United States plus Hawaii and U.S. possessions. Domestic airspace extends to 12 miles offshore.
Domestic Reduced Vertical Separation Minimum (DRVSM)
Additional flight levels between FL 290 and FL 410 to provide operational, traffic, and airspace efficiency.
Double gimbal
A type of mount used for the gyro in an attitude instrument. The axes of the two gimbals are at right angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.
Downburst
A strong downdraft which induces an outburst of damaging winds on or near the ground. Damaging winds, either straight or curved, are highly divergent. The sizes of downbursts vary from 1/2 mile or less to more than 10 miles. An intense downburst often causes widespread damage. Damaging winds, lasting 5 to 30 minutes, could reach speeds as high as 120 knots.
Downdraft
A relative small scale downward current of air; often observed on the lee side of large objects restricting the smooth flow of the air or in precipitation areas in or near cumuliform clouds.
Downwash
Air deflected perpendicular to the motion of the airfoil.
Downwind Leg
A flight path parallel to the landing runway in the direction opposite to landing. The downwind leg normally extends between the crosswind leg and the base leg.
Drag
An aerodynamic force on a body acting parallel and opposite to the relative wind. The resistance of the atmosphere to the relative motion of an aircraft. Drag opposes thrust and limits the speed of the airplane.
Drag Chute
A parachute device installed on certain aircraft which is deployed on landing roll to assist in deceleration of the aircraft.
Drag Curve
A visual representation of the amount of drag of an aircraft at various airspeeds.
Drift Angle
Angle between heading and track.
Drifting snow
A type of hydrometeor composed of snow particles picked up from the surface, but carried to a height of less than 6 feet.
Drill and practice method
A time-honored training delivery method based on the learning principle that connections are strengthened with practice.
Drizzle
A form of precipitation. Very small water drops that appear to float with the air currents while falling in an irregular path (unlike rain, which falls in a comparatively straight path, and unlike fog droplets which remain suspended in the air).
Dropsonde
A radiosonde dropped by parachute from an aircraft to obtain soundings (measurements) of the atmosphere below.
Dry adiabatic lapse rate
The rate of decrease of temperature with height when unsaturated air is lifted adiabatically (due to expansion as it is lifted to lower pressure).
Dry bulb
A name given to an ordinary thermometer used to determine temperature of the air; also used as a contraction for dry-bulb temperature. Compare wet bulb.
Dry-bulb temperature
The temperature of the air.
Ducted-Fan Engine
An engine-propeller combination that has the propeller enclosed in a radial shroud. Enclosing the propeller improves the efficiency of the propeller.
Due Regard
A phase of flight wherein an aircraft commander of a State-operated aircraft assumes responsibility to separate his/her aircraft from all other aircraft.
Duplex
Transmitting on one frequency and receiving on a separate frequency.
Dust
A type of lithometeor composed of small earthen particles suspended in the atmosphere.
Dust devil
A small, vigorous whirlwind, usually of short duration, rendered visible by dust, sand, and debris picked up from the ground.
Dust storm (also called duster, black blizzard)
An unusual, frequently severe weather condition characterized by strong winds and dust-filled air over an extensive area.
Duster
Same as dust storm—an unusual, frequently severe weather condition characterized by strong winds and dust-filled air over an extensive area.
Dutch Roll
A combination of rolling and yawing oscillations that normally occurs when the dihedral effects of an aircraft are more powerful than the directional stability. Usually dynamically stable but objectionable in an airplane because of the oscillatory nature.
Duty Runway
Runway In Use/Active Runway/Duty Runway.
DVFR Flight Plan
A flight plan filed for a VFR aircraft which intends to operate in airspace within which the ready identification, location, and control of aircraft are required in the interest of national security.
Dynamic
Continuous review, evaluation, and change to meet demands.
Dynamic Hydroplaning
A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When the tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.
Dynamic Load
The actual weight of the aircraft multiplied by the load factor, or the increase in weight caused by acceleration.
Dynamic Magnetic Variation
A field which is simply a computer model calculated value instead of a measured value contained in the record for a waypoint.
Dynamic Restrictions
Those restrictions imposed by the local facility on an “as needed” basis to manage unpredictable fluctuations in traffic demands.
Dynamic Stability
The property of an aircraft that causes it, when disturbed from straight-and level flight, to develop forces or moments that restore the original condition of straight and level.
Early ETOPS
ETOPS type design approval obtained without gaining non-ETOPS service experience on the candidate airplane-engine combination certified for ETOPS.
Echo
In radar, (1) the energy reflected or scattered by a target; (2) the radar scope presentation of the return from a target.
Eddy
A local irregularity of wind in a larger scale wind flow. Small scale eddies produce turbulent conditions.
Eddy current damping
The decreased amplitude of oscillations by the interaction of magnetic fields. In the case of a vertical card magnetic compass, flux from the oscillating permanent magnet produces eddy currents in a damping disk or cup. The magnetic flux produced by the eddy currents opposes the flux from the permanent magnet and decreases the oscillations.
Eddy currents
Current induced in a metal cup or disc when it is crossed by lines of flux from a moving magnet.
Effect
A principle of learning that learning is strengthened when accompanied by a pleasant or satisfying feeling, and that learning is weakened when associated with an unpleasant feeling.
Electrical Bus
A Bus Bar. An electrical power distribution point to which several circuits may be connected. It is often a solid metal strip having a number of terminals installed on it.
Electrohydraulic
Hydraulic control which is electrically actuated.
Electronic Flight Bag (EFB)
An electronic display system intended primarily for cockpit or cabin use. EFB devices can display a variety of aviation data or perform basic calculations (e.g., performance data, fuel calculations, etc.). In the past, some of these functions were traditionally accomplished using paper references or were based on data provided to the flight crew by an airlines flight dispatch function. The scope of the EFB system functionality may also include various other hosted databases and applications. Physical EFB displays may use various technologies, formats, and forms of communication. These devices are sometimes referred to as auxiliary performance computers (APC) or laptop auxiliary performance computers (LAPC).
Electronic flight display (EFD)
For the purpose of standardization, any flight instrument display that uses LCD or other image-producing system (Cathode Ray Tube [CRT], etc.)
Electronic learning (e-learning)
Any type of education that involves an electronic component such as the Internet, a network, a stand-alone computer, CD/DVDs, video conferencing, websites, or e-mail in its delivery.
Element of threat
A perception factor that describes how a person is unlikely to easily comprehend an event if that person is feeling threatened since most of a person’s effort is focused on whatever is threatening them.
Elevator
The horizontal, movable primary control surface in the tail section, or empennage, of an airplane. The elevator is hinged to the trailing edge of the fixed horizontal stabilizer.
Elevator illusion
The sensation of being in a climb or descent, caused by the kind of abrupt vertical accelerations that result from up- or downdrafts.
Ellipsoid of Revolution
The surface that results when an ellipse is rotated about one of its axes.
EM wave
Electromagnetic wave.
Emergency
A distress or urgent condition.
Emergency Locator Transmitter
A small, self-contained radio transmitter that will automatically, upon the impact of a crash, transmit an emergency signal on 121.5, 243.0, or 406.0 MHz.
Emergency Safe Altitudes
Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance in nonmountainous areas and 2,000 feet of obstacle clearance in designated mountainous areas within a 100-mile radius of the navigation facility upon which the procedure is predicated and normally used only in military procedures. These altitudes are identified on published procedures as “Emergency Safe Altitudes.”
Empennage
The section of the airplane that consists of the vertical stabilizer, the horizontal stabilizer, and the associated control surfaces.
Emphasis error
The result of giving too much attention to a particular instrument during the cross-check, instead of relying on a combination of instruments necessary for attitude and performance information.
Empty Weight
The weight of the airframe, engines, all permanently installed equipment, and unusable fuel. Depending upon the part of the federal regulations under which the aircraft was certificated, either the undrainable oil or full reservoir of oil is included.
Empty-field myopia
Induced nearsightedness that is associated with flying at night, in instrument meteorological conditions and/or reduced visibility. With nothing to focus on, the eyes automatically focus on a point just slightly ahead of the airplane.
Empty-weight Center of Gravity (EWCG)
This is the center of gravity of the aircraft in the empty condition, containing only the items specified in the aircraft empty weight. This CG is an essential part of the weight and balance record of the aircraft.
Empty-weight Center of Gravity Range
The distance between the allowable forward and aft empty-weight CG limits.
En Route Air Traffic Control Services
Air traffic control service provided aircraft on IFR flight plans, generally by centers, when these aircraft are operating between departure and destination terminal areas. When equipment, capabilities, and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
En Route Automation System (EAS)
The complex integrated environment consisting of situation display systems, surveillance systems and flight data processing, remote devices, decision support tools, and the related communications equipment that form the heart of the automated IFR air traffic control system. It interfaces with automated terminal systems and is used in the control of en route IFR aircraft.
En Route Charts
Aeronautical Chart.
En Route Descent
Descent from the en route cruising altitude which takes place along the route of flight.
En route facilities ring
Depicted in the plan view of IAP charts, a circle which designates NAVAIDs, fixes, and intersections that are part of the en route low altitude airway structure.
En Route Flight Advisory Service
A service specifically designed to provide, upon pilot request, timely weather information pertinent to his/her type of flight, intended route of flight, and altitude. The FSSs providing this service are listed in the Airport/Facility Directory.
En Route Flight Advisory Service (EFAS)
An en route weather-only AFSS service.
En Route High Altitude Charts
Aeronautical Chart.
En route high-altitude charts
Aeronautical charts for en route instrument navigation at or above 18,000 feet MSL.
En Route Low Altitude Charts
Aeronautical Chart.
En route low-altitude charts
Aeronautical charts for en route IFR navigation below 18,000 feet MSL.
En Route Minimum Safe Altitude Warning
A function of the EAS that aids the controller by providing an alert when a tracked aircraft is below or predicted by the computer to go below a predetermined minimum IFR altitude (MIA).
En Route Obstacle Clearance Areas
Obstacle clearance areas for en route planning are identified as primary, secondary, and turning areas, and they are designed to provide obstacle clearance route protection width for airways and routes.
En Route Spacing Program (ESP)
A program designed to assist the exit sector in achieving the required in-trail spacing.
En Route Transition
A. Conventional STARs/SIDs. The portion of a SID/STAR that connects to one or more en route airway/jet route.
B. RNAV STARs/SIDs. The portion of a STAR preceding the common route or point, or for a SID the portion following, that is coded for a specific en route fix, airway or jet route.
Encoding altimeter
A special type of pressure altimeter used to send a signal to the air traffic controller on the ground, showing the pressure altitude the aircraft is flying.
Engine Pressure Ratio (EPR)
The ratio of turbine discharge pressure divided by compressor inlet pressure that is used as an indication of the amount of thrust being developed by a turbine engine.
Enhanced flight visibility (EFV)
The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent topographical objects may be clearly distinguished and identified by day or night by a pilot using an enhanced flight vision system.
Enhanced flight vision system (EFVS)
An electronic means to provide a display of the forward external scene topography (the natural or manmade features of a place or region especially in a way to show their relative positions and elevation) through the use of imaging sensors, such as a forward looking infrared, millimeter wave radiometry, millimeter wave radar, low light level image intensifying.
Environmental Systems
In an aircraft, the systems, including the supplemental oxygen systems, air conditioning systems, heaters, and pressurization systems, which make it possible for an occupant to function at high altitude.
Equilibrium
A condition that exists within a body when the sum of the moments of all of the forces acting on the body is equal to zero. In aerodynamics, equilibrium is when all opposing forces acting on an aircraft are balanced (steady, unaccelerated flight conditions).
Equipment List
A list of items approved by the FAA for installation in a particular aircraft. The list includes the name, part number, weight, and arm of the component. Installation or removal of an item in the equipment list is considered to be a minor alteration.
Equivalent airspeed
Airspeed equivalent to CAS in standard atmosphere at sea level. As the airspeed and pressure altitude increase, the CAS becomes higher than it should be, and a correction for compression must be subtracted from the CAS.
Equivalent Shaft Horsepower (ESHP)
A measurement of the total horsepower of a turboprop engine, including that provided by jet thrust.
Established
To be stable or fixed on a route, route segment, altitude, heading, etc.
Estimated ceiling
A ceiling classification applied when the ceiling height has been estimated by the observer or has been determined by some other method; but, because of the specified limits of time, distance, or precipitation conditions, a more descriptive classification cannot be applied.
Estimated Elapsed Time [ICAO]
The estimated time required to proceed from one significant point to another.
Estimated Off-Block Time [ICAO]
The estimated time at which the aircraft will commence movement associated with departure.
Estimated Position Error (EPE)
A measure of the current estimated navigational performance. Also referred to as Actual Navigation Performance (ANP).
Estimated Time En Route
The estimated flying time from departure point to destination (lift-off to touchdown).
Estimated Time Of Arrival
The time the flight is estimated to arrive at the gate (scheduled operators) or the actual runway on times for nonscheduled operators.
ETOPS Significant System
An airplane system, including the propulsion system, the failure or malfunctioning of which could adversely affect the safety of an ETOPS flight, or the continued safe flight and landing of an airplane during an ETOPS diversion. Each ETOPS significant system is either an ETOPS group 1 significant system or an ETOPS group 2 significant system.
(1) An ETOPS group 1 Significant System—
(i) Has fail-safe characteristics directly linked to the degree of redundancy provided by the number of engines on the airplane.
(ii) Is a system, the failure or malfunction of which could result in an IFSD, loss of thrust control, or other power loss.
(iii) Contributes significantly to the safety of an ETOPS diversion by providing additional redundancy for any system power source lost as a result of an inoperative engine.
(iv) Is essential for prolonged operation of an airplane at engine inoperative altitudes.
(2) An ETOPS group 2 significant system is an ETOPS significant system that is not an ETOPS group 1 significant system.
Evaporation
The change of liquid water to water vapor.
Execute Missed Approach
Instructions issued to a pilot making an instrument approach which means continue inbound to the missed approach point and execute the missed approach procedure as described on the Instrument Approach Procedure Chart or as previously assigned by ATC. The pilot may climb immediately to the altitude specified in the missed approach procedure upon making a missed approach. No turns should be initiated prior to reaching the missed approach point. When conducting an ASR or PAR approach, execute the assigned missed approach procedure immediately upon receiving instructions to “execute missed approach.”
Exercise
A principle of learning emphasizing that those things most often repeated are best remembered.
Exhaust
The rear opening of a turbine engine exhaust duct. The nozzle acts as an orifice, the size of which determines the density and velocity of the gases as they emerge from the engine.
Exhaust Gas Temperature (EGT)
The temperature of the exhaust gases as they leave the cylinders of a reciprocating engine or the turbine section of a turbine engine.
Exhaust Manifold
The part of the engine that collects exhaust gases leaving the cylinders.
Expanded Service Volume
When ATC or a procedures specialist requires the use of a NAVAID beyond the limitations specified for standard service volume, an expanded service volume (ESV) may be established. See standard service volume.
Expect (Altitude) At (Time) Or (Fix)
Used under certain conditions to provide a pilot with an altitude to be used in the event of two-way communications failure. It also provides altitude information to assist the pilot in planning.
Expect Departure Clearance Time (EDCT)
The runway release time assigned to an aircraft in a traffic management program and shown on the flight progress strip as an EDCT.
Expect Further Clearance (Time)
The time a pilot can expect to receive clearance beyond a clearance limit.
Expect Further Clearance Via (Airways, Routes Or Fixes)
Used to inform a pilot of the routing he/she can expect if any part of the route beyond a short range clearance limit differs from that filed.
Expect-further-clearance (EFC)
The time a pilot can expect to receive clearance beyond a clearance limit.
Expedite
Used by ATC when prompt compliance is required to avoid the development of an imminent situation. Expedite climb/descent normally indicates to a pilot that the approximate best rate of climb/descent should be used without requiring an exceptional change in aircraft handling characteristics.
Explosive decompression
A change in cabin pressure faster than the lungs can decompress. Lung damage is possible.
Extended Operations (ETOPS)
An airplane flight operation, other than an all-cargo operation in an airplane with more than two engines, during which a portion of the flight is conducted beyond a time threshold identified in part 121 or part 135 of this chapter that is determined using an approved one-engine-inoperative cruise speed under standard atmospheric conditions in still air.
Extended over-water operation
(1) With respect to aircraft other than helicopters, an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline; and
(2) With respect to helicopters, an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline and more than 50 nautical miles from an off-shore heliport structure.
External load
A load that is carried, or extends, outside of the aircraft fuselage.
External-load attaching
Means the structural components used to attach an external load to an aircraft, including external-load containers, the backup structure at the attachment points, and any quick-release device used to jettison the external load.
Extratropical low (sometimes called extratropical cyclone, extra
Any cyclone that is not a tropical cyclone, usually referring to the migratory frontal cyclones of middle and high latitudes.
Eye
The roughly circular area of calm or relatively light winds and comparatively fair weather at the center of a well-developed tropical cyclone. A wall cloud marks the outer boundary of the eye.
FAASTeam Program Manager
The person who designs, implements, and evaluates the FAASTeam within the FAA flight standards district office (FSDO) area of responsibility.
FAASTeam Representative
A volunteer within the aviation community who shares technical expertise and professional knowledge as a part of the FAASTeam.
Fahrenheit temperature scale (abbreviated F)
A temperature scale with 32 degrees as the melting point of pure ice and 212 degrees as the boiling point of pure water at standard sea level atmospheric pressure (29.92 inches or 1013.2 millibars).
Fall wind
A cold wind blowing downslope. Fall wind differs from foehn in that the air is initially cold enough to remain relatively cold despite compressional heating during descent.
False Alert
1. Alerts generated by one or more false surface-radar targets that the system has interpreted as real tracks and placed into safety logic. 2. Alerts in which the safety logic software did not perform correctly, based upon the design specifications and the current set of Safety Logic parameters. 3. The alert is generated by surface radar targets caused by moderate or greater precipitation.
False Horizon
An optical illusion where the pilot confuses a row of lights along a road or other straight line as the horizon.
False Start
Hung Start. In gas turbine engines, a condition of normal light off but with r.p.m. remaining at some low value rather than increasing to the normal idle r.p.m. This is often the result of insufficient power to the engine from the starter. In the event of a hung start, the engine should be shut down.
Fast File
A system whereby a pilot files a flight plan via telephone that is tape recorded and then transcribed for transmission to the appropriate air traffic facility. Locations having a fast file capability are contained in the Airport/Facility Directory. (Alaska only.)
Feathered Propeller
A propeller whose blades have been rotated so that the leading and trailing edges are nearly parallel with the aircraft flight path to stop or minimize drag and engine rotation. Normally used to indicate shutdown of a reciprocating or turboprop engine due to malfunction.
Feathering Propeller (Feathered)
A controllable pitch propeller with a pitch range sufficient to allow the blades to be turned parallel to the line of flight to reduce drag and prevent further damage to an engine that has been shut down after a malfunction.
Federal airways
Class E airspace areas that extend upward from 1,200 feet to, but not including, 18,000 feet MSL, unless otherwise specified.
Federal Aviation Administration Safety Team (FAASTeam)
An organization promoting safety standards and the reduction of aircraft related accidents. Each of the eight FAA Flight Standards regions have a dedicated FAASTeam office.
Feeder facilities
Used by ATC to direct aircraft to intervening fixes between the en route structure and the initial approach fix.
Feeder Fix
The fix depicted on Instrument Approach Procedure Charts which establishes the starting point of the feeder route.
Feeder Route
A feeder route is a route depicted on IAP charts to designate courses for aircraft to proceed from the en route structure to the IAF. Feeder routes, also referred to as approach transitions, technically are not considered approach segments but are an integral part of many IAPs.
Ferry Flight
A flight for the purpose of: a. Returning an aircraft to base. b. Delivering an aircraft from one location to another. c. Moving an aircraft to and from a maintenance base. Ferry flights, under certain conditions, may be conducted under terms of a special flight permit.
Field
See Database Field
Field Elevation
Airport Elevation. The highest point of an airport’s usable runways measured in feet from mean sea level.
Filed
Normally used in conjunction with flight plans, meaning a flight plan has been submitted to ATC.
Filed En Route Delay
Any of the following preplanned delays at points/areas along the route of flight which require special flight plan filing and handling techniques. a. Terminal Area Delay. A delay within a terminal area for touch-and-go, low approach, or other terminal area activity. b. Special Use Airspace Delay. A delay within a Military Operations Area, Restricted Area, Warning Area, or ATC Assigned Airspace. c. Aerial Refueling Delay. A delay within an Aerial Refueling Track or Anchor.
Filed Flight Plan
The flight plan as filed with an ATS unit by the pilot or his/her designated representative without any subsequent changes or clearances.
Filling
An increase in the central pressure of a pressure system; opposite of deepening; more commonly applied to a low rather than a high.
Final
Commonly used to mean that an aircraft is on the final approach course or is aligned with a landing area.
Final approach
Part of an instrument approach procedure in which alignment and descent for landing are accomplished.
Final Approach and Takeoff Area (FATO)
The FATO is a defined heliport area over which the final approach to a hover or a departure is made. The touchdown and lift-off area (TLOF) where the helicopter is permitted to land is normally centered in the FATO. A safety area is provided around the FATO.
Final Approach Course
A bearing/radial/track of an instrument approach leading to a runway or an extended runway centerline all without regard to distance.
Final Approach Fix
The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and the lightning bolt symbol for precision approaches; or when ATC directs a lower-than-published glideslope/path intercept altitude, it is the resultant actual point of the glideslope/path intercept.
Final approach fix (FAF)
The fix from which the IFR final approach to an airport is executed, and which identifies the beginning of the final approach segment. An FAF is designated on government charts by a Maltese cross symbol for nonprecision approaches, and a lightning bolt symbol for precision approaches.
Final Approach Point
The point, applicable only to a nonprecision approach with no depicted FAF (such as an on airport VOR), where the aircraft is established inbound on the final approach course from the procedure turn and where the final approach descent may be commenced. The FAP serves as the FAF and identifies the beginning of the final approach segment.
Final Approach Runway Occupancy Signal (FAROS)
The Final Approach Runway Occupancy Signal (FAROS) is an automated safety system designed to notify pilots on approach to land that the runway is occupied or otherwise unsafe for landing. This pilot notification system is an FAA sponsored research and development effort that addresses the high priority safety hazards of runway incursions.
Final Approach Segment
Segments Of An Instrument Approach Procedure.
Final Approach Segment [ICAO]
That segment of an instrument approach procedure in which alignment and descent for landing are accomplished.
Final Approach [ICAO]
That part of an instrument approach procedure which commences at the specified final approach fix or point, or where such a fix or point is not specified. a. At the end of the last procedure turn, base turn or inbound turn of a racetrack procedure, if specified; or b. At the point of interception of the last track specified in the approach procedure; and ends at a point in the vicinity of an aerodrome from which: 1. A landing can be made; or 2. A missed approach procedure is initiated.
Final Approach-IFR
The flight path of an aircraft which is inbound to an airport on a final instrument approach course, beginning at the final approach fix or point and extending to the airport or the point where a circle-to-land maneuver or a missed approach is executed.
Final Controller
The controller providing information and final approach guidance during PAR and ASR approaches utilizing radar equipment.
Final Guard Service
A value added service provided in conjunction with LAA/RAA only during periods of significant and fast changing weather conditions that may affect landing and takeoff operations.
Final Monitor Aid
A high resolution color display that is equipped with the controller alert system hardware/software which is used in the precision runway monitor (PRM) system. The display includes alert algorithms providing the target predictors, a color change alert when a target penetrates or is predicted to penetrate the no transgression zone (NTZ), a color change alert if the aircraft transponder becomes inoperative, synthesized voice alerts, digital mapping, and like features contained in the PRM system.
Final Monitor Controller
Air Traffic Control Specialist assigned to radar monitor the flight path of aircraft during simultaneous parallel and simultaneous close parallel ILS approach operations. Each runway is assigned a final monitor controller during simultaneous parallel and simultaneous close parallel ILS approaches. Final monitor controllers shall utilize the Precision Runway Monitor (PRM) system during simultaneous close parallel ILS approaches.
Final takeoff speed
The speed of the airplane that exists at the end of the takeoff path in the en route configuration with one engine inoperative.
Fire resistant
(1) With respect to sheet or structural members, the capacity to withstand the heat associated with fire at least as well as aluminum alloy in dimensions appropriate for the purpose for which they are used; and
(2) With respect to fluid-carrying lines, fluid system parts, wiring, air ducts, fittings, and powerplant controls, the capacity to perform the intended functions under the heat and other conditions likely to occur when there is a fire at the place concerned.
Fireproof
(1) With respect to materials and parts used to confine fire in a designated fire zone, the capacity to withstand at least as well as steel in dimensions appropriate for the purpose for which they are used, the heat produced when there is a severe fire of extended duration in that zone; and
(2) With respect to other materials and parts, the capacity to withstand the heat associated with fire at least as well as steel in dimensions appropriate for the purpose for which they are used.
First gust
The leading edge of the spreading downdraft, plow wind, from an approaching thunderstorm.
First Tier Center
The ARTCC immediately adjacent to the impacted center.
Fix
A geographical position determined by visual reference to the surface, by reference to one or more radio NAVAIDs, by celestial plotting, or by another navigational device. Note:Fix is a generic name for a geographical position and is referred to as a fix, waypoint, intersection, reporting point, etc.
Fix Balancing
A process whereby aircraft are evenly distributed over several available arrival fixes reducing delays and controller workload.
Fixating
Staring at a single instrument, thereby interrupting the cross-check process.
Fixation
A psychological condition where the pilot fixes attention on a single source of information and ignores all other sources.
Fixed Shaft Turboprop Engine
A turboprop engine where the gas producer spool is directly connected to the output shaft.
Fixed slot
A fixed, nozzle shaped opening near the leading edge of a wing that ducts air onto the top surface of the wing. Its purpose is to increase lift at higher angles of attack.
Fixed-Pitch Propellers
Propellers with fixed blade angles. Fixed-pitch propellers are designed as climb propellers, cruise propellers, or standard propellers.
Flag
A warning device incorporated in certain airborne navigation and flight instruments indicating that: a. Instruments are inoperative or otherwise not operating satisfactorily, or b. Signal strength or quality of the received signal falls below acceptable values.
Flag Alarm
Flag.
Flame resistant
Not susceptible to combustion to the point of propagating a flame, beyond safe limits, after the ignition source is removed.
Flameout
A condition in the operation of a gas turbine engine in which the fire in the engine goes out due to either too much or too little fuel sprayed into the combustors.
Flameout Pattern
An approach normally conducted by a single-engine military aircraft experiencing loss or anticipating loss of engine power or control. The standard overhead approach starts at a relatively high altitude over a runway (“high key”) followed by a continuous 180 degree turn to a high, wide position (“low key”) followed by a continuous 180 degree turn final. The standard straight-in pattern starts at a point that results in a straight-in approach with a high rate of descent to the runway. Flameout approaches terminate in the type approach requested by the pilot (normally fullstop).
Flammable
With respect to a fluid or gas, susceptible to igniting readily or to exploding.
Flap extended speed
The highest speed permissible with wing flaps in a prescribed extended position.
Flaps
Hinged portion of the trailing edge between the ailerons and fuselage. In some aircraft, ailerons and flaps are interconnected to produce full-span “flaperons.” In either case, flaps change the lift and drag on the wing.
Flash resistant
Not susceptible to burning violently when ignited.
Flat Pitch
A propeller configuration when the blade chord is aligned with the direction of rotation.
Fleet Weight
An average weight accepted by the FAA for aircraft of identical make and model that have the same equipment installed. When a fleet weight control program is in effect, the fleet weight of the aircraft can be used rather than every individual aircraft having to be weighed.
Flicker Vertigo
A disorientating condition caused from flickering light off the blades of the propeller.
Flight Check
A call-sign prefix used by FAA aircraft engaged in flight inspection/certification of navigational aids and flight procedures. The word “recorded” may be added as a suffix; e.g., “Flight Check 320 recorded” to indicate that an automated flight inspection is in progress in terminal areas.
Flight configurations
Adjusting the aircraft control surfaces (including flaps and landing gear) in a manner that will achieve a specified attitude.
Flight Director
An automatic flight control system in which the commands needed to fly the airplane are electronically computed and displayed on a flight instrument. The commands are followed by the human pilot with manual control inputs or, in the case of an autopilot system, sent to servos that move the flight controls.
Flight director indicator (FDI)
One of the major components of a flight director system, it provides steering commands that the pilot (or the autopilot, if coupled) follows.
Flight director indicator(FDI)
One of the major components of a flight director system, it provides steering commands that the pilot (or the autopilot, if coupled) follows.
Flight Following
Traffic Advisories.
Flight Idle
Engine speed, usually in the 70-80 percent range, for minimum flight thrust.
Flight Information Region
An airspace of defined dimensions within which Flight Information Service and Alerting Service are provided. a. Flight Information Service. A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights. b. Alerting Service. A service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid and to assist such organizations as required.
Flight Information Region (FIR)
A FIR is an airspace of defined dimensions within which Flight Information Service and Alerting Service are provided. Flight Information Service (FIS) is a service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights. Alerting Service is a service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid, and assist such organizations as required.
Flight Information Service
A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.
Flight Information Service-Broadcast (FIS-B)
A ground broadcast service provided through the ADS-B Broadcast Services network over the UAT data link that operates on 978 MHz. The FIS-B system provides pilots and flight crews of properly equipped aircraft with a cockpit display of certain aviation weather and aeronautical information.
Flight Inspection
Inflight investigation and evaluation of a navigational aid to determine whether it meets established tolerances.
Flight level
A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet. For example, flight level 250 represents a barometric altimeter indication of 25,000 feet; flight level 255, an indication of 25,500 feet.
Flight Level (FL)
A flight level is a level of constant atmospheric pressure related to a reference datum of 29.92 in.Hg. Each flight level is stated in three digits that represents hundreds of feet. For example, FL 250 represents an altimeter indication of 25,000 feet.
Flight Level [ICAO]
A surface of constant atmospheric pressure which is related to a specific pressure datum, 1013.2 hPa (1013.2 mb), and is separated from other such surfaces by specific pressure intervals. Note 1: A pressure type altimeter calibrated in accordance with the standard atmosphere. a. When set to a QNH altimeter setting, will indicate altitude; b. When set to a QFE altimeter setting, will indicate height above the QFE reference datum; and c. When set to a pressure of 1013.2 hPa (1013.2 mb), may be used to indicate flight levels. Note 2: The terms `height’ and `altitude,’ used in Note 1 above, indicate altimetric rather than geometric heights and altitudes.
Flight Line
A term used to describe the precise movement of a civil photogrammetric aircraft along a predetermined course(s) at a predetermined altitude during the actual photographic run.
Flight management system (FMS)
Provides pilot and crew with highly accurate and automatic long-range navigation capability, blending available inputs from long- and short- range sensors.
Flight Management System Procedure
An arrival, departure, or approach procedure developed for use by aircraft with a slant (/) E or slant (/) F equipment suffix.
Flight Management Systems
A computer system that uses a large data base to allow routes to be preprogrammed and fed into the system by means of a data loader. The system is constantly updated with respect to position accuracy by reference to conventional navigation aids. The sophisticated program and its associated data base insures that the most appropriate aids are automatically selected during the information update cycle.
Flight path
The line, course, or track along which an aircraft is flying or is intended to be flown.
Flight patterns
Basic maneuvers, flown by reference to the instruments rather than outside visual cues, for the purpose of practicing basic attitude flying. The patterns simulate maneuvers encountered on instrument flights such as holding patterns, procedure turns, and approaches.
Flight plan
Specified information, relating to the intended flight of an aircraft, that is filed orally or in writing with air traffic control.
Flight Plan Area
The geographical area assigned by regional air traffic divisions to a flight service station for the purpose of search and rescue for VFR aircraft, issuance of NOTAMs, pilot briefing, in-flight services, broadcast, emergency services, flight data processing, international operations, and aviation weather services. Three letter identifiers are assigned to every flight service station and are annotated in AFDs and FAAO JO 7350.8, LOCATION IDENTIFIERS, as tie-in facilities.
Flight Recorder
A general term applied to any instrument or device that records information about the performance of an aircraft in flight or about conditions encountered in flight. Flight recorders may make records of airspeed, outside air temperature, vertical acceleration, engine RPM, manifold pressure, and other pertinent variables for a given flight.
Flight Recorder [ICAO]
Any type of recorder installed in the aircraft for the purpose of complementing accident/incident investigation. Note: See Annex 6 Part I, for specifications relating to flight recorders.
Flight review
A 14 CFR 61.56 requirement designed to assess and update a pilot’s knowledge and skills.
Flight Service Station (FSS)
An air traffic facility which provides pilot briefings, flight plan processing, en route radio communications, search and rescue services, and assistance to lost aircraft and aircraft in emergency situations. FSSs also relay ATC clearances, process Notices to Airmen, broadcast aviation weather and aeronautical information, and notify Customs and Border Protection of transborder flights. In addition, at selected locations, FSSs provide En Route Flight Advisory Service (Flight Watch) and Airport Advisory Service (AAS). In Alaska, designated FSSs also provide TWEB recordings and take weather observations.
Flight simulation training device (FSTD)
A flight simulator or a flight training device.
Flight Standards District Office
An FAA field office serving an assigned geographical area and staffed with Flight Standards personnel who serve the aviation industry and the general public on matters relating to the certification and operation of air carrier and general aviation aircraft. Activities include general surveillance of operational safety, certification of airmen and aircraft, accident prevention, investigation, enforcement, etc.
Flight strips
Paper strips containing instrument flight information, used by ATC when processing flight plans.
Flight Test
A flight for the purpose of: a. Investigating the operation/flight characteristics of an aircraft or aircraft component. b. Evaluating an applicant for a pilot certificate or rating.
Flight time
(1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or
(2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.
Flight training device (FTD)
A replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit replica. It includes the equipment and computer programs necessary to represent aircraft (or set of aircraft) operations in ground and flight conditions having the full range of capabilities of the systems installed in the device as described in part 60 of this chapter and the qualification performance standard (QPS) for a specific FTD qualification level.
Flight training devices (FTDs)
A full-size replica of the instruments, equipment, panels, and controls of an aircraft, or set of aircraft, in an open flight deck area or in an enclosed cockpit. A force (motion) cueing system or visual system is not required.
Flight visibility
The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.
Flight Visibility [ICAO]
The visibility forward from the cockpit of an aircraft in flight.
Flight Watch
A shortened term for use in air-ground contacts to identify the flight service station providing En Route Flight Advisory Service; e.g., “Oakland Flight Watch.”
Flightcrew member
A pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.
Floating
A condition when landing where the airplane does not settle to the runway due to excessive airspeed.
Floating Waypoints
Floating waypoints represent airspace fixes at a point in space not directly associated with a conventional airway. In many cases they may be established for such purposes as ATC metering fixes, holding points, RNAV-direct routing, gateway waypoints, STAR origination points leaving the en route structure, and SID terminating points joining the en route structure.
Floor load limit
The maximum weight the floor can sustain per square inch/foot as provided by the manufacturer.
Flow line
A streamline.
Fly Heading (Degrees)
Informs the pilot of the heading he/she should fly. The pilot may have to turn to, or continue on, a specific compass direction in order to comply with the instructions. The pilot is expected to turn in the shorter direction to the heading unless otherwise instructed by ATC.
Fly Visual To Airport
Published Instrument Approach Procedure Visual Segment.
Fly-By (FB) Waypoint
A waypoint that requires the use of turn anticipation to avoid overshooting the next flight segment.
Fly-By Waypoint
A fly-by waypoint requires the use of turn anticipation to avoid overshoot of the next flight segment.
Fly-Over (FO) Waypoint
A waypoint that precludes any turn until the waypoint is overflown, and is followed by either an intercept maneuver of the next flight segment or direct flight to the next waypoint.
Fly-Over Waypoint
A fly-over waypoint precludes any turn until the waypoint is overflown and is followed by an intercept maneuver of the next flight segment.
Foehn
A warm, dry downslope wind; the warmness and dryness being due to adiabatic compression upon descent; characteristic of mountainous regions. Also known as a Chinook in the Rockies and Santa Ana winds in Southern California and Northern Baja.
Fog
A hydrometeor consisting of numerous minute water droplets and based at the surface; droplets are small enough to be suspended in the earth’s atmosphere indefinitely. (Unlike driv:.le, it does not fall to the surface; differs from cloud only in that a cloud is not based at the surface; distinguished from haze by its wetness and gray color.)
Follow-up question
In the guided discussion method, a question used by an instructor to get the discussion back on track or to get the students to explain something more thoroughly.
Force (F)
The energy applied to an object that attempts to cause the object to change its direction, speed, or motion. In aerodynamics, it is expressed as F, T (thrust), L (lift), W (weight), or D (drag), usually in pounds.
Forecast Icing Conditions
Environmental conditions expected by an NWS or an FAA-approved weather provider to be conducive to the formation of in-flight icing on aircraft.
Forecast Icing Product (FIP)
The FIP examines numerical weather prediction model output to calculate the probability and severity of icing conditions, plus SLD potential. This product is automatically produced with no human modification. More information can be found on the AWC ADDS Web site.
Foreign air carrier
Any person other than a citizen of the United States, who undertakes directly, by lease or other arrangement, to engage in air transportation.
Foreign air commerce
The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation or navigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in the United States and any place outside thereof; whether such commerce moves wholly by aircraft or partly by aircraft and partly by other forms of transportation.
Foreign air transportation
The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft, in commerce between a place in the United States and any place outside of the United States, whether that commerce moves wholly by aircraft or partly by aircraft and partly by other forms of transportation.
Foreign object damage (FOD)
Damage to a gas turbine engine caused by some object being sucked into the engine while it is running. Debris from runways or taxiways can cause foreign object damage during ground operations, and the ingestion of ice and birds can cause FOD in flight.
Form Drag
The part of parasite drag on a body resulting from the integrated effect of the static pressure acting normal to its surface resolved in the drag direction.
Formal lecture
An oral presentation where the purpose is to inform, persuade, or entertain with little or no verbal participation by the listeners.
Formal Runway Use Program
An approved noise abatement program which is defined and acknowledged in a Letter of Understanding between Flight Operations, Air Traffic Service, the airport proprietor, and the users. Once established, participation in the program is mandatory for aircraft operators and pilots as provided for in 14 CFR Section 91.129.
Formation Flight
More than one aircraft which, by prior arrangement between the pilots, operate as a single aircraft with regard to navigation and position reporting. Separation between aircraft within the formation is the responsibility of the flight leader and the pilots of the other aircraft in the flight. This includes transition periods when aircraft within the formation are maneuvering to attain separation from each other to effect individual control and during join-up and breakaway. a. A standard formation is one in which a proximity of no more than 1 mile laterally or longitudinally and within 100 feet vertically from the flight leader is maintained by each wingman. b. Nonstandard formations are those operating under any of the following conditions: 1. When the flight leader has requested and ATC has approved other than standard formation dimensions. 2. When operating within an authorized altitude reservation (ALTRV) or under the provisions of a letter of agreement. 3. When the operations are conducted in airspace specifically designed for a special activity.
Forward Slip
A slip in which the airplane’s direction of motion continues the same as before the slip was begun. In a forward slip, the airplane’s longitudinal axis is at an angle to its flightpath.
Forward wing
A forward lifting surface of a canard configuration or tandem-wing configuration airplane. The surface may be a fixed, movable, or variable geometry surface, with or without control surfaces.
Four Corner Post Configuration
An arrangement of air traffic pathways in a terminal area that brings incoming flights over fixes at four corners of the traffic area, while outbound flights depart between the fixes, thus minimizing conflicts between arriving and departing traffic.
Fractus
Clouds in the form of irregular shreds, appearing as if torn; have a clearly ragged appearance; applies only to stratus and cumulus, i.e., cumulus fractus and stratus fractus.
Free Power Turbine Engine
A turboprop engine where the gas producer spool is on a separate shaft from the output shaft. The free power turbine spins independently of the gas producer and drives the output shaft.
Freeze Calculated Landing Time
A dynamic parameter number of minutes prior to the meter fix calculated time of arrival for each aircraft when the TCLT is frozen and becomes an ACLT (i.e., the VTA is updated and consequently the TCLT is modified as appropriate until FCLT minutes prior to meter fix calculated time of arrival, at which time updating is suspended and an ACLT and a frozen meter fix crossing time (MFT) is assigned).
Freeze Horizon
The time or point at which an aircraft’s STA becomes fixed and no longer fluctuates with each radar update. This setting insures a constant time for each aircraft, necessary for the metering controller to plan his/her delay technique. This setting can be either in distance from the meter fix or a prescribed flying time to the meter fix.
Freeze Speed Parameter
A speed adapted for each aircraft to determine fast and slow aircraft. Fast aircraft freeze on parameter FCLT and slow aircraft freeze on parameter MLDI.
Freeze/Frozen
Terms used in referring to arrivals which have been assigned ACLTs and to the lists in which they are displayed.
Freezing
The change of liquid water to ice.
Freezing Drizzle
Drizzle is precipitation at ground level or aloft in the form of liquid water drops that have diameters less than 0.5 mm and greater than 0.05 mm. Freezing drizzle is water that remains in a liquid form at air temperatures less than 0 °C (supercooled) and can freeze upon contact with objects on the ground or in the air.
Freezing level
A level in the atmosphere at which the temperature is 0° C (32° F).
Freezing Rain
Rain is precipitation at ground level or aloft in the form of liquid water drops which have diameters greater than 0.5 mm. Freezing rain is rain that exists at air temperatures less than 0 °C, remains in liquid form (supercooled), and freezes upon contact with objects on the ground or in the air.
Friction Drag
The part of parasitic drag on a body resulting from viscous shearing stresses over its wetted surface.
Friction Measurement
A measurement of the friction characteristics of the runway pavement surface using continuous self-watering friction measurement equipment in accordance with the specifications, procedures and schedules contained in AC 150/5320-12, Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces.
Frise-Type Aileron
Aileron having the nose portion projecting ahead of the hinge line. When the trailing edge of the aileron moves up, the nose projects below the wing’s lower surface and produces some parasite drag, decreasing the amount of adverse yaw.
Front
A surface, interface, or transition zone of discontinuity between two adjacent air masses of different densities; more simply the boundary between two different air masses.
Frontal zone
A front or zone with a marked increase of density gradient; used to denote that fronts are not truly a “surface” of discontinuity but rather a “zone” of rapid transition of meteorological elements.
Frontogenesis
The initial formation of a front or frontal zone.
Frontolysis
The dissipation of a front.
Frost
Ice crystal deposits formed by sublimation when temperature and dewpoint are below freezing.
Frost (also hoarfrost)
Ice crystal deposits formed by sublimation when temperature and dew point are below freezing.
Fuel Control Unit
The fuel-metering device used on a turbine engine that meters the proper quantity of fuel to be fed into the burners of the engine. It integrates the parameters of inlet air temperature, compressor speed, compressor discharge pressure, and exhaust gas temperature with the position of the cockpit power control lever.
Fuel Dumping
Airborne release of usable fuel. This does not include the dropping of fuel tanks.
Fuel Efficiency
Defined as the amount of fuel used to produce a specific thrust or horsepower divided by the total potential power contained in the same amount of fuel.
Fuel Heaters
A radiator-like device which has fuel passing through the core. A heat exchange occurs to keep the fuel temperature above the freezing point of water so that entrained water does not form ice crystals, which could block fuel flow.
Fuel Injection
A fuel metering system used on some aircraft reciprocating engines in which a constant flow of fuel is fed to injection nozzles in the heads of all cylinders just outside of the intake valve. It differs from sequential fuel injection in which a timed charge of high-pressure fuel is sprayed directly into the combustion chamber of the cylinder.
Fuel Jettison System
A fuel subsystem that allows the flight crew to dump fuel in an emergency to lower the weight of an aircraft to the maximum landing weight if a return to landing is required before sufficient fuel is burned off. This system must allow enough fuel to be jettisoned that the aircraft can still meet the climb requirements specified in 14 CFR part 25.
Fuel Load
The expendable part of the load of the airplane. It includes only usable fuel, not fuel required to fill the lines or that which remains trapped in the tank sumps.
Fuel Remaining
A phrase used by either pilots or controllers when relating to the fuel remaining on board until actual fuel exhaustion. When transmitting such information in response to either a controller question or pilot initiated cautionary advisory to air traffic control, pilots will state the APPROXIMATE NUMBER OF MINUTES the flight can continue with the fuel remaining. All reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance for established fuel gauge system error.
Fuel Siphoning
Unintentional release of fuel caused by overflow, puncture, loose cap, etc.
Fuel Tank Sump
A sampling port in the lowest part of the fuel tank that the pilot can utilize to check for contaminants in the fuel.
Fuel Venting
Fuel Siphoning.
Fulcrum
The point about which a lever balances.
Full flight simulator (FFS)
A replica of a specific type; or make, model, and series aircraft cockpit. It includes the assemblage of equipment and computer programs necessary to represent aircraft operations in ground and flight conditions, a visual system providing an out-of-the-cockpit view, a system that provides cues at least equivalent to those of a three-degree-of-freedom motion system, and has the full range of capabilities of the systems installed in the device as described in part 60 of this chapter and the qualification performance standards (QPS) for a specific FFS qualification level.
Fundamental skills
Pilot skills of instrument cross-check, instrument interpretation, and aircraft control.
Funnel cloud
A tornado cloud or vortex cloud extending downward from the parent cloud but not reaching the ground.
Fuselage
The section of the airplane that consists of the cabin and/or cockpit, containing seats for the occupants and the controls for the airplane.
Gas Generator
The basic power producing portion of a gas turbine engine and excluding such sections as the inlet duct, the fan section, free power turbines, and tailpipe. Each manufacturer designates what is included as the gas generator, but generally consists of the compressor, diffuser, combustor, and turbine.
Gas Turbine Engine
A form of heat engine in which burning fuel adds energy to compressed air and accelerates the air through the remainder of the engine. Some of the energy is extracted to turn the air compressor, and the remainder accelerates the air to produce thrust. Some of this energy can be converted into torque to drive a propeller or a system of rotors for a helicopter.
Gate Hold Procedures
Procedures at selected airports to hold aircraft at the gate or other ground location whenever departure delays exceed or are anticipated to exceed 15 minutes. The sequence for departure will be maintained in accordance with initial call-up unless modified by flow control restrictions. Pilots should monitor the ground control/clearance delivery frequency for engine start/taxi advisories or new proposed start/taxi time if the delay changes.
Gateway Fix
A navigational aid or fix where an aircraft transitions between the domestic route structure and the oceanic route airspace.
General Aviation
That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of public convenience and necessity from the Civil Aeronautics Board and large aircraft commercial operators.
General Aviation [ICAO]
All civil aviation operations other than scheduled air services and nonscheduled air transport operations for remuneration or hire.
Geo Map
The digitized map markings associated with the ASR-9 Radar System.
Geodetic Datum
The reference plane from which geodetic calculations are made. Or, according to ICAO Annex 15, the numerical or geometrical quantity or set of such quantities (mathematical model) that serves as a reference for computing other quantities in a specific geographic region such as the latitude and longitude of a point.
Geographic Position Markings
Geographic Position Markings are located at points along low visibility taxi routes designated in the airport's Surface Movement Guidance Control System (SMGCS) plan. They are used to identify the location of taxiing aircraft during low visibility operations. Low visibility operations are those that occur when the runway visible range (RVR) is below 1200 feet(360m). They are positioned to the left of the taxiway centreline in the direction of taxiing.
Gimbal ring
A type of support that allows an object, such as a gyroscope, to remain in an upright condition when its base is tilted.
Glaze
A coating of ice, generally clear and smooth, formed by freezing of super.cooled water on a surface.
Glide Ratio
The ratio between distance traveled and altitude lost during non-powered flight.
Glide slope (GS)
Part of the ILS that projects a radio beam upward at an angle of approximately 3° from the approach end of an instrument runway. The glide slope provides vertical guidance to aircraft on the final approach course for the aircraft to follow when making an ILS approach along the localizer path.
Glide slope intercept altitude
The minimum altitude of an intermediate approach segment prescribed for a precision approach that ensures obstacle clearance.
Glidepath
The path of an aircraft relative to the ground while approaching a landing.
Glidepath Angle (GPA)
The angular displacement of the vertical guidance path from a horizontal plane that passes through the reference datum point (RDP). This angle is published on approach charts (e.g., 3.00, 3.20, etc.). GPA is sometimes referred to as vertical path angle (VPA).
Glidepath Intercept Altitude
Glideslope Intercept Altitude.
Glidepath [ICAO]
A descent profile determined for vertical guidance during a final approach.
Glider
A heavier-than-air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend principally on an engine.
Glideslope
Provides vertical guidance for aircraft during approach and landing. The glideslope/glidepath is based on the following: a. Electronic components emitting signals which provide vertical guidance by reference to airborne instruments during instrument approaches such as ILS/MLS, or b. Visual ground aids, such as VASI, which provide vertical guidance for a VFR approach or for the visual portion of an instrument approach and landing. c. PAR. Used by ATC to inform an aircraft making a PAR approach of its vertical position (elevation) relative to the descent profile.
Glideslope (GS)
Part of the ILS that projects a radio beam upward at an angle of approximately 3° from the approach end of an instrument runway. The glideslope provides vertical guidance to aircraft on the final approach course for the aircraft to follow when making an ILS approach along the localizer path.
Glideslope intercept altitude
The minimum altitude of an intermediate approach segment prescribed for a precision approach that ensures obstacle clearance.
Global landing system (GLS)
An instrument approach with lateral and vertical guidance with integrity limits (similar to barometric vertical navigation (BRO VNAV).
Global Navigation Satellite System (GNSS)
An umbrella term adopted by the International Civil Aviation Organization (ICAO) to encompass any independent satellite navigation system used by a pilot to perform onboard position determinations from the satellite data.
Global navigation satellite systems (GNSS)
Satellite navigation systems that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few meters using time signals transmitted along a line of sight by radio from satellites.
Global Position System (GPS)
A satellite-based radio positioning, navigation, and time-transfer system.
Global positioning system (GPS)
Navigation system that uses satellite rather than ground-based transmitters for location information.
Go Ahead
Proceed with your message. Not to be used for any other purpose.
Go Around
Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).
Go-Around
Terminating a landing approach.
Go-around power or thrust setting
The maximum allowable in-flight power or thrust setting identified in the performance data.
Goals and values
A perception factor that describes how a person’s perception of an event depends on beliefs. Motivation toward learning is affected by how much value a person puts on education. Instructors who have some idea of the goals and values of their students will be more successful in teaching them.
Goniometer
As used in radio frequency (RF) antenna systems, a direction-sensing device consisting of two fixed loops of wire oriented 90 from each other, which separately sense received signal strength and send those signals to two rotors (also oriented 90) in the sealed direction-indicating instrument. The rotors are attached to the direction-indicating needle of the instrument and rotated by a small motor until minimum magnetic field is sensed near the rotors.
Governing Range
The range of pitch a propeller governor can control during flight.
Governor
A control which limits the maximum rotational speed of a device.
GPS Approach Overlay Program
An authorization for pilots to use GPS avionics under IFR for flying designated existing nonprecision instrument approach procedures, with the exception of LOC, LDA, and SDF procedures.
Gradient
In meteorology, a horizontal decrease in value per unit distance of a parameter in the direction of maximum decrease; most commonly used with pressure, temperature, and moisture.
Graphic Plan Display (GPD)
A view available with URET that provides a graphic display of aircraft, traffic, and notification of predicted conflicts. Graphic routes for Current Plans and Trial Plans are displayed upon controller request.
Graveyard spiral
The illusion of the cessation of a turn while still in a prolonged, coordinated, constant rate turn, which can lead a disoriented pilot to a loss of control of the aircraft.
Great circle route
The shortest distance across the surface of a sphere (the Earth) between two points on the surface.
Gross Navigation Error (GNE)
In the North Atlantic area of operations, a gross navigation error is a lateral separation of more than 25 NM from the centerline of an aircrafts cleared route, which generates an Oceanic Navigation Error Report. This report is also generated by a vertical separation if you are more than 300 feet off your assigned flight level.
Gross Weight
The total weight of a fully loaded aircraft including the fuel, oil, crew, passengers, and cargo.
Ground Adjustable Trim Tab
A metal trim tab on a control surface that is not adjustable in flight. Bent in one direction or another while on the ground to apply trim forces to the control surface.
Ground clutter
Pertaining to radar, a cluster of echoes, generally at short range, reflected from ground targets.
Ground Communication Outlet (GCO)
An unstaffed, remotely controlled ground/ground communications facility. Pilots at uncontrolled airports may contact ATC and AFSS via Very High Frequency (VHF) radio to a telephone connection. This lets pilots obtain an instrument clearance or close a VFR/IFR flight plan.
Ground Controlled Approach
A radar approach system operated from the ground by air traffic control personnel transmitting instructions to the pilot by radio. The approach may be conducted with surveillance radar (ASR) only or with both surveillance and precision approach radar (PAR). Usage of the term “GCA” by pilots is discouraged except when referring to a GCA facility. Pilots should specifically request a “PAR” approach when a precision radar approach is desired or request an “ASR” or “surveillance” approach when a nonprecision radar approach is desired.
Ground Delay Program (GDP)
A traffic management process administered by the ATCSCC; when aircraft are held on the ground. The purpose of the program is to support the TM mission and limit airborne holding. It is a flexible program and may be implemented in various forms depending upon the needs of the AT system. Ground delay programs provide for equitable assignment of delays to all system users.
Ground Effect
A condition of improved performance encountered when an airplane is operating very close to the ground. When an airplane’s wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.
Ground fog
In the United States, a fog that conceals less than 0.6 of the sky and is not contiguous with the base of clouds.
Ground Idle
Gas turbine engine speed usually 60-70 percent of the maximum r.p.m. range, used as a minimum thrust setting for ground operations.
Ground Loop
A sharp, uncontrolled change of direction of an airplane on the ground.
Ground Power Unit (GPU)
A type of small gas turbine whose purpose is to provide electrical power, and/or air pressure for starting aircraft engines. A ground unit is connected to the aircraft when needed. Similar to an aircraft-installed auxiliary power unit.
Ground proximity warning system (GPWS)
A system designed to determine an aircrafts clearance above the Earth and provides limited predictability about aircraft position relative to rising terrain.
Ground Speed
The speed of an aircraft relative to the surface of the earth.
Ground Stop (GS)
The GS is a process that requires aircraft that meet a specific criteria to remain on the ground. The criteria may be airport specific, airspace specific, or equipment specific; for example, all departures to San Francisco, or all departures entering Yorktown sector, or all Category I and II aircraft going to Charlotte. GSs normally occur with little or no warning.
Ground Track
The aircraft’s path over the ground when in flight.
Ground visibility
Prevailing horizontal visibility near the earth’s surface as reported by the United States National Weather Service or an accredited observer.
Ground Visibility [ICAO]
The visibility at an aerodrome as reported by an accredited observer.
Ground-Based Transceiver (GBT)
The ground-based transmitter/receiver (transceiver) receives automatic dependent surveillance-broadcast messages, which are forwarded to an air traffic control facility for processing and display with other radar targets on the plan position indicator (radar display).
Groundspeed
Speed over the ground, either closing speed to the station or waypoint, or speed over the ground in whatever direction the aircraft is going at the moment, depending upon the navigation system used.
Groundspeed (GS)
The actual speed of the airplane over the ground. It is true airspeed adjusted for wind. Groundspeed decreases with a headwind, and increases with a tailwind.
Groundspeed Measurement System
A measurement system for determining the groundspeed of an aircraft during final approach and landing, by measuring at the aircraft the Doppler shift of a radio signal, and/or its modulation components, transmitted by a fixed ground station.
Guided discussion method
An educational presentation typically used in the classroom where the topic to be covered by a group is introduced and the instructor participates only as necessary to keep the group focused on the subject.
Gust
A sudden brief increase in wind; according to U.S. weather observing practice, gusts are reported when the variation in wind speed between peaks and lulls is at least 10 knots.
Gust Penetration Speed
The speed that gives the greatest margin between the high and low mach speed buffets.
Gyrodyne
A rotorcraft whose rotors are normally engine-driven for takeoff, hovering, and landing, and for forward flight through part of its speed range, and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
Gyroplane
A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.
Gyroscopic Precession
An inherent quality of rotating bodies, which causes an applied force to be manifested 90º in the direction of rotation from the point where the force is applied.
Hail
A form of precipitation composed of balls or irregular lumps of ice, always produced by convective clouds which are nearly always cumulonimbus.
Halo
A prismatically colored or whitish circle or arcs of a circle with the sun or moon at its center; coloration, if not white, is from red inside to blue outside (opposite that of a corona); fixed in size with an angular diameter of 22° (common) or 46° (rare); characteristic of clouds composed of ice crystals; valuable in differentiating between cirriform and forms of lower clouds.
Hand Propping
Starting an engine by rotating the propeller by hand.
Handoff
An action taken to transfer the radar identification of an aircraft from one controller to another if the aircraft will enter the receiving controller’s airspace and radio communications with the aircraft will be transferred.
Have Numbers
Used by pilots to inform ATC that they have received runway, wind, and altimeter information only.
Hazardous attitudes
Five aeronautical decision-making attitudes that may contribute to poor pilot judgment: antiauthority, impulsivity, invulnerability, machismo, and resignation.
Hazardous Inflight Weather Advisory Service
Continuous recorded hazardous inflight weather forecasts broadcasted to airborne pilots over selected VOR outlets defined as an HIWAS Broadcast Area. Discontinued on January 8, 2020.
Hazardous Inflight Weather Advisory Service (HIWAS)
Service providing recorded weather forecasts broadcast to airborne pilots over selected VORs. Discontinued on January 8, 2020.
Hazardous Inflight Weather Advisory Service (HIWAS).
Service providing recorded weather forecasts broadcast to airborne pilots over selected VORs. Discontinued on January 8, 2020.
Hazardous Weather Information
Summary of significant meteorological information (SIGMET/WS), convective significant meteorological information (convective SIGMET/WST), urgent pilot weather reports (urgent PIREP/UUA), center weather advisories (CWA), airmen’s meteorological information (AIRMET/WA) and any other weather such as isolated thunderstorms that are rapidly developing and increasing in intensity, or low ceilings and visibilities that are becoming widespread which is considered significant and are not included in a current hazardous weather advisory.
Haze
A type of lithometeor composed of fine dust or salt particles dispersed through a portion of the atmosphere; particles are so small they cannot be felt or individually seen with the naked eye (as compared with the larger particles of dust), but diminish the visibility; distinguished from fog by its bluish or yellowish tinge.
Head-Up Display (HUD)
See Head-Up Guidance System (HGS)
Head-Up Guidance System (HGS)
A system which projects critical flight data on a display positioned between the pilot and the windscreen. In addition to showing primary flight information, the HUD computes an extremely accurate instrument approach and landing guidance solution, and displays the result as a guidance cue for head-up viewing by the pilot.
Heading
The direction in which the nose of the aircraft is pointing during flight.
Heading Bug
A marker on the heading indicator that can be rotated to a specific heading for reference purposes, or to command an autopilot to fly that heading.
Heading Indicator
An instrument which senses airplane movement and displays heading based on a 360º azimuth, with the final zero omitted. The heading indicator, also called a directional gyro, is fundamentally a mechanical instrument designed to facilitate the use of the magnetic compass. The heading indicator is not affected by the forces that make the magnetic compass difficult to interpret.
Headwind Component
The component of atmospheric winds that acts opposite to the aircraft’s flightpath.
Headwork
Required to accomplish a conscious, rational thought process when making decisions. Good decision-making involves risk identification and assessment, information processing, and problem solving.
Heavy
An Aircraft Class Wake Turbulence Separation Minima. Aircraft capable of takeoff weights of 300,000 pounds or more whether or not they are operating at this weight during a particular phase of flight.
Heavy (Aircraft)
Aircraft Classes.
Height Above Airport
The height of the Minimum Descent Altitude above the published airport elevation. This is published in conjunction with circling minimums.
Height above airport (HAA)
The height of the MDA above the published airport elevation.
Height Above Landing
The height above a designated helicopter landing area used for helicopter instrument approach procedures.
Height above landing (HAL)
The height above a designated helicopter landing area used for helicopter instrument approach procedures.
Height Above Touchdown
The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). HAT is published on instrument approach charts in conjunction with all straight-in minimums.
Height Above Touchdown (HAT)
The height of the DA above touchdown zone elevation (TDZE).
Height above touchdown elevation (HAT)
The DA/DH or MDA above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway).
Helicopter
A rotorcraft that, for its horizontal motion, depends principally on its engine-driven rotors.
Helicopter [ICAO]
A heavier-than-air aircraft supported in flight chiefly by the reactions of the air on one or more power-driven rotors on substantially vertical axes.
Helipad
A small, designated area, usually with a prepared surface, on a heliport, airport, landing/takeoff area, apron/ramp, or movement area used for takeoff, landing, or parking of helicopters.
Heliport
An area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters.
Heliport Reference Point (HRP)
The geographic center of a heliport.
Hertz
The standard radio equivalent of frequency in cycles per second of an electromagnetic wave. Kilohertz (kHz) is a frequency of one thousand cycles per second. Megahertz (MHz) is a frequency of one million cycles per second.
HF Communications
High Frequency Communications.
Hierarchy of human needs
A listing by Abraham Maslow of needs, from the most basic to the most fulfilling: physiological, security, belonging, esteem, cognitive and aesthetic, and self-actualization.
High
An area of high barometric pressure, with its attendant system of winds; an anticyclone. Also high pressure system.
High Altitude Redesign (HAR)
A level of non-restrictive routing (NRR) service for aircraft that have all waypoints associated with the HAR program in their flight management systems or RNAV equipage.
High Frequency
The frequency band between 3 and 30 MHz.
High Frequency Communications
High radio frequencies (HF) between 3 and 30 MHz used for air-to-ground voice communication in overseas operations.
High Performance Aircraft
An aircraft with an engine of more than 200 horsepower.
High Speed Exit
High Speed Taxiway.
High Speed Taxiway
A long radius taxiway designed and provided with lighting or marking to define the path of aircraft, traveling at high speed (up to 60 knots), from the runway center to a point on the center of a taxiway. Also referred to as long radius exit or turn-off taxiway. The high speed taxiway is designed to expedite aircraft turning off the runway after landing, thus reducing runway occupancy time.
High Speed Turnoff
High Speed Taxiway.
Highway in the Sky (HITS)
A graphically intuitive pilot interface system that provides an aircraft operator with all of the attitude and guidance inputs required to safely fly an aircraft in close conformance to air traffic procedures.
Histotoxic hypoxia
The inability of cells to effectively use oxygen. Plenty of oxygen is being transported to the cells that need it, but they are unable to use it.
HIWAS Area
Hazardous Inflight Weather Advisory Service. Discontinued on January 8, 2020.
HIWAS Broadcast Area
A geographical area of responsibility including one or more HIWAS outlet areas assigned to an AFSS/FSS for hazardous weather advisory broadcasting. Discontinued on January 8, 2020.
HIWAS Outlet Area
An area defined as a 150 NM radius of a HIWAS outlet, expanded as necessary to provide coverage. Discontinued on January 8, 2020.
Hold For Release
Used by ATC to delay an aircraft for traffic management reasons; i.e., weather, traffic volume, etc. Hold for release instructions (including departure delay information) are used to inform a pilot or a controller (either directly or through an authorized relay) that an IFR departure clearance is not valid until a release time or additional instructions have been received.
Hold In Lieu Of Procedure Turn
A hold in lieu of procedure turn shall be established over a final or intermediate fix when an approach can be made from a properly aligned holding pattern. The hold in lieu of procedure turn permits the pilot to align with the final or intermediate segment of the approach and/or descend in the holding pattern to an altitude that will permit a normal descent to the final approach fix altitude. The hold in lieu of procedure turn is a required maneuver (the same as a procedure turn) unless the aircraft is being radar vectored to the final approach course, when “NoPT” is shown on the approach chart, or when the pilot requests or the controller advises the pilot to make a “straight-in” approach.
Hold Procedure
A predetermined maneuver which keeps aircraft within a specified airspace while awaiting further clearance from air traffic control. Also used during ground operations to keep aircraft within a specified area or at a specified point while awaiting further clearance from air traffic control.
Hold-Short Point
A point on the runway beyond which a landing aircraft with a LAHSO clearance is not authorized to proceed. This point may be located prior to an intersecting runway, taxiway, predetermined point, or approach/departure flight path.
Hold-Short Position Lights
Flashing in-pavement white lights located at specified hold-short points.
Hold-Short Position Marking
The painted runway marking located at the hold-short point on all LAHSO runways.
Hold-Short Position Signs
Red and white holding position signs located alongside the hold-short point.
Holding
A predetermined maneuver that keeps aircraft within a specified airspace while awaiting further clearance from ATC.
Holding Fix
A specified fix identifiable to a pilot by NAVAIDs or visual reference to the ground used as a reference point in establishing and maintaining the position of an aircraft while holding.
Holding pattern
A racetrack pattern, involving two turns and two legs, used to keep an aircraft within a prescribed airspace with respect to a geographic fix. A standard pattern uses right turns; nonstandard patterns use left turns.
Holding Point [ICAO]
A specified location, identified by visual or other means, in the vicinity of which the position of an aircraft in flight is maintained in accordance with air traffic control clearances.
Holding Procedure
Hold Procedure.
Homing
Flying the aircraft on any heading required to keep the needle pointing to the 0 relative bearing position.
Homing [ICAO]
The procedure of using the direction-finding equipment of one radio station with the emission of another radio station, where at least one of the stations is mobile, and whereby the mobile station proceeds continuously towards the other station.
Horizon
The line of sight boundary between the earth and the sky.
Horizontal situation indicator (HSI)
A flight navigation instrument that combines the heading indicator with a CDI, in order to provide the pilot with better situational awareness of location with respect to the courseline.
Horsepower
The term, originated by inventor James Watt, means the amount of work a horse could do in one second. One horsepower equals 550 foot-pounds per second, or 33,000 foot-pounds per minute.
Hot Start
In gas turbine engines, a start which occurs with normal engine rotation, but exhaust temperature exceeds prescribed limits. This is usually caused by an excessively rich mixture in the combustor. The fuel to the engine must be terminated immediately to prevent engine damage.
Hover Check
Used to describe when a helicopter/VTOL aircraft requires a stabilized hover to conduct a performance/power check prior to hover taxi, air taxi, or takeoff. Altitude of the hover will vary based on the purpose of the check.
Hover Taxi
Used to describe a helicopter/VTOL aircraft movement conducted above the surface and in ground effect at airspeeds less than approximately 20 knots. The actual height may vary, and some helicopters may require hover taxi above 25 feet AGL to reduce ground effect turbulence or provide clearance for cargo slingloads.
How Do You Hear Me?
A question relating to the quality of the transmission or to determine how well the transmission is being received.
Human factors
A multidisciplinary field encompassing the behavioral and social sciences, engineering, and physiology, to consider the variables that influence individual and crew performance for the purpose of optimizing human performance and reducing errors.
Human nature
The general psychological characteristics, feelings, and behavioral traits shared by all humans.
Humidity
Water vapor content of the air; may be expressed as specific humidity, relative humidity, or mixing ratio.
Hung Start
In gas turbine engines, a condition of normal light off but with r.p.m. remaining at some low value rather than increasing to the normal idle r.p.m. This is often the result of insufficient power to the engine from the starter. In the event of a hung start, the engine should be shut down.
Hurricane
A tropical cyclone in the Western Hemisphere with winds in excess of 65 knots or 120 km/h.
Hydraulics
The branch of science that deals with the transmission of power by incompressible fluids under pressure.
Hydrometeor
A general term for particles of liquid water or ice such as rain, fog, frost, etc., formed by modification of water vapor in the atmosphere; also water or ice particles lifted from the earth by the wind such as sea spray or blowing snow.
Hydroplaning
A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When the tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.
Hygrograph
The record produced by a continuous-recording hygrometer.
Hygrometer
An instrument for measuring the water vapor content of the air.
Hypemic hypoxia
A type of hypoxia that is a result of oxygen deficiency in the blood, rather than a lack of inhaled oxygen. It can be caused by a variety of factors. Hypemic means “not enough blood.”.
Hyperventilation
Occurs when an individual is experiencing emotional stress, fright, or pain, and the breathing rate and depth increase, although the carbon dioxide level in the blood is already at a reduced level. The result is an excessive loss of carbon dioxide from the body, which can lead to unconsciousness due to the respiratory system’s overriding mechanism to regain control of breathing.
Hypoxia
A lack of sufficient oxygen reaching the body tissues.
Hypoxic hypoxia
This type of hypoxia is a result of insufficient oxygen available to the lungs. A decrease of oxygen molecules at sufficient pressure can lead to hypoxic hypoxia.
I Say Again
The message will be repeated.
Ice crystals
A type of precipitation composed of unbranched crystals in the form of needles, columns, or plates; usually having a very slight downward motion, may fall from a cloudless sky.
Ice fog
A type of fog composed of minute suspended particles of ice; occurs at very low temperatures and may cause halo phenomena.
Ice needles
A form of ice crystals.
Ice pellets
Small, transparent or translucent, round or irregularly shaped pellets of ice. They may be (1) hard grains that rebound on striking a hard surface or (2) pellets of snow encased in ice.
Icing
In general, any deposit of ice forming on an object. Types include clear icing, rime icing, and glaze.
Icing Envelopes
Icing envelopes used for the certification of aircraft for flight in icing conditions specify atmospheric icing conditions in terms of altitude, temperature, Liquid Water Content (LWC), and drop size represented by the Median Volume Diameter (MVD). The envelopes use the term mean effective diameter, but this equates to the MVD for the instrumentation and assumptions current at the time the envelopes were established.) There are two classes of icing envelopes: continuous maximum and intermittent maximum. The continuous maximum is for stratus-type clouds, and the intermittent maximum is for cumulus-type clouds.
Icing Intensity
Trace, Light, Moderate, Severe.
Ident
Air Traffic Control request for a pilot to push the button on the transponder to identify return on the controllers scope.
Ident Feature
The special feature in the Air Traffic Control Radar Beacon System (ATCRBS) equipment. It is used to immediately distinguish one displayed beacon target from other beacon targets.
Idle thrust
The jet thrust obtained with the engine power control level set at the stop for the least thrust position at which it can be placed.
If No Transmission Received For (Time)
Used by ATC in radar approaches to prefix procedures which should be followed by the pilot in event of lost communications.
IFR (Instrument Flight Rules)
Rules that govern the procedure for conducting flight in weather conditions below VFR weather minimums. The term “IFR” also is used to define weather conditions and the type of flight plan under which an aircraft is operating.
IFR Aircraft
An aircraft conducting flight in accordance with instrument flight rules.
IFR conditions
Weather conditions below the minimum for flight under visual flight rules.
IFR Departure Procedure
IFR Takeoff Minimums And Departure Procedures.
IFR Flight
IFR Aircraft.
IFR Landing Minimums
Landing Minimums.
IFR Military Training Routes (IR)
Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training in both IFR and VFR weather conditions below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.
IFR over-the-top
With respect to the operation of aircraft, the operation of an aircraft over-the-top on an IFR flight plan when cleared by air traffic control to maintain “VFR conditions” or “VFR conditions on top”.
IFR Takeoff Minimums And Departure Procedures
Title 14 Code of Federal Regulations Part 91, prescribes standard takeoff rules for certain civil users. At some airports, obstructions or other factors require the establishment of nonstandard takeoff minimums, departure procedures, or both to assist pilots in avoiding obstacles during climb to the minimum en route altitude. Those airports are listed in FAA/DOD Instrument Approach Procedures (IAPs) Charts under a section entitled “IFR Takeoff Minimums and Departure Procedures.” The FAA/DOD IAP chart legend illustrates the symbol used to alert the pilot to nonstandard takeoff minimums and departure procedures. When departing IFR from such airports or from any airports where there are no departure procedures, DPs, or ATC facilities available, pilots should advise ATC of any departure limitations. Controllers may query a pilot to determine acceptable departure directions, turns, or headings after takeoff. Pilots should be familiar with the departure procedures and must assure that their aircraft can meet or exceed any specified climb gradients.
Igniter Plugs
The electrical device used to provide the spark for starting combustion in a turbine engine. Some igniters resemble spark plugs, while others, called glow plugs, have a coil of resistance wire that glows red hot when electrical current flows through the coil.
Illustrated talk
An oral presentation where the speaker relies heavily on visual aids to convey ideas to the listeners.
ILS categories
Categories of instrument approach procedures allowed at airports equipped with the following types of instrument landing systems: ILS Category I: Provides for approach to a height above touchdown of not less than 200 feet, and with runway visual range of not less than 1,800 feet. ILS Category II: Provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet. ILS Category IIIA: Provides for approach without a decision height minimum and with runway visual range of not less than 700 feet. ILS Category IIIB: Provides for approach without a decision height minimum and with runway visual range of not less than 150 feet. ILS Category IIIC: Provides for approach without a decision height minimum and without runway visual range minimum.
ILS Category I
Provides for approach to a height above touchdown of not less than 200 feet, and with runway visual range of not less than 1,800 feet.
ILS Category II
Provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet.
ILS Category IIIA
Provides for approach without a decision height minimum and with runway visual range of not less than 700 feet.
ILS Category IIIB
Provides for approach without a decision height minimum and with runway visual range of not less than 150 feet.
ILS Category IIIC
Provides for approach without a decision height minimum and without runway visual range minimum.
ILS PRM Approach
An instrument landing system (ILS) approach conducted to parallel runways whose extended centerlines are separated by less than 4,300 feet and the parallel runways have a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.
Immediately
Used by ATC or pilots when such action compliance is required to avoid an imminent situation.
Impact Ice
Ice that forms on the wings and control surfaces or on the carburetor heat valve, the walls of the air scoop, or the carburetor units during flight. Impact ice collecting on the metering elements of the carburetor may upset fuel metering or stop carburetor fuel flow.
Impingement
The striking and adherence of a water droplet on an aircraft surface. The impingement rate is the rate at which droplets of a given size collect on a particular surface. In general, impingement rates are higher for larger drops and smaller components, such as a very high frequency (VHF) or a Global Positioning System (GPS) antenna.
In-flight shutdown (IFSD)
For ETOPS only, when an engine ceases to function (when the airplane is airborne) and is shutdown, whether self induced, flightcrew initiated or caused by an external influence. The FAA considers IFSD for all causes: for example, flameout, internal failure, flightcrew initiated shutdown, foreign object ingestion, icing, inability to obtain or control desired thrust or power, and cycling of the start control, however briefly, even if the engine operates normally for the remainder of the flight. This definition excludes the airborne cessation of the functioning of an engine when immediately followed by an automatic engine relight and when an engine does not achieve desired thrust or power but is not shutdown.
Incerfa (Uncertainty Phase) [ICAO]
A situation wherein uncertainty exists as to the safety of an aircraft and its occupants.
Inclinometer
An instrument consisting of a curved glass tube, housing a glass ball, and damped with a fluid similar to kerosene. It may be used to indicate inclination, as a level, or, as used in the turn indicators, to show the relationship between gravity and centrifugal force in a turn.
Increase Speed To (Speed)
Speed Adjustment.
Indefinite ceiling
A ceiling classification denoting vertical visibility into a surface based obscuration.
Index Point
A location specified by the aircraft manufacturer from which arms used in weight and balance computations are measured. Arms measured from the index point are called index arms.
Indicated airspeed
The speed of an aircraft as shown on its pitot static airspeed indicator calibrated to reflect standard atmosphere adiabatic compressible flow at sea level uncorrected for airspeed system errors.
Indicated Airspeed (IAS)
The direct instrument reading obtained from the airspeed indicator, uncorrected for variations in atmospheric density, installation error, or instrument error. Manufacturers use this airspeed as the basis for determining airplane performance. Takeoff, landing, and stall speeds listed in the AFM or POH are indicated airspeeds and do not normally vary with altitude or temperature.
Indicated Altitude
The altitude read directly from the altimeter (uncorrected) when it is set to the current altimeter setting.
Indirect indication
A reflection of aircraft pitch-and-bank attitude by the instruments other than the attitude indicator.
Induced Drag
That part of total drag which is created by the production of lift. Induced drag increases with a decrease in airspeed.
Induction icing
A type of ice in the induction system that reduces the amount of air available for combustion. The most commonly found induction icing is carburetor icing.
Induction Manifold
The part of the engine that distributes intake air to the cylinders.
Inertia
The opposition which a body offers to a change of motion.
Inertial Navigation System
An RNAV system which is a form of self-contained navigation.
Inertial navigation system (INS)
A computer-based navigation system that tracks the movement of an aircraft via signals produced by onboard accelerometers. The initial location of the aircraft is entered into the computer, and all subsequent movement of the aircraft is sensed and used to keep the position updated. An INS does not require any inputs from outside signals.
Inflight Refueling
Aerial Refueling.
Inflight Weather Advisory
Weather Advisory.
Informal Runway Use Program
An approved noise abatement program which does not require a Letter of Understanding, and participation in the program is voluntary for aircraft operators/pilots.
Information Request
A request originated by an FSS for information concerning an overdue VFR aircraft.
Initial Approach
The segment between the initial approach fix and the intermediate fix or the point where the aircraft is established on the intermediate course or final approach course.
Initial Approach Fix
The fixes depicted on instrument approach procedure charts that identify the beginning of the initial approach segment(s).
Initial approach fix (IAF)
The fix depicted on IAP charts where the instrument approach procedure (IAP) begins unless otherwise authorized by ATC.
Initial Approach Segment
Segments Of An Instrument Approach Procedure.
Initial Approach Segment [ICAO]
That segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix or, where applicable, the final approach fix or point.
Initial Climb
This stage of the climb begins when the airplane leaves the ground, and a pitch attitude has been established to climb away from the takeoff area.
Initial Climb Area (ICA)
An area beginning at the departure end of runway (DER) to provide unrestricted climb to at least 400 feet above DER elevation.
Inland Navigation Facility
A navigation aid on a North American Route at which the common route and/or the noncommon route begins or ends.
Inner Marker
A marker beacon used with an ILS (CAT II) precision approach located between the middle marker and the end of the ILS runway, transmitting a radiation pattern keyed at six dots per second and indicating to the pilot, both aurally and visually, that he/she is at the designated decision height (DH), normally 100 feet above the touchdown zone elevation, on the ILS CAT II approach. It also marks progress during a CAT III approach.
Inner Marker Beacon
Inner Marker.
Inner-Approach OFZ
The inner-approach OFZ (Obstacle Free Zone)is a defined volume of airspace centered on the approach area. The inner-approach OFZ applies only to runways with an approach lighting system. The inner-approach OFZ begins 200 feet from the runway threshold at the same elevation as the runway threshold and extends 200 feet beyond the last light unit in the approach lighting system. The width of the inner-approach OFZ is the same as the runway OFZ and rises at a slope of 50 (horizontal) to 1 (vertical) from the beginning.
Inner-Transitional OFZ
The inner transitional surface OFZ (Obstacle Free Zone) is a defined volume of airspace along the sides of the runway and inner-approach OFZ and applies only to precision instrument runways. The inner-transitional surface OFZ slopes 3 (horizontal) to 1 (vertical) out from the edges of the runway OFZ and inner-approach OFZ to a height of 150 feet above the established airport elevation.
Inoperative components
Higher minimums are prescribed when the specified visual aids are not functioning; this information is listed in the Inoperative Components Table found in the United States Terminal Procedures Publications.
Insight
The grouping of perceptions into meaningful wholes. Creating insight is one of the instructor’s major responsibilities.
Insolation
Incoming solar radiation falling upon the earth and its atmosphere.
Instability
A general term to indicate various states of the atmosphere in which spontaneous convection will occur when prescribed criteria are met; indicative of turbulence. Types include: absolute instability, conditionally unstable air, convective instability.
Instantaneous vertical speed indicator (IVSI)
Assists in interpretation by instantaneously indicating the rate of climb or descent at a given moment with little or no lag as displayed in a vertical speed indicator (VSI).
Instructional aids
Devices that assist an instructor in the teaching-learning process. They are supplementary training devices, and are not self-supporting.
Instrument
A device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.
Instrument Approach
Instrument Approach Procedure.
Instrument Approach Procedure
A series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing or to a point from which a landing may be made visually. It is prescribed and approved for a specific airport by competent authority. a. U.S. civil standard instrument approach procedures are approved by the FAA as prescribed under 14 CFR Part 97 and are available for public use. b. U.S. military standard instrument approach procedures are approved and published by the Department of Defense. c. Special instrument approach procedures are approved by the FAA for individual operators but are not published in 14 CFR Part 97 for public use.
Instrument approach procedure (IAP)
A series of predetermined maneuvers by reference to flight instruments with specified protection from obstacles and assurance of navigation signal reception capability. It begins from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point:
(1) From which a landing can be completed; or
(2) If a landing is not completed, to a position at which holding or en route obstacle clearance criteria apply.
Instrument Approach Procedure [ICAO]
A series of predetermined maneuvers by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if a landing is not completed, to a position at which holding or en route obstacle clearance criteria apply.
Instrument approach procedures (IAP)
A series of predetermined maneuvers for the orderly transfer of an aircraft under IFR from the beginning of the initial approach to a landing or to a point from which a landing may be made visually.
Instrument Approach Procedures (IAP) Charts
Portray the aeronautical data which is required to execute an instrument approach to an airport. These charts depict the procedures, including all related data, and the airport diagram. Each procedure is designated for use with a specific type of electronic navigation system including NDB, TACAN, VOR, ILS/MLS, and RNAV. These charts are identified by the type of navigational aid(s) which provide final approach guidance.
Instrument Approach Waypoint
Fixes used in defining RNAV IAPs, including the feeder waypoint (FWP), the initial approach waypoint (IAWP), the intermediate waypoint (IWP), the final approach waypoint (FAWP), the RWY WP, and the APT WP, when required.
Instrument Departure Procedure (DP)
A preplanned instrument flight rule (IFR) departure procedure published for pilot use, in graphic or textual format, that provides obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DP, Obstacle Departure Procedure (ODP), printed either textually or graphically, and, Standard Instrument Departure (SID), which is always printed graphically.
Instrument Departure Procedure (DP) Charts
Designed to expedite clearance delivery and to facilitate transition between takeoff and en route operations. Each DP is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.
Instrument Flight Rules
Rules governing the procedures for conducting instrument flight. Also a term used by pilots and controllers to indicate type of flight plan.
Instrument flight rules (IFR)
Rules and regulations established by the Federal Aviation Administration to govern flight under conditions in which flight by outside visual reference is not safe. IFR flight depends upon flying by reference to instruments in the flight deck, and navigation is accomplished by reference to electronic signals.
Instrument Flight Rules [ICAO]
A set of rules governing the conduct of flight under instrument meteorological conditions.
Instrument Landing System
A precision instrument approach system which normally consists of the following electronic components and visual aids: a. Localizer. b. Glideslope. c. Outer Marker. d. Middle Marker. e. Approach Lights.
Instrument Landing System (ILS)
A precision instrument approach system that normally consists of the following electronic components and visual aids; localizer, glide slope, outer marker, middle marker, and approach lights.
Instrument Meteorological Conditions
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.
Instrument meteorological conditions (IMC)
Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for visual meteorological conditions, requiring operations to be conducted under IFR.
Instrument meteorological conditions (IMC).
Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for visual meteorological conditions, requiring operations to be conducted under IFR.
Instrument Procedure with Vertical Guidance (IPV)
Satellite or Flight Management System (FMS) lateral navigation (LNAV) with computed positive vertical guidance based on barometric or satellite elevation. This term has been renamed APV.
Instrument proficiency check
An evaluation ride based on the instrument rating practical test standard which is required to regain instrument flying privileges when the privileges have expired due to lack of currency.
Instrument Runway
A runway equipped with electronic and visual navigation aids for which a precision or nonprecision approach procedure having straight-in landing minimums has been approved.
Instrument Runway [ICAO]
One of the following types of runways intended for the operation of aircraft using instrument approach procedures: Nonprecision, Precision Category I, Precision Category II, Precision Category III.
Instrument takeoff
Using the instruments rather than outside visual cues to maintain runway heading and execute a safe takeoff.
Integral Fuel Tank
A portion of the aircraft structure, usually a wing, which is sealed off and used as a fuel tank. When a wing is used as an integral fuel tank, it is called a “wet wing.”
Integrated flight instruction
A technique of flight instruction in which students are taught to perform flight maneuvers by reference to both the flight instruments and to outside visual references from the time the maneuver is first introduced. Handling of the controls is the same regardless of whether flight instruments or outside references are being used.
Integrity
The ability of a system to provide timely warnings to users when the system should not be used for navigation.
Intensity
A principle of learning in which a dramatic or exciting learning experience is likely to be remembered longer than a boring experience. Students experiencing the real thing will learn more than when they are merely told about the real thing.
Interactive video
Software that responds quickly to certain choices and commands by the user. A typical system consists of a compact disk, computer, and video technology.
Intercooler
A device used to reduce the temperature of the compressed air before it enters the fuel metering device. The resulting cooler air has a higher density, which permits the engine to be operated with a higher power setting.
Interference
(1) A theory of forgetting proposing that a person forgets something because a certain experience overshadows it, or the learning of similar things has intervened. (2) Barriers to effective communication that are caused by physiological, environmental, and psychological factors outside the direct control of the instructor. The instructor must take these factors into account in order to communicate effectively.
Interference drag
Drag generated by the collision of airstreams creating eddy currents, turbulence, or restrictions to smooth flow.
Intermediate Approach
The segment between the intermediate fix or point and the final approach fix.
Intermediate Approach Segment
Segments Of An Instrument Approach Procedure.
Intermediate Approach Segment [ICAO]
That segment of an instrument approach procedure between either the intermediate approach fix and the final approach fix or point, or between the end of a reversal, race track or dead reckoning track procedure and the final approach fix or point, as appropriate.
Intermediate Fix
The fix that identifies the beginning of the intermediate approach segment of an instrument approach procedure. The fix is not normally identified on the instrument approach chart as an intermediate fix (IF).
Intermediate Landing
On the rare occasion that this option is requested, it should be approved. The departure center, however, must advise the ATCSCC so that the appropriate delay is carried over and assigned at the intermediate airport. An intermediate landing airport within the arrival center will not be accepted without coordination with and the approval of the ATCSCC.
Internal Combustion Engines
An engine that produces power as a result of expanding hot gases from the combustion of fuel and air within the engine itself. A steam engine where coal is burned to heat up water inside the engine is an example of an external combustion engine.
International Airport
Relating to international flight, it means: a. An airport of entry which has been designated by the Secretary of Treasury or Commissioner of Customs as an international airport for customs service. b. A landing rights airport at which specific permission to land must be obtained from customs authorities in advance of contemplated use. c. Airports designated under the Convention on International Civil Aviation as an airport for use by international commercial air transport and/or international general aviation.
International Airport [ICAO]
Any airport designated by the Contracting State in whose territory it is situated as an airport of entry and departure for international air traffic, where the formalities incident to customs, immigration, public health, animal and plant quarantine and similar procedures are carried out.
International Civil Aviation Organization (ICAO)
ICAO is a specialized agency of the United Nations whose objective is to develop standard principles and techniques of international air navigation and to promote development of civil aviation.
International Civil Aviation Organization [ICAO]
A specialized agency of the United Nations whose objective is to develop the principles and techniques of international air navigation and to foster planning and development of international civil air transport. Regions include: 1. African-Indian Ocean Region 2. Caribbean Region 3. European Region 4. Middle East/Asia Region 5. North American Region 6. North Atlantic Region 7. Pacific Region 8. South American Region
International Flight Information Manual
A publication designed primarily as a pilot’s preflight planning guide for flights into foreign airspace and for flights returning to the U.S. from foreign locations.
International standard atmosphere (IAS)
A model of standard variation of pressure and temperature.
Internet
An electronic network that connects computers around the world.
Interpolate
To determine a value in a series between two known values.
Interpolation
The estimation of an intermediate value of a quantity that falls between marked values in a series. Example: In a measurement of length, with a rule that is marked in eighths of an inch, the value falls between 3/8 inch and 1/2 inch. The estimated (interpolated) value might then be said to be 7/16 inch.
Interrogator
The ground-based surveillance radar beacon transmitter-receiver, which normally scans in synchronism with a primary radar, transmitting discrete radio signals which repetitiously request all transponders on the mode being used to reply. The replies received are mixed with the primary radar returns and displayed on the same plan position indicator (radar scope). Also, applied to the airborne element of the TACAN/DME system.
Intersecting Runways
Two or more runways which cross or meet within their lengths.
Intersection
Typically, the point at which two VOR radial position lines cross on a route, usually intersecting at a good angle for positive indication of position, resulting in a VOR/VOR fix.
Intersection Departure
A departure from any runway intersection except the end of the runway.
Intersection Takeoff
Intersection Departure.
Interstage Turbine Temperature (ITT)
The temperature of the gases between the high pressure and low pressure turbines.
Interstate air commerce
The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation or navigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in any State of the United States, or the District of Columbia, and a place in any other State of the United States, or the District of Columbia; or between places in the same State of the United States through the airspace over any place outside thereof; or between places in the same territory or possession of the United States, or the District of Columbia.
Interstate air transportation
The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft in commerce:
(1) Between a place in a State or the District of Columbia and another place in another State or the District of Columbia;
(2) Between places in the same State through the airspace over any place outside that State; or
(3) Between places in the same possession of the United States;
Whether that commerce moves wholly by aircraft of partly by aircraft and partly by other forms of transportation.
Intertropical convergence zone
The boundary zone between the trade wind system of the Northern and Southern Hemispheres; it is characterized in maritime climates by showery precipitation with cumulonimbus clouds sometimes extending to great heights.
Into A.C
Current of the proper voltage and frequency to operate A.C. gyro instruments.
Intrastate air transportation
The carriage of persons or property as a common carrier for compensation or hire, by turbojet-powered aircraft capable of carrying thirty or more persons, wholly within the same State of the United States.
Invalid Non-Alert
A situation in which the safety logic software did not issue an alert when an alert was required, based upon the design specifications.
Inversion
An increase in temperature with height-a reversal of the normal decrease with height in the troposphere; may also be applied to other meteorological properties.
Inversion illusion
The feeling that the aircraft is tumbling backwards, caused by an abrupt change from climb to straight- and-level flight while in situations lacking visual reference.
Inverter
An electrical device that changes DC to AC power.
ISA (International Standard Atmosphere)
Standard atmospheric conditions consisting of a temperature of 59°F (15°C), and a barometric pressure of 29.92 in. Hg. (1013.2 mb) at sea level. ISA values can be calculated for various altitudes using a standard lapse rate of approximately 2°C per 1,000 feet.
Iso echo
In radar circuitry, a circuit that reverses signal strength above a specified intensity level, thus causing a void on the scope in the most intense portion of an echo when maximum intensity is greater than the specified level.
Isobar
A line of equal or constant barometric pressure.
Isobars
Lines which connect points of equal barometric pressure.
Isogonic lines
Lines drawn across aeronautical charts to connect points having the same magnetic variation.
Isoheight
On a weather chart, a line of equal height; same as contour (1).
Isoline
A line of equal value of a variable quantity, i.e., an isoline of temperature is an isotherm, etc. Isobars (A line of equal or constant barometric pressure.) and isotachs (A line of equal or constant wind speed.) are examples.
Isoshear
A line of equal wind shear.
Isotach
A line of equal or constant wind speed.
Isotherm
A line of equal or constant temperature.
Isothermal
Of equal or constant temperature, with respect to either space or time; more commonly, temperature with height; a zero lapse rate.
Jamming
Electronic or mechanical interference which may disrupt the display of aircraft on radar or the transmission/reception of radio communications/navigation.
Jet Blast
Jet engine exhaust (thrust stream turbulence).
Jet Powered Airplane
An aircraft powered by a turbojet or turbofan engine.
Jet route
A route designated to serve flight operations from 18,000 feet MSL up to and including FL 450.
Jet stream
A high-velocity narrow stream of winds, usually found near the upper limit of the troposphere, which flows generally from west to east.
Jettisoning Of External Stores
Airborne release of external stores; e.g., tiptanks, ordnance.
Joint Use Restricted Area
Restricted Area.
Judgment
The mental process of recognizing and analyzing all pertinent information in a particular situation, a rational evaluation of alternative actions in response to it, and a timely decision on which action to take.
Katabatic wind
Any wind blowing downslope. For example: fall wind, foehn.
Kelvin temperature scale (abbreviated K)
A temperature scale with zero degrees equal to the temperature at which all molecular motion ceases, i.e., absolute zero (0° K = -273° C); the Kelvin degree is identical to the Celsius degree; hence at standard sea level pressure, the melting point is 273° K and the boiling point 373° K.
KIAS
Knots Indicated Airspeed.
Kinesthesia
The sensing of movements by feel.
Kite
A framework, covered with paper, cloth, metal, or other material, intended to be flown at the end of a rope or cable, and having as its only support the force of the wind moving past its surfaces.
Knot
A unit of speed equal to one nautical mile per hour.
Knowledge
Information that humans are consciously aware of and can articulate.
Known Traffic
With respect to ATC clearances, means aircraft whose altitude, position, and intentions are known to ATC.
Known, Observed, or Detected Ice Accretion
Actual ice that is observed visually to be on the aircraft by the flightcrew or identified by onboard sensors.
Kollsman window
A barometric scale window of a sensitive altimeter used to adjust the altitude for the altimeter setting.
Lack of common experience
In communication, a difficulty which arises because words have different meanings for the source and the receiver of information due to their differing backgrounds.
Lag
The delay that occurs before an instrument needle attains a stable indication.
Land And Hold Short Operations
Operations which include simultaneous takeoffs and landings and/or simultaneous landings when a landing aircraft is able and is instructed by the controller to hold-short of the intersecting runway/taxiway or designated hold-short point. Pilots are expected to promptly inform the controller if the hold short clearance cannot be accepted.
Land as soon as possible
ATC instruction to pilot. Land without delay at the nearest suitable area, such as an open field, at which a safe approach and landing is assured.
Land as soon as practical
ATC instruction to pilot. The landing site and duration of flight are at the discretion of the pilot. Extended flight beyond the nearest approved landing area is not recommended.
Land breeze
A coastal breeze blowing from land to sea, caused by temperature difference when the sea surface is warmer than the adjacent land. Therefore, it usually blows at night and alternates with a sea breeze, which blows in the opposite direction by day.
Land immediately
ATC instruction to pilot. The urgency of the landing is paramount. The primary consideration is to ensure the survival of the occupants. Landing in trees, water, or other unsafe areas should be considered only as a last resort.
Land-Based Air Defense Identification Zone
An ADIZ over U.S. metropolitan areas, which is activated and deactivated as needed, with dimensions, activation dates and other relevant information disseminated via NOTAM. Note: ADIZ locations and operating and flight plan requirements for civil aircraft operations are specified in 14 CFR Part 99.
Landing Area
Any locality either on land, water, or structures, including airports/heliports and intermediate landing fields, which is used, or intended to be used, for the landing and takeoff of aircraft whether or not facilities are provided for the shelter, servicing, or for receiving or discharging passengers or cargo.
Landing Area [ICAO]
That part of a movement area intended for the landing or take-off of aircraft.
Landing Direction Indicator
A device which visually indicates the direction in which landings and takeoffs should be made.
Landing Distance Available (LDA)
ICAO defines LDA as the length of runway, which is declared available and suitable for the ground run of an aeroplane landing.
Landing Distance Available [ICAO]
The length of runway which is declared available and suitable for the ground run of an aeroplane landing.
Landing gear extended speed
The maximum speed at which an aircraft can be safely flown with the landing gear extended.
Landing gear operating speed
The maximum speed at which the landing gear can be safely extended or retracted.
Landing Minimums
The minimum visibility prescribed for landing a civil aircraft while using an instrument approach procedure. The minimum applies with other limitations set forth in 14 CFR Part 91 with respect to the Minimum Descent Altitude (MDA) or Decision Height (DH) prescribed in the instrument approach procedures as follows: a. Straight-in landing minimums. A statement of MDA and visibility, or DH and visibility, required for a straight-in landing on a specified runway, or b. Circling minimums. A statement of MDA and visibility required for the circle-to-land maneuver. Note: Descent below the established MDA or DH is not authorized during an approach unless the aircraft is in a position from which a normal approach to the runway of intended landing can be made and adequate visual reference to required visual cues is maintained.
Landing Roll
The distance from the point of touchdown to the point where the aircraft can be brought to a stop or exit the runway.
Landing Sequence
The order in which aircraft are positioned for landing.
Landing Weight
The takeoff weight of an aircraft less the fuel burned and/or dumped en route.
Lapse rate
The rate of decrease of an atmospheric variable with height; commonly refers to decrease of temperature with height.
Large
An Aircraft Class Wake Turbulence Separation Minima. Aircraft of more than 41,000 pounds, maximum certificated takeoff weight, up to but not including 300,000 pounds.
Large aircraft
Aircraft of more than 12,500 pounds, maximum certificated takeoff weight.
Last Assigned Altitude
The last altitude/flight level assigned by ATC and acknowledged by the pilot.
Latent heat
The amount of heat absorbed (converted to kinetic energy) during the processes of change of liquid water to water vapor, ice to water vapor, or ice to liquid water; or the amount released during the reverse processes. Four basic classifications are: latent heat of condensation, latent heat of fusion, latent heat of sublimation, and latent heat of vaporization.
Latent heat of condensation
Heat released during change of water vapor to water.
Latent heat of fusion
Heat released during change of water to ice or the amount absorbed in change of ice to water.
Latent heat of sublimation
Heat released during change of water vapor to ice or the amount absorbed in the change of ice to water vapor.
Latent heat of vaporization
Heat absorbed in the change of water to water vapor; the negative of latent heat of condensation.
Lateral Axis
An imaginary line passing through the center of gravity of an airplane and extending across the airplane from wingtip to wingtip.
Lateral Balance
Balance around the roll, or longitudinal, axis.
Lateral Navigation (LNAV)
Azimuth navigation, without positive vertical guidance. This type of navigation is associated with nonprecision approach procedures or en route.
Lateral Offset Moment
The moment, in lb-in, of a force that tends to rotate a helicopter about its longitudinal axis. The lateral offset moment is the product of the weight of the object and its distance from butt line zero. Lateral offset moments that tend to rotate the aircraft clockwise are positive, and those that tend to rotate it counterclockwise are negative.
Lateral Separation
The lateral spacing of aircraft at the same altitude by requiring operation on different routes or in different geographical locations.
Lateral Stability (Rolling)
The stability about the longitudinal axis of an aircraft. Rolling stability or the ability of an airplane to return to level flight due to a disturbance that causes one of the wings to drop.
Latitude
Measurement north or south of the equator in degrees, minutes, and seconds. Lines of latitude are also referred to as parallels.
Layer
In reference to sky cover, clouds or other obscuring phenomena whose bases are approximately at the same level. The layer may be continuous or composed of detached elements. The term “layer” does not imply that a clear space exists between the layers or that the clouds or obscuring phenomena composing them are of the same type.
Lead radial
The radial at which the turn from the DME arc to the inbound course is started.
Lead-Acid Battery
A commonly used secondary cell having lead as its negative plate and lead peroxide as its positive plate. Sulfuric acid and water serve as the electrolyte.
Lead-off question
In the guided discussion method, a question used by an instructor to open up an area for discussion and get the discussion started.
Leading Edge
The part of an airfoil that meets the airflow first.
Leading Edge Devices
High lift devices which are found on the leading edge of the airfoil. The most common types are fixed slots, movable slats, and leading edge flaps.
Leading Edge Flap
A portion of the leading edge of an airplane wing that folds downward to increase the camber, lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount of aerodynamic lift that is produced at any given airspeed.
Leading-edge flap
A portion of the leading edge of an airplane wing that folds downward to increase the camber, lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount of aerodynamic lift that is produced at any given airspeed.
Lean of Peak
A mixture setting where the mixture was leaned from the full-rich fuel flow position to lean of peak exhaust gas temperature (EGT).
Leans, the
A physical sensation caused by an abrupt correction of a banked attitude entered too slowly to stimulate the motion sensing system in the inner ear. The abrupt correction can create the illusion of banking in the opposite direction.
Learning
A change in behavior as a result of experience.
Learning plateau
A learning phenomenon where progress appears to cease or slow down for a significant period of time before once again increasing.
Learning style
Preferred way(s) by which people learn. Common learning styles include visual, auditory, and kinesthetic, or tactile (hands on). Learning skills can be loosely grouped into physical and cognitive styles.
Learning theory
A body of principles advocated by psychologists and educators to explain how people acquire skills, knowledge, and attitudes.
Lecture method
An educational presentation usually delivered by an instructor to a group of students with the use of instructional aids and training devices. Lectures are useful for the presentation of new material, summarizing ideas, and showing relationships between theory and practice.
Lee wave
Any stationary wave disturbance caused by a barrier in a fluid flow. In the atmosphere when sufficient moisture is present, this wave will be evidenced by lenticular clouds to the lee of mountain barriers; also called mountain wave or standing wave.
Left Base Area
A type of Terminal Arrival Area. A 30NM arc centered on the right corner IAF (Initial Approach Fix). The area shares a boundary with the straight-in area except that it extends out for 30NM from the IAF and is bounded on the other side by a line extending from the IF through the FAF to the arc.
Lenticular cloud (or lenticularis)
A species of cloud whose elements have the form of more or less isolated, generally smooth lenses or almonds. These clouds appear most often in formations of orographic origin, the result of lee waves, in which case they remain nearly stationary with respect to the terrain (standing cloud), but they also occur in regions without marked orography.
Lesson plan
An organized outline for a single instructional period. It is a necessary guide for the instructor in that it tells what to do, in what order to do it, and what procedure to use in teaching the material of a lesson.
Level of free convection (abbreviated LFC)
The level at which a parcel of air lifted dry-adiabatically until saturated and moist-adiabatically thereafter would become warmer than its surroundings in a conditionally unstable atmosphere.
Licensed Empty Weight
The empty weight that consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment as specified in the equipment list. Some manufacturers used this term prior to GAMA standardization.
Lift
One of the four main forces acting on an aircraft. On a fixed-wing aircraft, an upward force created by the effect of airflow as it passes over and under the wing.
Lift Coefficient
A coefficient representing the lift of a given airfoil. Lift coefficient is obtained by dividing the lift by the free-stream dynamic pressure and the representative area under consideration.
Lift-Off
The act of becoming airborne as a result of the wings lifting the airplane off the ground, or the pilot rotating the nose up, increasing the angle of attack to start a climb.
Lift/Drag Ratio
The efficiency of an airfoil section. It is the ratio of the coefficient of lift to the coefficient of drag for any given angle of attack.
Lifting condensation level (abbreviated LCL)
The level at which a parcel of unsaturated air lifted dry-adiabatically would become saturated. Compare level of free convection and convective condensation level.
Light Gun
A handheld directional light signaling device which emits a brilliant narrow beam of white, green, or red light as selected by the tower controller. The color and type of light transmitted can be used to approve or disapprove anticipated pilot actions where radio communication is not available. The light gun is used for controlling traffic operating in the vicinity of the airport and on the airport movement area.
Light Icing
The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used.
Light-sport aircraft
An aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:
(1) A maximum takeoff weight of not more than—
(i) 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or
(ii) 1,430 pounds (650 kilograms) for an aircraft intended for operation on water.
(2) A maximum airspeed in level flight with maximum continuous power (Vh) of not more than 120 knots CAS under standard atmospheric conditions at sea level.
(3) A maximum never-exceed speed (Vne) of not more than 120 knots CAS for a glider.
(4) A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (Vs1) of not more than 45 knots CAS at the aircraft’s maximum certificated takeoff weight and most critical center of gravity.
(5) A maximum seating capacity of no more than two persons, including the pilot.
(6) A single, reciprocating engine, if powered.
(7) A fixed or ground-adjustable propeller if a powered aircraft other than a powered glider.
(8) A fixed or feathering propeller system if a powered glider.
(9) A fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.
(10) A non-pressurized cabin, if equipped with a cabin.
(11) Fixed landing gear, except for an aircraft intended for operation on water or a glider.
(12) Fixed or retractable landing gear, or a hull, for an aircraft intended for operation on water.
(13) Fixed or retractable landing gear for a glider.
Lighted Airport
An airport where runway and obstruction lighting is available.
Lighter-than-air aircraft
Aircraft that can rise and remain suspended by using contained gas weighing less than the air that is displaced by the gas.
Lightning
Generally, any and all forms of visible electrical discharge produced by a thunderstorm.
Limit Load Factor
Amount of stress, or load factor, that an aircraft can withstand before structural damage or failure occurs.
Line Up And Wait (LUAW)
Used by ATC to inform a pilot to taxi onto the departure runway to line up and wait. It is not authorization for takeoff. It is used when takeoff clearance cannot immediately be issued because of traffic or other reasons.
Lines of flux
Invisible lines of magnetic force passing between the poles of a magnet.
Link
On a website, an external web location that can be accessed by merely clicking on words identifying the new site. They are usually identified by a different color type, underlining, or a button (picture or icon) indicating access to a new site.
Liquid Water Content (LWC)
The total mass of water in all the liquid cloud drops within a unit volume of cloud. LWC is usually discussed in terms of grams of water per cubic meter of air (g/m3).
Lithometeor
The general term for dry particles suspended in the atmosphere such as dust, haze, smoke, and sand.
Load Cell
A component in an electronic weighing system that is placed between the jack and the jack pad on the aircraft. The load cell contains strain gauges whose resistance changes with the weight on the cell.
Load Factor
The ratio of the load supported by the airplane’s wings to the actual weight of the aircraft and its contents. Also referred to as G-loading.
Loading Graph
A graph of load weight and load moment indexes. Diagonal lines for each item relate the weight to the moment index without having to use mathematics.
Loading Schedule
A method for calculating and documenting aircraft weight and balance prior to taxiing, to ensure the aircraft will remain within all required weight and balance limitations throughout the flight.
Loadmeter
A type of ammeter installed between the generator output and the main bus in an aircraft electrical system.
Local Airport Advisory (LAA)
A service provided by facilities, which are located on the landing airport, have a discrete ground-to-air communication frequency or the tower frequency when the tower is closed, automated weather reporting with voice broadcasting, and a continuous ASOS/AWSS/AWOS data display, other continuous direct reading instruments, or manual observations available to the specialist.
Local Area Augmentation System (LAAS)
LAAS further increases the accuracy of GPS and improves signal integrity warnings.
Local Traffic
Aircraft operating in the traffic pattern or within sight of the tower, or aircraft known to be departing or arriving from flight in local practice areas, or aircraft executing practice instrument approaches at the airport.
Localizer
The component of an ILS which provides course guidance to the runway.
Localizer (LOC)
The portion of an ILS that gives left/right guidance information down the centerline of the instrument runway for final approach.
Localizer Course [ICAO]
The locus of points, in any given horizontal plane, at which the DDM (difference in depth of modulation) is zero.
Localizer Offset
An angular offset of the localizer from the runway extended centerline in a direction away from the no transgression zone (NTZ) that increases the normal operating zone (NOZ) width. An offset requires a 50 foot increase in DH and is not authorized for CAT II and CAT III approaches.
Localizer Performance with Vertical Guidance (LPV)
LPV is one of the four lines of approach minimums found on an RNAV (GPS) approach chart. Lateral guidance accuracy is equivalent to a localizer. The HAT is published as a DA since it uses an electronic glide path that is not dependent on any ground equipment or barometric aiding and may be as low as 200 feet and 1/2 SM visibility depending on the airport terrain and infrastructure. WAAS avionics approved for LPV is required. Baro-VNAV is not authorized to fly the LPV line of minimums on a RNAV (GPS) procedure since it uses an internally generated descent path that is subject to cold temperature effects and incorrect altimeter settings.
Localizer Type Directional Aid
A NAVAID used for nonprecision instrument approaches with utility and accuracy comparable to a localizer but which is not a part of a complete ILS and is not aligned with the runway.
Localizer Usable Distance
The maximum distance from the localizer transmitter at a specified altitude, as verified by flight inspection, at which reliable course information is continuously received.
Localizer-type directional aid (LDA)
A NAVAID used for nonprecision instrument approaches with utility and accuracy comparable to a localizer but which is not a part of a complete ILS and is not aligned with the runway. Some LDAs are equipped with a glide slope.
Locator middle marker (LMM)
Nondirectional radio beacon (NDB) compass locator, collocated with a middle marker (MM).
Locator outer marker (LOM)
NDB compass locator, collocated with an outer marker (OM).
Locator [ICAO]
An LM/MF NDB used as an aid to final approach. Note: A locator usually has an average radius of rated coverage of between 18.5 and 46.3 km (10 and 25 NM).
Long Range Navigation
LORAN. [Decommissioned in 2010]
Long range navigation (LORAN)
[Decommissioned in 2010] An electronic navigational system by which hyperbolic lines of position are determined by measuring the difference in the time of reception of synchronized pulse signals from two fixed transmitters. LORAN A operates in the 1750 to 1950 kHz frequency band. LORAN C and D operate in the 100 to 110 kHz frequency band.
Long-range communication system (LRCS)
A system that uses satellite relay, data link, high frequency, or another approved communication system which extends beyond line of sight.
Long-range navigation system (LRNS)
An electronic navigation unit that is approved for use under instrument flight rules as a primary means of navigation, and has at least one source of navigational input, such as inertial navigation system, global positioning system, Omega/very low frequency, or Loran C.
Long-term memory
The portion of the brain that stores information that has been determined to be of sufficient value to be retained. In order for it to be retained in longterm memory, it must have been processed or coded in the working memory.
Longitude
Measurement east or west of the Prime Meridian in degrees, minutes, and seconds. The Prime Meridian is 0° longitude and runs through Greenwich, England. Lines of longitude are also referred to as meridians.
Longitudinal Axis
An imaginary line through an aircraft from nose to tail, passing through its center of gravity. The longitudinal axis is also called the roll axis of the aircraft. Movement of the ailerons rotates an airplane about its longitudinal axis.
Longitudinal Balance
Balance around the pitch, or lateral, axis.
Longitudinal Separation
The longitudinal spacing of aircraft at the same altitude by a minimum distance expressed in units of time or miles.
Longitudinal Stability (Pitching)
Stability about the lateral axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.
LORAN
[Decommissioned in 2010] An electronic navigational system by which hyperbolic lines of position are determined by measuring the difference in the time of reception of synchronized pulse signals from two fixed transmitters. Loran A operates in the 1750-1950 kHz frequency band. Loran C and D operate in the 100-110 kHz frequency band.
LORAN-C
[Decommissioned in 2010] A radio navigation system that utilizes master and slave stations transmitting timed pulses. The time difference in reception of pulses from several stations establishes a hyperbolic line of position, which can be identified on a LORAN chart. A fix in position is obtained by utilizing signals from two or more stations.
Loss of Separation
An occurrence or operation that results in less than prescribed separation between aircraft, or between an aircraft and a vehicle, pedestrian, or object.
Lost Communications
Loss of the ability to communicate by radio. Aircraft are sometimes referred to as NORDO (No Radio). Standard pilot procedures are specified in 14 CFR Part 91. Radar controllers issue procedures for pilots to follow in the event of lost communications during a radar approach when weather reports indicate that an aircraft will likely encounter IFR weather conditions during the approach.
Low
An area of low barometric pressure, with its attendant system of winds. Also called a barometric depression or cyclone.
Low Altitude Airway Structure
The network of airways serving aircraft operations up to but not including 18,000 feet MSL.
Low Altitude Alert System
An automated function of the TPX-42 that alerts the controller when a Mode C transponder equipped aircraft on an IFR flight plan is below a predetermined minimum safe altitude. If requested by the pilot, Low Altitude Alert System monitoring is also available to VFR Mode C transponder equipped aircraft.
Low Altitude Alert, Check Your Altitude Immediately
Safety Alert.
Low Approach
An approach over an airport or runway following an instrument approach or a VFR approach including the go-around maneuver where the pilot intentionally does not make contact with the runway.
Low Frequency
The frequency band between 30 and 300 kHz.
Low Level Autorotation
Commences at an altitude well below the traffic pattern, usually below 100 feet AGL and is used primarily for tactical military training.
Low or medium frequency
A frequency range between 190-535 kHz with the medium frequency above 300 kHz. Generally associated with nondirectional beacons transmitting a continuous carrier with either a 400 or 1,020 Hz modulation.
Lubber line
The reference line used in a magnetic compass or heading indicator.
Lubberline
The reference line used in a magnetic compass or heading indicator.
Mach
Speed relative to the speed of sound. Mach 1 is the speed of sound.
Mach Buffet
Airflow separation behind a shock-wave pressure barrier caused by airflow over flight surfaces exceeding the speed of sound.
Mach Compensating Device
A device to alert the pilot of inadvertent excursions beyond its certified maximum operating speed.
Mach Critical
The MACH speed at which some portion of the airflow over the wing first equals MACH 1.0. This is also the speed at which a shock wave first appears on the airplane.
Mach meter
The instrument that displays the ratio of the speed of sound to the true airspeed an aircraft is flying.
Mach number
The ratio of the true airspeed of the aircraft to the speed of sound in the same atmospheric conditions, named in honor of Ernst Mach, late 19th century physicist.
Mach Technique [ICAO]
Describes a control technique used by air traffic control whereby turbojet aircraft operating successively along suitable routes are cleared to maintain appropriate MACH numbers for a relevant portion of the en route phase of flight. The principle objective is to achieve improved utilization of the airspace and to ensure that separation between successive aircraft does not decrease below the established minima.
Mach Tuck
A condition that can occur when operating a swept-wing airplane in the transonic speed range. A shock wave could form in the root portion of the wing and cause the air behind it to separate. This shock-induced separation causes the center of pressure to move aft. This, combined with the increasing amount of nose down force at higher speeds to maintain level flight, causes the nose to “tuck.” If not corrected, the airplane could enter a steep, sometimes unrecoverable dive.
Magnetic bearing (MB)
The direction to or from a radio transmitting station measured relative to magnetic north.
Magnetic Compass
A device for determining direction measured from magnetic north.
Magnetic Course
A predetermined desired course direction to be followed (measured in degrees from local magnetic north).
Magnetic dip
A vertical attraction between a compass needle and the magnetic poles. The closer the aircraft is to a pole, the more severe the effect.
Magnetic heading (MH)
The direction an aircraft is pointed with respect to magnetic north.
Magnetic Variation
The difference in degrees between the measured values of true north and magnetic north at that location.
Magneto
A self-contained, engine-driven unit that supplies electrical current to the spark plugs; completely independent of the airplane’s electrical system. Normally there are two magnetos per engine.
Magnus effect
Lifting force produced when a rotating cylinder produces a pressure differential. This is the same effect that makes a baseball curve or a golf ball slice.
Main Gear
The wheels of an aircraft’s landing gear that supports the major part of the aircraft’s weight.
Main rotor
The rotor that supplies the principal lift to a rotorcraft.
Maintain
A. Concerning altitude/flight level, the term means to remain at the altitude/flight level specified. The phrase “climb and” or “descend and” normally precedes “maintain” and the altitude assignment; e.g., “descend and maintain 5,000.”
B. Concerning other ATC instructions, the term is used in its literal sense; e.g., maintain VFR.
Maintenance
Inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.
Maintenance Planning Friction Level
The friction level specified in AC 150/5320-12, Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces, which represents the friction value below which the runway pavement surface remains acceptable for any category or class of aircraft operations but which is beginning to show signs of deterioration. This value will vary depending on the particular friction measurement equipment used.
Major alteration
An alteration not listed in the aircraft, aircraft engine, or propeller specifications—
(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
(2) That is not done according to accepted practices or cannot be done by elementary operations.
Major repair
A repair:
(1) That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
(2) That is not done according to accepted practices or cannot be done by elementary operations.
Make Short Approach
Used by ATC to inform a pilot to alter his/her traffic pattern so as to make a short final approach.
Mammato cumulus
Obsolete. Now referred to as cumulonimbus mamma.
Man Portable Air Defense Systems (MANPADS)
MANPADS are lightweight, shoulder-launched, missile systems used to bring down aircraft and create mass casualties. The potential for MANPADS use against airborne aircraft is real and requires familiarity with the subject. Terrorists choose MANPADS because the weapons are low cost, highly mobile, require minimal set-up time, and are easy to use and maintain. Although the weapons have limited range, and their accuracy is affected by poor visibility and adverse weather, they can be fired from anywhere on land or from boats where there is unrestricted visibility to the target.
Mandatory altitude
An altitude depicted on an instrument approach chart with the altitude value both underscored and overscored. Aircraft are required to maintain altitude at the depicted value.
Mandatory block altitude
An altitude depicted on an instrument approach chart with two underscored and overscored altitude values between which aircraft are required to maintain altitude.
Maneuverability
Ability of an aircraft to change directions along a flightpath and withstand the stresses imposed upon it.
Maneuvering Speed (Va)
The maximum speed where full, abrupt control movement can be used without overstressing the airframe.
Manifold absolute pressure
The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury.
Manifold pressure
Absolute pressure as measured at the appropriate point in the induction system and usually expressed in inches of mercury.
Manifold Pressure (MP)
The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury.
Mare’s tail
Irregularly curved wisps of cirriform clouds.
Margin identification
The top and bottom areas on an instrument approach chart that depict information about the procedure, including airport location and procedure identification.
Maritime polar air (abbreviated mP)
Also called polar air. An air mass with characteristics developed over high latitudes, especially within the subpolar highs. Maritime polar (mP) initially possesses similar properties to those of continental polar air, but in passing over warmer water it becomes unstable with a higher moisture content.
Maritime tropical air (abbreviated mT)
Also called tropical air. An air mass with characteristics developed over low latitudes. Maritime tropical air (mT), the principal type, is produced over the tropical and subtropical seas; very warm and humid.
Marker beacon
A low-powered transmitter that directs its signal upward in a small, fan-shaped pattern. Used along the flight path when approaching an airport for landing, marker beacons indicate both aurally and visually when the aircraft is directly over the facility.
Mass
The amount of matter in a body.
Matching-type test item
A test item in which the student is asked to match alternatives on one list to related alternatives on a second list. The lists may include words, terms, illustrations, phrases, or sentences.
Maximum Allowable Takeoff Power
The maximum power an engine is allowed to develop for a limited period of time; usually about one minute.
Maximum altitude
An altitude depicted on an instrument approach chart with overscored altitude value at which or below aircraft are required to maintain altitude.
Maximum Authorized Altitude
A published altitude representing the maximum usable altitude or flight level for an airspace structure or route segment. It is the highest altitude on a Federal airway, jet route, area navigation low or high route, or other direct route for which an MEA is designated in 14 CFR Part 95 at which adequate reception of navigation aid signals is assured.
Maximum Authorized Altitude (MAA)
An MAA is a published altitude representing the maximum usable altitude or flight level for an airspace structure or route segment. It is the highest altitude on a Federal airway, jet route, RNAV low or high route, or other direct route for which an MEA is designated at which adequate reception of navigation signals is assured.
Maximum engine overtorque
As it applies to turbopropeller and turboshaft engines incorporating free power turbines for all ratings except one engine inoperative (OEI) ratings of two minutes or less, the maximum torque of the free power turbine rotor assembly, the inadvertent occurrence of which, for periods of up to 20 seconds, will not require rejection of the engine from service, or any maintenance action other than to correct the cause. Maximum speed for stability characteristics, V FC/MFC means a speed that may not be less than a speed midway between maximum operating limit speed (VMO/MMO) and demonstrated flight diving speed (VDF/MDF), except that, for altitudes where the Mach number is the limiting factor, MFC need not exceed the Mach number at which effective speed warning occurs.
Maximum Landing Weight
The greatest weight that an airplane normally is allowed to have at landing.
Maximum Permissible Hoist Load
The maximum external load that is permitted for a helicopter to carry. This load is specified in the POH.
Maximum Ramp Weight
The total weight of a loaded aircraft, including all fuel. It is greater than the takeoff weight due to the fuel that will be burned during the taxi and runup operations. Ramp weight may also be referred to as taxi weight.
Maximum Takeoff Weight
The maximum allowable weight for takeoff.
Maximum Taxi Weight
Maximum weight approved for ground maneuvers. This is the same as maximum ramp weight.
Maximum Weight
The maximum authorized weight of the aircraft and all of its equipment as specified in the Type Certificate Data Sheets (TCDS) for the aircraft.
Maximum wind axis
On a constant pressure chart, a line denoting the axis of maximum wind speeds at that constant pressure surface.
Maximum Zero Fuel Weight
The maximum authorized weight of an aircraft without fuel. This is the total weight for a particular flight less the fuel. It includes the aircraft and everything that will be carried on the flight except the weight of the fuel.
Maximum Zero Fuel Weight (GAMA)
The maximum weight, exclusive of usable fuel.
Mayday
The international radiotelephony distress signal. When repeated three times, it indicates imminent and grave danger and that immediate assistance is requested.
Mean aerodynamic chord (MAC)
The average distance from the leading edge to the trailing edge of the wing.
Mean sea level
The average height of the surface of the sea at a particular location for all stages of the tide over a 19-year period.
Measured ceiling
A ceiling classification applied when the ceiling value has been determined by instruments or the known heights of unobscured portions of objects, other than natural landmarks.
Median Volume Diameter (MVD)
The diameter such that half the liquid water in a region of cloud is contained in drops of a smaller diameter, and half in drops of a larger diameter.
Medical certificate
Acceptable evidence of physical fitness on a form prescribed by the Administrator.
Melting
The change of ice to liquid water.
Memory
The ability of people and other organisms to encode (initial perception and registration of information), store (retention of encoded information over time), and retrieve (processes involved in using stored information) information.
Mercurial barometer
A barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.
Meridians
Lines of longitude.
Mesophere
A layer of the atmosphere directly above the stratosphere.
Meteorological Impact Statement
An unscheduled planning forecast describing conditions expected to begin within 4 to 12 hours which may impact the flow of air traffic in a specific center’s (ARTCC) area.
Meteorological visibility
In U.S. observing practice, a main category of visibility which includes the subcategories of prevailing visibility and runway visibility. Meteorological visibility is a measure of horizontal visibility near the earth’s surface, based on sighting of objects in the daytime or unfocused lights of moderate intensity at night. Compare slant visibility, runway visual range, vertical visibility. Examples are surface visibility, tower visibility, and sector visibility.
Meteorology
The science of the atmosphere.
Meter Fix Arc
A semicircle, equidistant from a meter fix, usually in low altitude relatively close to the meter fix, used to help CTAS/HOST calculate a meter time, and determine appropriate sector meter list assignments for aircraft not on an established arrival route or assigned a meter fix.
Meter Fix Time/Slot Time
A calculated time to depart the meter fix in order to cross the vertex at the ACLT. This time reflects descent speed adjustment and any applicable time that must be absorbed prior to crossing the meter fix.
Meter List
Arrival Sector Advisory List.
Meter List Display Interval
A dynamic parameter which controls the number of minutes prior to the flight plan calculated time of arrival at the meter fix for each aircraft, at which time the TCLT is frozen and becomes an ACLT; i.e., the VTA is updated and consequently the TCLT modified as appropriate until frozen at which time updating is suspended and an ACLT is assigned. When frozen, the flight entry is inserted into the arrival sector’s meter list for display on the sector PVD/MDM. MLDI is used if filed true airspeed is less than or equal to freeze speed parameters (FSPD).
Metering
A method of time-regulating arrival traffic flow into a terminal area so as not to exceed a predetermined terminal acceptance rate.
Metering Airports
Airports adapted for metering and for which optimum flight paths are defined. A maximum of 15 airports may be adapted.
Metering Fix
A fix along an established route over which aircraft will be metered prior to entering terminal airspace. Normally, this fix should be established at a distance from the airport which will facilitate a profile descent 10,000 feet above airport elevation (AAE) or above.
Metering Position List
An ordered list of data on arrivals for a selected metering airport displayed on a metering position PVD/MDM.
Metering Position(S)
Adapted PVDs/MDMs and associated “D” positions eligible for display of a metering position list. A maximum of four PVDs/MDMs may be adapted.
METO Horsepower (maximum except takeoff)
The maximum power allowed to be continuously produced by an engine. Takeoff power is usually limited to a given amount of time, such as 1 minute or 5 minutes.
Micro-En Route Automated Radar Tracking System (MEARTS)
An automated radar and radar beacon tracking system capable of employing both short-range (ASR) and long-range (ARSR) radars. This microcomputer driven system provides improved tracking, continuous data recording, and use of full digital radar displays.
Microbarograph
An aneroid barograph designed to record atmospheric pressure changes of very small magnitudes.
Microburst
A strong downdraft which normally occurs over horizontal distances of 1 NM or less and vertical distances of less than 1,000 feet. In spite of its small horizontal scale, an intense microburst could induce windspeeds greater than 100 knots and downdrafts as strong as 6,000 feet per minute.
Microwave Landing System
A precision instrument approach system operating in the microwave spectrum which normally consists of the following components: a. Azimuth Station. b. Elevation Station. c. Precision Distance Measuring Equipment.
Microwave landing system (MLS)
A precision instrument approach system operating in the microwave spectrum which normally consists of an azimuth station, elevation station, and precision distance measuring equipment.
Middle Compass Locator (LMM)
A compass locator installed at the site of the middle marker of an instrument landing system.
Middle Marker
A marker beacon that defines a point along the glideslope of an ILS normally located at or near the point of decision height (ILS Category I). It is keyed to transmit alternate dots and dashes, with the alternate dots and dashes keyed at the rate of 95 dot/dash combinations per minute on a 1300 Hz tone, which is received aurally and visually by compatible airborne equipment.
Mileage Break
A point on a route where the leg segment mileage ends, and a new leg segment mileage begins, often at a route turning point.
Mileage breakdown
A fix indicating a course change that appears on the chart as an x at a break between two segments of a federal airway.
Miles-In-Trail
A specified distance between aircraft, normally, in the same stratum associated with the same destination or route of flight.
Military Airspace Management System (MAMS)
A Department of Defense system to collect and disseminate information on the current status of special use airspace. This information is provided to the Special Use Airspace Management System (SAMS). The electronic interface also provides SUA schedules and historical activation and utilization data.
Military Authority Assumes Responsibility For Separation
A condition whereby the military services involved assume responsibility for separation between participating military aircraft in the ATC system. It is used only for required IFR operations which are specified in letters of agreement or other appropriate FAA or military documents.
Military Landing Zone
A landing strip used exclusively by the military for training. A military landing zone does not carry a runway designation.
Military operations area
A military operations area (MOA) is airspace established outside Class A airspace to separate or segregate certain nonhazardous military activities from IFR Traffic and to identify for VFR traffic where theses activities are conducted.
Military operations area (MOA)
Airspace established for the purpose of separating certain military training activities from IFR traffic.
Military training route (MTR)
Airspace of defined vertical and lateral dimensions established for the conduct of military training at airspeeds in excess of 250 knots indicated airspeed (KIAS).
Military Training Routes
Airspace of defined vertical and lateral dimensions established for the conduct of military flight training at airspeeds in excess of 250 knots IAS.
Millibar (abbreviated mb.)
An internationally used unit of pressure equal to 1,000 dynes per square centimeter. It is convenient for reporting atmospheric pressure.
Minima
Minimums.
Minimum altitude
An altitude depicted on an instrument approach chart with the altitude value underscored. Aircraft are required to maintain altitude at or above the depicted value.
Minimum Controllable Airspeed
An airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall.
Minimum Crossing Altitude
The lowest altitude at certain fixes at which an aircraft must cross when proceeding in the direction of a higher minimum en route IFR altitude (MEA).
Minimum Crossing Altitude (MCA)
An MCA is the lowest altitude at certain fixes at which the aircraft must cross when proceeding in the direction of a higher minimum en route IFR altitude. MCAs are established in all cases where obstacles intervene to prevent pilots from maintaining obstacle clearance during a normal climb to a higher MEA after passing a point beyond which the higher MEA applies.
Minimum Descent Altitude
The lowest altitude, expressed in feet above mean sea level, to which descent is authorized on final approach or during circle-to-land maneuvering in execution of a standard instrument approach procedure where no electronic glideslope is provided.
Minimum Descent Altitude (MDA)
The lowest altitude, expressed in feet above mean sea level, to which descent is authorized on final approach or during circle-to-land maneuvering in execution of a standard instrument approach procedure where no electronic glide slope is provided.
Minimum drag
The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag is minimized.
Minimum Drag Speed (L/Dmax)
The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag is minimized.
Minimum En Route Altitude (MEA)
The MEA is the lowest published altitude between radio fixes that assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes. The MEA prescribed for a Federal airway or segment, RNAV low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route.
Minimum En Route IFR Altitude (MEA)
The lowest published altitude between radio fixes which assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes. The MEA prescribed for a Federal airway or segment thereof, area navigation low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route.
Minimum equipment list (MEL)
A list developed for larger aircraft that outlines equipment that can be inoperative for various types of flight including IFR and icing conditions. This list is based on the master minimum equipment list (MMEL) developed by the FAA and must be approved by the FAA for use. It is specific to an individual aircraft make and model.
Minimum Friction Level
The friction level specified in AC 150/5320-12, Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces, that represents the minimum recommended wet pavement surface friction value for any turbojet aircraft engaged in LAHSO. This value will vary with the particular friction measurement equipment used.
Minimum Fuel
The amount of fuel necessary for one- half hour of operation at the rated maximum-continuous power setting of the engine, which, for weight and balance purposes, is 1/12 gallon per maximum-except-takeoff (METO) horse-power. It is the maximum amount of fuel that could be used in weight and balance computations when low fuel might adversely affect the most critical balance conditions. To determine the weight of the minimum fuel in pounds, divide the METO horsepower by two.
Minimum Holding Altitude
The lowest altitude prescribed for a holding pattern which assures navigational signal coverage, communications, and meets obstacle clearance requirements.
Minimum IFR Altitude (MIA)
Minimum altitudes for IFR operations are prescribed in Part 91. These MIAs are published on NACO charts and prescribed in Part 95 for airways and routes, and in Part 97 for standard instrument approach procedures.
Minimum IFR Altitudes (MIA)
Minimum altitudes for IFR operations as prescribed in 14 CFR Part 91. These altitudes are published on aeronautical charts and prescribed in 14 CFR Part 95 for airways and routes, and in 14 CFR Part 97 for standard instrument approach procedures. If no applicable minimum altitude is prescribed in 14 CFR Part 95 or 14 CFR Part 97, the following minimum IFR altitude applies: a. In designated mountainous areas, 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or b. Other than mountainous areas, 1,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or c. As otherwise authorized by the Administrator or assigned by ATC.
Minimum Navigation Performance Specification
A set of standards which require aircraft to have a minimum navigation performance capability in order to operate in MNPS designated airspace. In addition, aircraft must be certified by their State of Registry for MNPS operation.
Minimum Navigation Performance Specification Airspace
Designated airspace in which MNPS procedures are applied between MNPS certified and equipped aircraft. Under certain conditions, non-MNPS aircraft can operate in MNPSA. However, standard oceanic separation minima is provided between the non-MNPS aircraft and other traffic. Currently, the only designated MNPSA is described as follows: a. Between FL 285 and FL 420; b. Between latitudes 27°N and the North Pole; c. In the east, the eastern boundaries of the CTAs Santa Maria Oceanic, Shanwick Oceanic, and Reykjavik; d. In the west, the western boundaries of CTAs Reykjavik and Gander Oceanic and New York Oceanic excluding the area west of 60°W and south of 38°30’N.
Minimum Navigation Performance Specifications (MNPS)
A set of standards which require aircraft to have a minimum navigation performance capability in order to operate in MNPS designated airspace. In addition, aircraft must be certified by their State of Registry for MNPS operation. Under certain conditions, non-MNPS aircraft can operate in MNPS airspace, however, standard oceanic separation minima is provided between the non-MNPS aircraft and other traffic.
Minimum Obstruction Clearance Altitude (MOCA)
The MOCA is the lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments that meets obstacle clearance requirements for the entire route segment. This altitude also assures acceptable navigational signal coverage only within 22 NM of a VOR.
Minimum Reception Altitude
The lowest altitude at which an intersection can be determined.
Minimum Reception Altitude (MRA)
An MRA is determined by FAA flight inspection traversing an entire route of flight to establish the minimum altitude the navigation signal can be received for the route and for off-course NAVAID facilities that determine a fix. When the MRA at the fix is higher than the MEA, an MRA is established for the fix, and is the lowest altitude at which an intersection can be determined.
Minimum Safe Altitude
A. The minimum altitude specified in 14 CFR Part 91 for various aircraft operations.
B. Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance for emergency use within a specified distance from the navigation facility upon which a procedure is predicated. These altitudes will be identified as Minimum Sector Altitudes or Emergency Safe Altitudes and are established as follows: Minimum Sector Altitudes, Emergency Safe Altitudes.
Minimum safe altitude (MSA)
The minimum altitude depicted on approach charts which provides at least 1,000 feet of obstacle clearance for emergency use within a specified distance from the listed navigation facility.
Minimum Safe Altitude Warning
A function of the ARTS III computer that aids the controller by alerting him/her when a tracked Mode C equipped aircraft is below or is predicted by the computer to go below a predetermined minimum safe altitude.
Minimum Safe Altitudes (MSA)
MSAs are published for emergency use on IAP charts. For conventional navigation systems, the MSA is normally based on the primary omnidirectional facility on which the IAP is predicated. For RNAV approaches, the MSA is based on the runway waypoint (RWY WP) for straight in approaches, or the airport waypoint (APT WP) for circling approaches. For GPS approaches, the MSA center will be the Missed Approach Waypoint (MAWP).
Minimum Sector Altitude [ICAO]
The lowest altitude which may be used under emergency conditions which will provide a minimum clearance of 300 m (1,000 feet) above all obstacles located in an area contained within a sector of a circle of 46 km (25 NM) radius centered on a radio aid to navigation.
Minimum Sector Altitudes
Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance within a 25-mile radius of the navigation facility upon which the procedure is predicated. Sectors depicted on approach charts must be at least 90 degrees in scope. These altitudes are for emergency use only and do not necessarily assure acceptable navigational signal coverage.
Minimum Vectoring Altitude (MVA)
Minimum vectoring altitude charts are developed for areas where there are numerous minimum vectoring altitudes due to variable terrain features or man-made obstacles. MVAs are established for use by ATC when radar ATC is exercised.
Minimums
Weather condition requirements established for a particular operation or type of operation; e.g., IFR takeoff or landing, alternate airport for IFR flight plans, VFR flight, etc.
Minimums section
The area on an IAP chart that displays the lowest altitude and visibility requirements for the approach.
Minor alteration
An alteration other than a major alteration.
Minor repair
A repair other than a major repair.
Minutes-In-Trail
A specified interval between aircraft expressed in time. This method would more likely be utilized regardless of altitude.
Missed approach
A maneuver conducted by a pilot when an instrument approach cannot be completed to a landing.
Missed Approach Holding Waypoint (MAHWP)
An approach waypoint sequenced during the holding portion of the missed approach procedure that is usually a fly-over waypoint, rather than a fly-by waypoint.
Missed Approach Point
A point prescribed in each instrument approach procedure at which a missed approach procedure shall be executed if the required visual reference does not exist.
Missed approach point (MAP)
A point prescribed in each instrument approach at which a missed approach procedure shall be executed if the required visual reference has not been established.
Missed Approach Procedure [ICAO]
The procedure to be followed if the approach cannot be continued.
Missed Approach Segment
Segments Of An Instrument Approach Procedure.
Missed Approach Waypoint (MAWP)
An approach waypoint sequenced during the missed approach procedure that is usually a fly-over waypoint, rather than a fly-by waypoint.
Mist
A popular expression for drizzle or heavy fog.
Mixed
A mixture of clear ice and rime ice.
Mixed ice
A mixture of clear ice and rime ice.
Mixed Ice.
Simultaneous appearance of rime and clear ice or an ice formation that has the characteristics of both rime and clear ice.
Mixing ratio
The ratio by weight of the amount of water vapor in a volume of air to the amount of dry air; usually expressed as grams per kilogram (g/kg).
Mixture
The ratio of fuel to air entering the engine’s cylinders.
MLS Categories
A. MLS Category I. An MLS approach procedure which provides for an approach to a height above touchdown of not less than 200 feet and a runway visual range of not less than 1,800 feet.
B. MLS Category II. Undefined until data gathering/analysis completion.
C. MLS Category III. Undefined until data gathering/analysis completion.
Mock-up
A three-dimensional working model used in which the actual object is either unavailable or too expensive to use. Mock-ups may emphasize some elements while eliminating nonessential elements.
Mode
The letter or number assigned to a specific pulse spacing of radio signals transmitted or received by ground interrogator or airborne transponder components of the Air Traffic Control Radar Beacon System (ATCRBS). Mode A (military Mode 3) and Mode C (altitude reporting) are used in air traffic control.
Mode (SSR Mode) [ICAO]
The letter or number assigned to a specific pulse spacing of the interrogation signals transmitted by an interrogator. There are 4 modes, A, B, C and D specified in Annex 10, corresponding to four different interrogation pulse spacings.
Mode C
Altitude Reporting Transponder Mode.
Mode C Intruder Alert
A function of certain air traffic control automated systems designed to alert radar controllers to existing or pending situations between a tracked target (known IFR or VFR aircraft) and an untracked target (unknown IFR or VFR aircraft) that requires immediate attention/action.
Model
A copy of a real object which can be life-size, smaller, or larger than the original.
Moderate Icing
The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing equipment or flight diversion is necessary.
Modified T
An RNAV approach design for single or multiple runways where terrain or operational constraints do not allow for the standard T. The “T” may be modified by increasing or decreasing the angle from the corner IAF(s) to the IF or by eliminating one or both corner IAFs.
Moist-adiabatic lapse rate
Saturated-adiabatic lapse rate—The rate of decrease of temperature with height as saturated air is lifted with no gain or loss of heat from outside sources; varies with temperature, being greatest at low temperatures.
Moisture
An all-inclusive term denoting water in any or all of its three states.
Moment
The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (lb-in). Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.
Moment Arm
The distance from a datum to the applied force.
Moment Index
The moment (weight times arm) divided by a reduction factor such as 100 or 1,000 to make the number smaller and reduce the chance of mathematical errors in computing the center of gravity.
Moment Index (Or Index)
A moment divided by a constant such as 100, 1,000, or 10,000. The purpose of using a moment index is to simplify weight and balance computations of airplanes where heavy items and long arms result in large, unmanageable numbers.
Moment Limits vs Weight Envelope
An enclosed area on a graph of three parameters. The diagonal line representing the moment/100 crosses the horizontal line representing the weight at the vertical line representing the CG location in inches aft of the datum. When the lines cross inside the envelope, the aircraft is loaded within its weight and CG limits.
Monitor
(When used with communication transfer) listen on a specific frequency and stand by for instructions. Under normal circumstances do not establish communications.
Monitor Alert (MA)
A function of the TFMS that provides traffic management personnel with a tool for predicting potential capacity problems in individual operational sectors. The MA is an indication that traffic management personnel need to analyze a particular sector for actual activity and to determine the required action(s), if any, needed to control the demand.
Monitor Alert Parameter (MAP)
The number designated for use in monitor alert processing by the TFMS. The MAP is designated for each operational sector for increments of 15 minutes.
Monocoque
A shell-like fuselage design in which the stressed outer skin is used to support the majority of imposed stresses. Monocoque fuselage design may include bulkheads but not stringers.
Monoplanes
Airplanes with a single set of wings.
Monsoon
A wind that in summer blows from sea to a continental interior, bringing copious rain, and in winter blows from the interior to the sea, resulting in sustained dry weather.
Mosaic/Multi-Sensor Mode
Accepts positional data from multiple radar or ADS-B sites. Targets are displayed from a single source within a radar sort box according to the hierarchy of the sources assigned.
Motivation
A need or desire that causes a person to act. Motivation can be positive or negative, tangible or intangible, subtle or obvious.
Mountain wave
A standing wave or lee wave to the lee of a mountain barrier.
Movable Slat
A movable auxiliary airfoil on the leading edge of a wing. It is closed in normal flight but extends at high angles of attack. This allows air to continue flowing over the top of the wing and delays airflow separation.
Movement Area
The runways, taxiways, and other areas of an airport/heliport which are utilized for taxiing/hover taxiing, air taxiing, takeoff, and landing of aircraft, exclusive of loading ramps and parking areas. At those airports/heliports with a tower, specific approval for entry onto the movement area must be obtained from ATC.
Movement Area [ICAO]
That part of an aerodrome to be used for the takeoff, landing and taxiing of aircraft, consisting of the maneuvering area and the apron(s).
Moving Target Indicator
A digital moving target indicator (MTI) radar system for rejection of low velocity "clutter" by utilizing techniques to identify those radar echo returns from targets having radial velocities lower than fixed predetermined values.
MSL Altitude
Altitude expressed in feet measured from mean sea level.
Multi-function display (MFD)
Small screen (CRT or LCD) in an aircraft that can be used to display information to the pilot in numerous configurable ways. Often an MFD will be used in concert with a Primary Flight Display.
Multicom
A mobile service not open to public correspondence used to provide communications essential to conduct the activities being performed by or directed from private aircraft.
Multimedia
A combination of more than one instructional medium. This format can include audio, text, graphics, animations, and video. Recently, multimedia implies a computer-based presentation.
Multiple Runways
The utilization of a dedicated arrival runway(s) for departures and a dedicated departure runway(s) for arrivals when feasible to reduce delays and enhance capacity.
Multiple-choice-type test item
A test item consisting of a question or statement followed by a list of alternative answers or responses.
Mushing
A flight condition caused by slow speed where the control surfaces are marginally effective.
Nacelle
A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven airplanes, the nacelle is normally mounted on the leading edge of the wing.
National Aeronautical Charting Group (NACG)
A Federal agency operating under the FAA, responsible for publishing charts such as the terminal procedures and en route charts. Moved to Aeronautical Information Services AJV-A
National Airspace System
The common network of U.S. airspace; air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information, and manpower and material. Included are system components shared jointly with the military.
National Airspace System (NAS)
Consists of a complex collection of facilities, systems, equipment, procedures, and airports operated by thousands of people to provide a safe and efficient flying environment.
National Beacon Code Allocation Plan Airspace
Airspace over United States territory located within the North American continent between Canada and Mexico, including adjacent territorial waters outward to about boundaries of oceanic control areas (CTA)/Flight Information Regions (FIR).
National defense airspace
Airspace established by a regulation prescribed, or an order issued under, 49 U.S.C. 40103(b)(3).
National Flight Data Center
A facility in Washington D.C., established by FAA to operate a central aeronautical information service for the collection, validation, and dissemination of aeronautical data in support of the activities of government, industry, and the aviation community. The information is published in the National Flight Data Digest.
National Flight Data Digest
A daily (except weekends and Federal holidays) publication of flight information appropriate to aeronautical charts, aeronautical publications, Notices to Airmen, or other media serving the purpose of providing operational flight data essential to safe and efficient aircraft operations.
National Route Program (NRP)
A set of rules and procedures designed to increase the flexibility of user flight planning within published guidelines.
National Search And Rescue Plan
An interagency agreement which provides for the effective utilization of all available facilities in all types of search and rescue missions.
National Security Area (NSA)
Areas consisting of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited. Regulatory prohibitions are disseminated via NOTAMs.
National Transportation Safety Board (NTSB)
A United States Government independent organization responsible for investigations of accidents involving aviation, highways, waterways, pipelines, and railroads in the United States. NTSB is charged by congress to investigate every civil aviation accident in the United States.
Nautical twilight
The period of time before sunrise and after sunset when the sun is not more than 12° below the horizon.
Navaid Classes
VOR, VORTAC, and TACAN aids are classed according to their operational use. The three classes of NAVAIDs are: a. T-Terminal. b. L-Low altitude. c. H-High altitude. Note: The normal service range for T, L, and H class aids is found in the AIM. Certain operational requirements make it necessary to use some of these aids at greater service ranges than specified. Extended range is made possible through flight inspection determinations. Some aids also have lesser service range due to location, terrain, frequency protection, etc. Restrictions to service range are listed in Airport/Facility Directory.
Navigable airspace
Airspace at and above the minimum flight altitudes prescribed by or under this chapter, including airspace needed for safe takeoff and landing.
Navigate
To move between websites on the internet. Navigation is often accomplished by means of links or connections between sites.
Navigation Reference System (NRS)
The NRS is a system of waypoints developed for use within the United States for flight planning and navigation without reference to ground based navigational aids. The NRS waypoints are located in a grid pattern along defined latitude and longitude lines. The initial use of the NRS will be in the high altitude environment in conjunction with the High Altitude Redesign initiative. The NRS waypoints are intended for use by aircraft capable of point-to-point navigation.
Navigation Specification [ICAO]
A set of aircraft and flight crew requirements needed to support performance-based navigation operations within a defined airspace. There are two kinds of navigation specifications: RNP and RNAV. Note: The Performance-based Navigation Manual (Doc 9613), Volume II contains detailed guidance on navigation specifications.
Navigational Aid
Any visual or electronic device airborne or on the surface which provides point-to-point guidance information or position data to aircraft in flight.
Navigational Gap
A navigational course guidance gap, referred to as an MEA gap, describes a distance along an airway or route segment where a gap in navigational signal coverage exists. The navigational gap may not exceed a specific distance that varies directly with altitude.
Negative
“No,” or “permission not granted,” or “that is not correct.”
Negative Contact
Used by pilots to inform ATC that: a. Previously issued traffic is not in sight. It may be followed by the pilot’s request for the controller to provide assistance in avoiding the traffic. b. They were unable to contact ATC on a particular frequency.
Negative Static Stability
The initial tendency of an aircraft to continue away from the original state of equilibrium after being disturbed.
Negative Torque Sensing (NTS)
A system in a turboprop engine that prevents the engine from being driven by the propeller. The NTS increases the blade angle when the propellers try to drive the engine.
Negative vorticity
Vorticity caused by anticyclonic turning; it is associated with downward motion of the air.
Net Weight
The weight of the aircraft less the weight of any chocks or other devices used to hold the aircraft on the scales.
Neutral Static Stability
The initial tendency of an aircraft to remain in a new condition after its equilibrium has been disturbed.
Nickel-Cadmium Battery (NiCad)
A battery made up of alkaline secondary cells. The positive plates are nickel hydroxide, the negative plates are cadmium hydroxide, and potassium hydroxide is used as the electrolyte.
Night
The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.
Night [ICAO]
The hours between the end of evening civil twilight and the beginning of morning civil twilight or such other period between sunset and sunrise as may be specified by the appropriate authority. Note: Civil twilight ends in the evening when the center of the sun’s disk is 6 degrees below the horizon and begins in the morning when the center of the sun’s disk is 6 degrees below the horizon.
Nimbostratus
A principal cloud type, gray colored, often dark, the appearance of which is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground. It is thick enough throughout to blot out the sun.
No Gyro Approach
A radar approach/vector provided in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn” as appropriate.
No Gyro Vector
No Gyro Approach. A radar approach/vector provided in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn” as appropriate.
No procedure turn (NoPT)
Term used with the appropriate course and altitude to denote that the procedure turn is not required.
No Transgression Zone (NTZ)
The NTZ is a 2,000 foot wide zone, located equidistant between parallel runway final approach courses in which flight is not allowed.
No-gyro approach
A radar approach that may be used in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions turn right/left or stop turn, as appropriate.
Noctilucent clouds
Clouds of unknown composition which occur at great heights, probably around 75 to 90 kilometers. They resemble thin cirrus, but usually with a bluish or silverish color, although sometimes orange to red, standing out against a dark night sky. Rarely observed.
Non-Restrictive Routing (NRR)
Portions of a proposed route of flight where a user can flight plan the most advantageous flight path with no requirement to make reference to ground-based NAVAIDs.
Nonapproach Control Tower
Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace. The primary function of a nonapproach control tower is the sequencing of aircraft in the traffic pattern and on the landing area. Nonapproach control towers also separate aircraft operating under instrument flight rules clearances from approach controls and centers. They provide ground control services to aircraft, vehicles, personnel, and equipment on the airport movement area.
Noncommon Route/Portion
That segment of a North American Route between the inland navigation facility and a designated North American terminal.
Noncomposite Separation
Separation in accordance with minima other than the composite separation minimum specified for the area concerned.
Nondirectional Beacon
An L/MF or UHF radio beacon transmitting nondirectional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine his/her bearing to or from the radio beacon and “home” on or track to or from the station. When the radio beacon is installed in conjunction with the Instrument Landing System marker, it is normally called a Compass Locator.
Nondirectional Radio Beacon (NDB)
An L/MF or UHF radio beacon transmitting nondirectional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine bearing to or from the radio beacon and home on or track to or from the station. When the radio beacon is installed in conjunction with the ILS marker, it is normally called a compass locator.
Nonmovement Areas
Taxiways and apron (ramp) areas not under the control of air traffic.
Nonprecision approach
A standard instrument approach procedure in which only horizontal guidance is provided.
Nonprecision approach procedure
A standard instrument approach procedure in which no electronic glide slope is provided.
Nonprecision Approach Runway
An instrument runway served by visual aids and a nonvisual aid providing at least directional guidance adequate for a straight-in approach.
Nonradar
Precedes other terms and generally means without the use of radar, such as: Nonradar Approach, Nonradar Approach Control, Nonradar Arrival, Nonradar Route, and Nonradar Separation.
Nonradar Approach
Used to describe instrument approaches for which course guidance on final approach is not provided by ground-based precision or surveillance radar. Radar vectors to the final approach course may or may not be provided by ATC. Examples of nonradar approaches are VOR, NDB, TACAN, and ILS/MLS approaches.
Nonradar Approach Control
An ATC facility providing approach control service without the use of radar.
Nonradar Arrival
An aircraft arriving at an airport without radar service or at an airport served by a radar facility and radar contact has not been established or has been terminated due to a lack of radar service to the airport.
Nonradar Route
A flight path or route over which the pilot is performing his/her own navigation. The pilot may be receiving radar separation, radar monitoring, or other ATC services while on a nonradar route.
Nonradar Separation
The spacing of aircraft in accordance with established minima without the use of radar; e.g., vertical, lateral, or longitudinal separation.
Nonradar Separation [ICAO]
The separation used when aircraft position information is derived from sources other than radar.
Norm-referenced testing
System of testing in which students are ranked against the performance of other students.
Normal
In meteorology, the value of an element averaged for a given location over a period of years and recognized as a standard.
Normal Category
An airplane that has a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for non-acrobatic operation.
Normal Operating Zone (NOZ)
The NOZ is the operating zone within which aircraft flight remains during normal independent simultaneous parallel ILS approaches.
Normal refraction
Refraction of the radar beam under normal atmospheric conditions; normal radius of curvature of the beam is about 4 times the radius of curvature of the Earth.
Normalizing (Turbonormalizing)
A turbocharger that maintains sea level pressure in the induction manifold at altitude.
North American Route
A numerically coded route preplanned over existing airway and route systems to and from specific coastal fixes serving the North Atlantic. North American Routes consist of the following: a. Common Route/Portion. That segment of a North American Route between the inland navigation facility and the coastal fix. b. Noncommon Route/Portion. That segment of a North American Route between the inland navigation facility and a designated North American terminal. c. Inland Navigation Facility. A navigation aid on a North American Route at which the common route and/or the noncommon route begins or ends. d. Coastal Fix. A navigation aid or intersection where an aircraft transitions between the domestic route structure and the oceanic route structure.
North American Route Program (NRP)
The NRP is a set of rules and procedures which are designed to increase the flexibility of user flight planning within published guidelines.
North Mark
A beacon data block sent by the host computer to be displayed by the ARTS on a 360 degree bearing at a locally selected radar azimuth and distance. The North Mark is used to ensure correct range/azimuth orientation during periods of CENRAP.
North Pacific
An organized route system between the Alaskan west coast and Japan.
Notice To Airmen
A notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, or procedure of, or hazard in the National Airspace System) the timely knowledge of which is essential to personnel concerned with flight operations. There are two types: NOTAM(D) and FDC NOTAM.
Notice to Airmen (NOTAM)
A notice filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location. The authority in turn provides means of disseminating relevant NOTAMs to pilots.
Notices To Airmen Publication
A publication issued every 28 days, designed primarily for the pilot, which contains current NOTAM information considered essential to the safety of flight as well as supplemental data to other aeronautical publications. The contraction NTAP is used in NOTAM text.
Nuisance Alert
An alert in which one or more of the following is true: 1. The alert is generated by a known situation that is not considered an unsafe operation, such as LAHSO or other approved operations. 2. The alert is generated by inaccurate secondary radar data received by the Safety Logic System. 3. One or more of the aircraft involved in the alert is not intending to use a runway (for example, helicopter, pipeline patrol, non-Mode C overflight, etc.).
Numerical forecasting
Forecasting by digital computers solving mathematical equations; used extensively in weather services throughout the world.
Numerical weather prediction
Forecasting by digital computers solving mathematical equations; used extensively in weather services throughout the world.
Numerous Targets Vicinity (Location)
A traffic advisory issued by ATC to advise pilots that targets on the radar scope are too numerous to issue individually.
Objectivity
The singleness of scoring of a test; it does not reflect the biases of the person grading the test.
Obscuration
Denotes sky hidden by surface-based. obscuring phenomena and vertical visibility restricted overhead.
Obscuring phenomena
Any hydrometeor or lithometeor other than clouds; may be surface based or aloft.
Obstacle
An existing object, object of natural growth, or terrain at a fixed geographical location or which may be expected at a fixed location within a prescribed area with reference to which vertical clearance is or must be provided during flight operation.
Obstacle Clearance Surface (OCS)
An inclined or level surface associated with a defined area for obstruction evaluation.
Obstacle Departure Procedure (ODP)
A procedure that provides obstacle clearance. ODPs do not include ATC related climb requirements. In fact, the primary emphasis of ODP design is to use the least onerous route of flight to the en route structure while attempting to accommodate typical departure routes.
Obstacle departure procedures (ODP)
Obstacle clearance protection provided to aircraft in instrument meteorological conditions (IMC).
Obstacle Free Zone
The OFZ is a three dimensional volume of airspace which protects for the transition of aircraft to and from the runway. The OFZ clearing standard precludes taxiing and parked airplanes and object penetrations, except for frangible NAVAID locations that are fixed by function. Additionally, vehicles, equipment, and personnel may be authorized by air traffic control to enter the area using the provisions of FAAO JO 7110.65, Para 3-1-5, VEHICLES/EQUIPMENT/PERSONNEL ON RUNWAYS. The runway OFZ and when applicable, the inner-approach OFZ, and the inner-transitional OFZ, comprise the OFZ.
Obstacle Identification Surface (OIS)
The design of a departure procedure is based on TERPS, a living document that is updated frequently. Departure design criteria assumes an initial climb of 200 feet per NM after crossing the departure end of the runway (DER) at a height of at least 35 feet above the ground. Assuming a 200 feet per NM climb, the departure is structured to provide at least 48 feet per NM of clearance above objects that do not penetrate the obstacle slope. The slope, known as the obstacle identification slope (OIS), is based on a 40 to 1 ratio, which is the equivalent of a 152-foot per NM slope.
Obstruction
Any object/obstacle exceeding the obstruction standards specified by 14 CFR Part 77, Subpart C.
Obstruction Light
A light or one of a group of lights, usually red or white, frequently mounted on a surface structure or natural terrain to warn pilots of the presence of an obstruction.
Obstruction lights
Lights that can be found both on and off an airport to identify obstructions.
Occluded front
A composite of two fronts as a cold front overtakes a warm front or quasi-stationary front. (commonly called occlusion or frontal occlusion).
Occlusion
Same as occluded front—a composite of two fronts as a cold front overtakes a warm front or quasi-stationary front. (commonly called occlusion or frontal occlusion).
Oceanic Airspace
Airspace over the oceans of the world, considered international airspace, where oceanic separation and procedures per the International Civil Aviation Organization are applied. Responsibility for the provisions of air traffic control service in this airspace is delegated to various countries, based generally upon geographic proximity and the availability of the required resources.
Oceanic Display And Planning System
An automated digital display system which provides flight data processing, conflict probe, and situation display for oceanic air traffic control.
Oceanic Navigational Error Report
A report filed when an aircraft exiting oceanic airspace has been observed by radar to be off course. ONER reporting parameters and procedures are contained in FAAO 7110.82, Monitoring of Navigational Performance In Oceanic Areas.
Oceanic Published Route
A route established in international airspace and charted or described in flight information publications, such as Route Charts, DOD Enroute Charts, Chart Supplements, NOTAMs, and Track Messages.
Oceanic Transition Route
An ATS route established for the purpose of transitioning aircraft to/from an organized track system.
Octane
The rating system of aviation gasoline with regard to its anti-detonating qualities.
Off Course
A term used to describe a situation where an aircraft has reported a position fix or is observed on radar at a point not on the ATC-approved route of flight.
Off-Airway Routes
The FAA prescribes altitudes governing the operation of aircraft under IFR for off airway routes in a similar manner to those on federal airways, jet routes, area navigation low or high altitude routes, and other direct routes for which an MEA is designated.
Off-Route Obstruction Clearance Altitude (OROCA)
An off-route altitude that provides obstruction clearance with a 1,000 foot buffer in non-mountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground based navigational aids, air traffic control radar, or communications coverage.
Off-Route Vector
A vector by ATC which takes an aircraft off a previously assigned route. Altitudes assigned by ATC during such vectors provide required obstacle clearance.
Offset Parallel Runways
Staggered runways having centerlines which are parallel.
Offshore/Control Airspace Area
That portion of airspace between the U.S. 12 NM limit and the oceanic CTA/FIR boundary within which air traffic control is exercised. These areas are established to provide air traffic control services. Offshore/Control Airspace Areas may be classified as either Class A airspace or Class E airspace.
Omega
An RNAV system designed for long-range navigation based upon ground-based electronic navigational aid signals.
Omission error
The failure to anticipate significant instrument indications following attitude changes; for example, concentrating on pitch control while forgetting about heading or roll information, resulting in erratic control of heading and bank.
On Course
A. Used to indicate that an aircraft is established on the route centerline.
B. Used by ATC to advise a pilot making a radar approach that his/her aircraft is lined up on the final approach course.
On-Course Indication
An indication on an instrument, which provides the pilot a visual means of determining that the aircraft is located on the centerline of a given navigational track, or an indication on a radar scope that an aircraft is on a given track.
One-Minute Weather
The most recent one minute updated weather broadcast received by a pilot from an uncontrolled airport ASOS/AWSS/AWOS.
Operate
With respect to aircraft, use, cause to use or authorize to use aircraft, for the purpose (except as provided in §91.13 of this chapter) of air navigation including the piloting of aircraft, with or without the right of legal control (as owner, lessee, or otherwise).
Operational
Due Regard.
Operational control
With respect to a flight, the exercise of authority over initiating, conducting or terminating a flight.
Operations Specifications (OpsSpecs)
A published document providing the conditions under which an air carrier and operator for compensation or hire must operate in order to retain approval from the FAA.
Operations Specifications [ICAO]
The authorizations, conditions and limitations associated with the air operator certificate and subject to the conditions in the operations manual.
Opposite Direction Aircraft
Aircraft are operating in opposite directions when: a. They are following the same track in reciprocal directions; or b. Their tracks are parallel and the aircraft are flying in reciprocal directions; or c. Their tracks intersect at an angle of more than 135°.
Optical illusion
A misleading visual image. For the purpose of this handbook, the term refers to the brains misinterpretation of features on the ground associated with landing, which causes a pilot to misread the spatial relationships between the aircraft and the runway.
Option Approach
An approach requested and conducted by a pilot which will result in either a touch-and-go, missed approach, low approach, stop-and-go, or full stop landing.
Organized Track System
A series of ATS routes which are fixed and charted; i.e., CEP, NOPAC, or flexible and described by NOTAM; i.e., NAT TRACK MESSAGE.
Orientation
Awareness of the position of the aircraft and of oneself in relation to a specific reference point.
Orographic
Of, pertaining to, or caused by mountains as in orographic clouds, orographic lift, or orographic precipitation.
Orographic Cloud
A cloud that usually results from air flowing upslope from terrain and being cooled adiabatically.
Otolith organ
An inner ear organ that detects linear acceleration and gravity orientation.
Out
The conversation is ended and no response is expected.
Outer Area (Associated With Class C Airspace)
Nonregulatory airspace surrounding designated Class C airspace airports wherein ATC provides radar vectoring and sequencing on a full-time basis for all IFR and participating VFR aircraft. The service provided in the outer area is called Class C service which includes: IFR/IFR-standard IFR separation; IFR/VFR-traffic advisories and conflict resolution; and VFR/VFR-traffic advisories and, as appropriate, safety alerts. The normal radius will be 20 nautical miles with some variations based on site-specific requirements. The outer area extends outward from the primary Class C airspace airport and extends from the lower limits of radar/radio coverage up to the ceiling of the approach control’s delegated airspace excluding the Class C charted area and other airspace as appropriate.
Outer Compass Locator
Compass Locator.
Outer Compass Locator (LOM)
A compass locator installed at the site of the outer marker of an instrument landing system.
Outer Fix
A general term used within ATC to describe fixes in the terminal area, other than the final approach fix. Aircraft are normally cleared to these fixes by an Air Route Traffic Control Center or an Approach Control Facility. Aircraft are normally cleared from these fixes to the final approach fix or final approach course.
Outer Fix Arc
A semicircle, usually about a 50-70 mile radius from a meter fix, usually in high altitude, which is used by CTAS/HOST to calculate outer fix times and determine appropriate sector meter list assignments for aircraft on an established arrival route that will traverse the arc.
Outer Fix Time
A calculated time to depart the outer fix in order to cross the vertex at the ACLT. The time reflects descent speed adjustments and any applicable delay time that must be absorbed prior to crossing the meter fix.
Outer marker
A marker beacon at or near the glide slope intercept altitude of an ILS approach. It is normally located four to seven miles from the runway threshold on the extended centerline of the runway.
Outside air temperature (OAT)
The measured or indicated air temperature (IAT) corrected for compression and friction heating. Also referred to as true air temperature.
Over
My transmission is ended; I expect a response.
Over-the-top
Above the layer of clouds or other obscuring phenomena forming the ceiling.
Overboost
A condition in which a reciprocating engine has exceeded the maximum manifold pressure allowed by the manufacturer. Can cause damage to engine components.
Overcontrolling
Using more movement in the control column than is necessary to achieve the desired pitch-and bank condition.
Overhead Maneuver
A series of predetermined maneuvers prescribed for aircraft (often in formation) for entry into the visual flight rules (VFR) traffic pattern and to proceed to a landing. An overhead maneuver is not an instrument flight rules (IFR) approach procedure. An aircraft executing an overhead maneuver is considered VFR and the IFR flight plan is cancelled when the aircraft reaches the “initial point” on the initial approach portion of the maneuver. The pattern usually specifies the following: a. The radio contact required of the pilot. b. The speed to be maintained. c. An initial approach 3 to 5 miles in length. d. An elliptical pattern consisting of two 180 degree turns. e. A break point at which the first 180 degree turn is started. f. The direction of turns. g. Altitude (at least 500 feet above the conventional pattern). h. A “Roll-out” on final approach not less than 1/4 mile from the landing threshold and not less than 300 feet above the ground.
Overhead question
In the guided discussion method, a question directed to the entire group in order to stimulate thought and discussion from the entire group. An overhead question may be used by an instructor as the lead-off question.
Overlying Center
The ARTCC facility that is responsible for arrival/departure operations at a specific terminal.
Overpower
To use more power than required for the purpose of achieving a faster rate of airspeed change.
Overseas air commerce
The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation or navigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in any State of the United States, or the District of Columbia, and any place in a territory or possession of the United States; or between a place in a territory or possession of the United States, and a place in any other territory or possession of the United States.
Overseas air transportation
The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft, in commerce:
(1) Between a place in a State or the District of Columbia and a place in a possession of the United States; or
(2) Between a place in a possession of the United States and a place in another possession of the United States; whether that commerce moves wholly by aircraft or partly by aircraft and partly by other forms of transportation.
Overspeed
A condition in which an engine has produced more r.p.m. than the manufacturer recommends, or a condition in which the actual engine speed is higher than the desired engine speed as set on the propeller control.
Overtemp
A condition in which a device has reached a temperature above that approved by the manufacturer or any exhaust temperature that exceeds the maximum allowable for a given operating condition or time limit. Can cause internal damage to an engine.
Overtorque
A condition in which an engine has produced more torque (power) than the manufacturer recommends, or a condition in a turboprop or turboshaft engine where the engine power has exceeded the maximum allowable for a given operating condition or time limit. Can cause internal damage to an engine.
Ozone
An unstable form of oxygen; heaviest concentrations are in the stratosphere; corrosive to some metals; absorbs most ultraviolet solar radiation.
P Time
Proposed Departure Time.
P-Factor
A tendency for an aircraft to yaw to the left due to the for descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.
P-static
Precipitation Static.
Pan-Pan
The international radio-telephony urgency signal. When repeated three times, indicates uncertainty or alert followed by the nature of the urgency.
Parachute
A device used or intended to be used to retard the fall of a body or object through the air.
Parallel ILS Approaches
Approaches to parallel runways by IFR aircraft which, when established inbound toward the airport on the adjacent final approach courses, are radar-separated by at least 2 miles.
Parallel MLS Approaches
Approaches to parallel runways by IFR aircraft which, when established inbound toward the airport on the adjacent final approach courses, are radar-separated by at least 2 miles.
Parallel Offset Route
A parallel track to the left or right of the designated or established airway/route. Normally associated with Area Navigation (RNAV) operations.
Parallel Runways
Two or more runways at the same airport whose centerlines are parallel. In addition to runway number, parallel runways are designated as L (left) and R (right) or, if three parallel runways exist, L (left), C (center), and R (right).
Parallels
Lines of latitude.
Parasite Drag
That part of total drag created by the design or shape of airplane parts. Parasite drag increases with an increase in airspeed.
Parcel
A small volume of air, small enough to contain uniform distribution of its meteorological properties, and large enough to remain relatively self-contained and respond to all meteorological processes. No specific dimensions have been defined, however, the order of magnitude of 1 cubic foot has been suggested.
Partial obscuration
A designation of sky cover when part of the sky is hidden by surface based obscuring phenomena.
Passenger
Any person on board an aircraft other than a crewmember, FAA personnel, manufacturer personnel required for type certification, or a person receiving or providing flight training, checking, or testing as authorized by this part.
Payload
(GAMA) Weight of occupants, cargo, and baggage.
Payload (GAMA)
The weight of occupants, cargo, and baggage.
Perceptions
The basis of all learning, perceptions result when a person gives meaning to external stimuli or sensations. Meaning derived from perception is influenced by an individual’s experience and many other factors.
Performance-Based Navigation (PBN) [ICAO]
Area navigation based on performance requirements for aircraft operating along an ATS route, on an instrument approach procedure or in a designated airspace. Note: Performance requirements are expressed in navigation specifications (RNAV specification, RNP specification) in terms of accuracy, integrity, continuity, availability, and functionality needed for the proposed operation in the context of a particular airspace concept.
Performance-based objectives
A statement of purpose for a lesson or instructional period that includes three elements: a description of the skill or behavior desired of the student, a set of conditions under which the measurement will be taken, and a set of criteria describing the standard used to measure accomplishment of the objective.
Permanent Ballast (fixed ballast)
A weight permanently installed in an aircraft to bring its center of gravity into allowable limits. Permanent ballast is part of the aircraft empty weight.
Permanent Echo
Radar signals reflected from fixed objects on the earth’s surface; e.g., buildings, towers, terrain. Permanent echoes are distinguished from “ground clutter” by being definable locations rather than large areas. Under certain conditions they may be used to check radar alignment.
Person
An individual, firm, partnership, corporation, company, association, joint-stock association, or governmental entity. It includes a trustee, receiver, assignee, or similar representative of any of them.
Personal computer-based aviation training device (PCATD)
A device which uses software which can be displayed on a personal computer to replicate the instrument panel of an airplane. A PCATD must replicate a type of airplane or family of airplanes and meet the virtual control requirements specified in AC 61-126.
Personality
The embodiment of personal traits and characteristics of an individual that are set at a very early age and are extremely resistant to change.
Photo Reconnaissance
Military activity that requires locating individual photo targets and navigating to the targets at a preplanned angle and altitude. The activity normally requires a lateral route width of 16 NM and altitude range of 1,500 feet to 10,000 feet AGL.
Phugoid oscillations
Long-period oscillations of an aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle of attack remains constant, and the pilot often corrects for phugoid oscillations without even being aware of them.
Physical organism
A perception factor that describes a person’s ability to sense the world around them.
Pilot balloon
A small free-lift balloon used to determine the speed and direction of winds in the upper air.
Pilot balloon observation (commonly called PIBAL)
A method of winds-aloft observation by visually tracking a pilot balloon.
Pilot Briefing
A service provided by the FSS to assist pilots in flight planning. Briefing items may include weather information, NOTAMs, military activities, flow control information, and other items as requested.
Pilot Briefing Information
The current format for charted IAPs issued by NACO. The information is presented in a logical order facilitating pilot briefing of the procedures. Charts include formatted information required for quick pilot or flight crew reference located at the top of the chart.
Pilot error
Pilot action/inaction or decision/indecision causing or contributing to an accident or incident.
Pilot in command
The person who:
(1) Has final authority and responsibility for the operation and safety of the flight;
(2) Has been designated as pilot in command before or during the flight; and
(3) Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.
Pilot in command (PIC)
The pilot responsible for the operation and safety of an aircraft.
Pilot report (PIREP)
Report of meteorological phenomena encountered by aircraft.
Pilot Weather Report
A report of meteorological phenomena encountered by aircraft in flight.
Pilot Weather Report (PIREP)
A report from a pilot of meteorological phenomena usually transmitted in a prescribed format. The letters “UA” identify the message as a routine PIREP while the letters “UUA” identify an urgent PIREP.
Pilot-in-command (PIC)
The pilot responsible for the operation and safety of an aircraft.
Pilotage
Navigation by visual reference to landmarks.
Pilot’s Discretion
When used in conjunction with altitude assignments, means that ATC has offered the pilot the option of starting climb or descent whenever he/she wishes and conducting the climb or descent at any rate he/she wishes. He/she may temporarily level off at any intermediate altitude. However, once he/she has vacated an altitude, he/she may not return to that altitude.
Pilot’s Operating Handbook (POH)
A document developed by the airplane manufacturer and contains the FAA approved Airplane Flight Manual (AFM) information.
Pilot’s Operating Handbook/Airplane Flight Manual (POH/AFM)
FAA-approved documents published by the airframe manufacturer that list the operating conditions for a particular model of aircraft.
Pirep
Pilot Weather Report.
Piston Engine
A reciprocating engine.
Pitch
The rotation of an airplane about its lateral axis, or on a propeller, the blade angle as measured from plane of rotation.
Pitch Point
A fix/waypoint that serves as a transition point from a departure procedure or the low altitude ground-based navigation structure into the high altitude waypoint system.
Pitch setting
The propeller blade setting as determined by the blade angle measured in a manner, and at a radius, specified by the instruction manual for the propeller.
Pitot pressure
Ram air pressure used to measure airspeed.
Pitot-static head
A combination pickup used to sample pitot pressure and static air pressure.
Pivotal Altitude
A specific altitude at which, when an airplane turns at a given groundspeed, a projecting of the sighting reference line to a selected point on the ground will appear to pivot on that point.
Plan position indicator (PPI) scope
A radar indicator scope displaying range and azimuth of targets in polar coordinates.
Plan view
The overhead view of an approach procedure on an instrument approach chart. The plan view depicts the routes that guide the pilot from the en route segments to the IAF.
Planform
The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.
Plans Display
A display available in URET that provides detailed flight plan and predicted conflict information in textual format for requested Current Plans and all Trial Plans.
Plow wind
The spreading downdraft of a thunderstorm; a strong, straight-line wind in advance of the storm. Also called first gust.
Pneumatic
Operation by the use of compressed air.
Pneumatic Systems
The power system in an aircraft used for operating such items as landing gear, brakes, and wing flaps with compressed air as the operating fluid.
Point Out
Radar Point Out.
Point-in-Space (PinS)Approach
An approach normally developed to heliports that do not meet the IFR heliport design standards but meet the standards for a VFR heliport. A helicopter PinS approach can be developed using conventional NAVAIDs or RNAV systems. These procedures have either a VFR or visual segment between the MAP and the landing area. The procedure will specify a course and distance from the MAP to the heliport(s) and include a note to proceed VFR or visually from the MAP to the heliport, or conduct the missed approach.
Point-in-space approach
A type of helicopter instrument approach procedure to a missed approach point more than 2,600 feet from an associated helicopter landing area.
Point-To-Point (PTP)
A level of NRR service for aircraft that is based on traditional waypoints in their FMSs or RNAV equipage.
Polar air
An air mass with characteristics developed over high latitudes, especially within the subpolar highs. Continental polar air (cP) has cold surface temperatures, low moisture content, and, especially in its source regions, has great stability in the lower layers. It is shallow in comparison with Arctic air. Maritime polar (mP) initially possesses similar properties to those of continental polar air, but in passing over warmer water it becomes unstable with a higher moisture content. Compare tropical air.
Polar front
The semipermanent, semicontinuous front separating air masses of tropical and polar origins.
Polar Track Structure
A system of organized routes between Iceland and Alaska which overlie Canadian MNPS Airspace.
Poor judgment chain
A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of a poor judgment chain are: (1) one bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. Aeronautical decision- making is intended to break the poor judgment chain before it can cause an accident or incident.
Porpoising
Oscillating around the lateral axis of the aircraft during landing.
Position error
Error in the indication of the altimeter, ASI, and VSI caused by the air at the static system entrance not being absolutely still.
Position Lights
Lights on an aircraft consisting of a red light on the left wing, a green light on the right wing, and a white light on the tail. CFRs require that these lights be displayed in flight from sunset to sunrise.
Position report
A report over a known location as transmitted by an aircraft to ATC.
Position Symbol
A computer-generated indication shown on a radar display to indicate the mode of tracking.
Positive control
Control of all air traffic, within designated airspace, by air traffic control.
Positive Course Guidance (PCG)
A continuous display of navigational data that enables an aircraft to be flown along a specific course line, e.g., radar vector, RNAV, ground-based NAVAID.
Positive Static Stability
The initial tendency to return to a state of equilibrium when disturbed from that state.
Positive vorticity
Vorticity caused by cyclonic turning; it is associated with upward motion of the air.
Potable Water
Water carried in an aircraft for the purpose of drinking.
Power
Implies work rate or units of work per unit of time, and as such, it is a function of the speed at which the force is developed. The term “power required” is generally associated with reciprocating engines.
Power density
In radar meteorology the amount of radiated energy per unit cross sectional area in the radar beam.
Power Distribution Bus
A Bus Bar. An electrical power distribution point to which several circuits may be connected. It is often a solid metal strip having a number of terminals installed on it.
Power Lever
The cockpit lever connected to the fuel control unit scheduling fuel flow to the combustion chambers of a turbine engine.
Powered parachute
A powered aircraft comprised of a flexible or semi-rigid wing connected to a fuselage so that the wing is not in position for flight until the aircraft is in motion. The fuselage of a powered parachute contains the aircraft engine, a seat for each occupant and is attached to the aircraft’s landing gear.
Powered-lift
A heavier-than-air aircraft capable of vertical takeoff, vertical landing, and low speed flight that depends principally on engine-driven lift devices or engine thrust for lift during these flight regimes and on nonrotating airfoil(s) for lift during horizontal flight.
Powerplant
A complete engine and propeller combination with accessories.
Practical Slip Limit
The maximum slip an aircraft is capable of performing due to rudder travel limits.
Practical Test Standards (PTS)
An FAA published list of standards which must be met for the issuance of a particular pilot certificate or rating. FAA inspectors and designated pilot examiners use these standards when conducting pilot practical tests and flight instructors should use the PTS while preparing applicants for practical tests. (Obsolete term, replaced by Airman Certification Standards)
Practice Instrument Approach
An instrument approach procedure conducted by a VFR or an IFR aircraft for the purpose of pilot training or proficiency demonstrations.
Pre-Departure Clearance
An application with the Terminal Data Link System (TDLS) that provides clearance information to subscribers, through a service provider, in text to the cockpit or gate printer.
Pre-Flight Pilot Briefing
Pilot Briefing.
Prearranged Coordination
A standardized procedure which permits an air traffic controller to enter the airspace assigned to another air traffic controller without verbal coordination. The procedures are defined in a facility directive which ensures standard separation between aircraft.
Prearranged Coordination Procedures
A facility’s standardized procedure that describes the process by which one controller shall allow an aircraft to penetrate or transit another controller’s airspace in a manner that assures standard separation without individual coordination for each aircraft.
Precession
The tilting or turning of a gyro in response to deflective forces causing slow drifting and erroneous indications in gyroscopic instruments.
Precipitation
Any or all forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the surface. It is a major class of hydrometeor, distinguished from cloud and virga in that it must reach the surface.
Precipitation attenuation
Reduction of power density because of absorption or reflection of energy by precipitation.
Precipitation Radar Weather Descriptions
Existing radar systems cannot detect turbulence. However, there is a direct correlation between the degree of turbulence and other weather features associated with thunderstorms and the weather radar precipitation intensity. Controllers will issue (where capable) precipitation intensity as observed by radar when using weather and radar processor (WARP) or NAS ground based digital radars with weather capabilities. When precipitation intensity information is not available, the intensity will be described as UNKNOWN. When intensity levels can be determined, they shall be described as: a. LIGHT (< 30 dBZ b. MODERATE (30 to 40 dBZ c. HEAVY (> 40 to 50 dBZ d. EXTREME (> 50 dBZ
Precipitation static (P-static)
A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it.
Precision approach
A standard instrument approach procedure in which both vertical and horizontal guidance is provided.
Precision approach path indicator (PAPI)
A system of lights similar to the VASI, but consisting of one row of lights in two- or four-light systems. A pilot on the correct glide slope will see two white lights and two red lights. See VASI.
Precision approach procedure
A standard instrument approach procedure in which an electronic glide slope is provided, such as ILS and PAR.
Precision Approach Radar
Radar equipment in some ATC facilities operated by the FAA and/or the military services at joint-use civil/military locations and separate military installations to detect and display azimuth, elevation, and range of aircraft on the final approach course to a runway. This equipment may be used to monitor certain nonradar approaches, but is primarily used to conduct a precision instrument approach (PAR) wherein the controller issues guidance instructions to the pilot based on the aircraft’s position in relation to the final approach course (azimuth), the glidepath (elevation), and the distance (range) from the touchdown point on the runway as displayed on the radar scope. Note: The abbreviation “PAR” is also used to denote preferential arrival routes in ARTCC computers.
Precision approach radar (PAR)
A type of radar used at an airport to guide an aircraft through the final stages of landing, providing horizontal and vertical guidance. The radar operator directs the pilot to change heading or adjust the descent rate to keep the aircraft on a path that allows it to touch down at the correct spot on the runway.
Precision Approach Radar [ICAO]
Primary radar equipment used to determine the position of an aircraft during final approach, in terms of lateral and vertical deviations relative to a nominal approach path, and in range relative to touchdown. Note: Precision approach radars are designed to enable pilots of aircraft to be given guidance by radio communication during the final stages of the approach to land.
Precision Approach Runway, Category I
An instrument runway served by ILS and visual aids intended for operations down to 60 m (200 feet) decision height and down to an RVR of the order of 800 m.
Precision Approach Runway, Category II
An instrument runway served by ILS and visual aids intended for operations down to 30 m (100 feet) decision height and down to an RVR of the order of 400 m.
Precision Approach Runway, Category III
An instrument runway served by ILS to and along the surface of the runway and: 1. Intended for operations down to an RVR of the order of 200 m (no decision height being applicable) using visual aids during the final phase of landing; 2. Intended for operations down to an RVR of the order of 50 m (no decision height being applicable) using visual aids for taxiing; 3. Intended for operations without reliance on visual reference for landing or taxiing. Note: Visual aids need not necessarily be matched to the scale of nonvisual aids provided. The criterion for the selection of visual aids is the conditions in which operations are intended to be conducted.
Precision Obstacle Free Zone (POFZ)
An 800 foot wide by 200 foot long area centered on the runway centerline adjacent to the threshold designed to protect aircraft flying precision approaches from ground vehicles and other aircraft when ceiling is less than 250 feet or visibility is less than 3/4 statute mile (or runway visual range below 4,000 feet.
Precision Runway Monitor (PRM)
Provides air traffic controllers with high precision secondary surveillance data for aircraft on final approach to parallel runways that have extended centerlines separated by less than 4,300 feet. High resolution color monitoring displays (FMA) are required to present surveillance track data to controllers along with detailed maps depicting approaches and a no transgression zone.
Predictive Wind Shear Alert System (PWS)
A self-contained system used onboard some aircraft to alert the flight crew to the presence of a potential wind shear. PWS systems typically monitor 3 miles ahead and 25 degrees left and right of the aircraft’s heading at or below 1200’ AGL. Departing flights may receive a wind shear alert after they start the takeoff roll and may elect to abort the takeoff. Aircraft on approach receiving an alert may elect to go around or perform a wind shear escape maneuver.
Preferential Arrival Route PAR
A specific arrival route from an appropriate en route point to an airport or terminal area. It may be included in a Standard Terminal Arrival (STAR) or a Preferred IFR Route. The abbreviation “PAR” is used primarily within the ARTCC and should not be confused with the abbreviation for Precision Approach Radar.
Preferential Departure And Arrival Route (PDAR)
A route between two terminals which are within or immediately adjacent to one ARTCC’s area. PDARs are not synonymous with Preferred IFR Routes but may be listed as such as they do accomplish essentially the same purpose.
Preferential Departure Route (PDR)
A specific departure route from an airport or terminal area to an en route point where there is no further need for flow control. It may be included in an instrument Departure Procedure (DP) or a Preferred IFR Route.
Preferential Routes
Preferential routes (PDRs, PARs, and PDARs) are adapted in ARTCC computers to accomplish inter/intrafacility controller coordination and to assure that flight data is posted at the proper control positions. Locations having a need for these specific inbound and outbound routes normally publish such routes in local facility bulletins, and their use by pilots minimizes flight plan route amendments. When the workload or traffic situation permits, controllers normally provide radar vectors or assign requested routes to minimize circuitous routing. Preferential routes are usually confined to one ARTCC’s area and are referred to by the following names or acronyms: Preferential Departure Route (PDR), Preferential Arrival Route (PAR), and Preferential Departure and Arrival Route (PDAR).
Preferred IFR Routes
A system of preferred IFR routes guides you in planning your route of flight to minimize route changes during the operational phase of flight, and to aid in the efficient orderly management of air traffic using federal airways.
Preignition
Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel/air mixture.
Preparation
The first step of the teaching process, which consists of determining the scope of the lesson, the objectives, and the goals to be attained. This portion also includes making certain all necessary supplies are on hand. When using the telling-and-doing technique of flight instruction, this step is accomplished prior to the flight lesson.
Presentation
The second step of the teaching process, which consists of delivering information or demonstrating the skills that make up the lesson. The delivery could be by either the lecture method or demonstration-performance method. In the telling-and-doing technique of flight instruction, this is the segment in which the instructor both talks about and performs the procedure.
Pressure altimeter
An aneroid barometer with a scale graduated in altitude instead of pressure using standard atmospheric pressure-height relationships; shows indicated altitude (not necessarily true altitude); may be set to measure altitude (indicated) from any arbitrarily chosen level.
Pressure Altitude
The altitude indicated when the altimeter setting window (barometric scale) is adjusted to 29.92. This is the altitude above the standard datum plane, which is a theoretical plane where air pressure (corrected to 15ºC) equals 29.92 in. Hg. Pressure altitude is used to compute density altitude, true altitude, true airspeed, and other performance data.
Pressure demand oxygen system
A demand oxygen system that supplies 100 percent oxygen at sufficient pressure above the altitude where normal breathing is adequate. Also referred to as a pressure breathing system.
Pressure gradient
The rate of decrease of pressure per unit distance at a fixed time.
Pressure jump
A sudden, significant increase in station pressure.
Pressure tendency
Barometric tendency. The change of barometric pressure within a specified period of time. In aviation weather observation, routinely determined periodically, usually for a 3-hour period.
Pretest
A test used to determine whether a student has the necessary qualifications to begin a course of study. Also used to determine the level of knowledge a student has in relation to the material that will be presented in the course.
Prevailing easterlies
The broad current or pattern of persistent easterly winds in the Tropics and in polar regions.
Prevailing visibility
The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle (which is not necessarily continuous).
Prevailing westerlies
The dominant west-to-east motion of the atmosphere, centered over middle latitudes of both hemispheres.
Prevailing wind
Direction from which the wind blows most frequently.
Preventive maintenance
Simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations.
Primacy
A principle of learning in which the first experience of something often creates a strong, almost unshakable impression. The importance to an instructor is that the first time something is demonstrated, it must be shown correctly since that experience is the one most likely to be remembered by the student.
Primary and supporting
A method of attitude instrument flying using the instrument that provides the most direct indication of attitude and performance.
Primary flight display (PFD)
A display that provides increased situational awareness to the pilot by replacing the traditional six instruments used for instrument flight with an easy-to-scan display that provides the horizon, airspeed, altitude, vertical speed, trend, trim, rate of turn among other key relevant indications.
Primary Radar
A radar system in which a minute portion of a radio pulse transmitted from a site is reflected by an object and then received back at that site for processing and display at an air traffic control facility.
Primary Radar Target
An analog or digital target, exclusive of a secondary radar target, presented on a radar display.
Principal Operations Inspector (POI)
Scheduled air carriers and operators for compensation or hire are assigned a principal operations inspector (POI) who works directly with the company and coordinates FAA operating approval.
Problem-based learning
Lessons in such a way as to confront students with problems that are encountered in real life which force them to reach real-world solutions.
Procedure turn
A maneuver prescribed when it is necessary to reverse direction to establish an aircraft on the intermediate approach segment or final approach course.
Procedure Turn Inbound
That point of a procedure turn maneuver where course reversal has been completed and an aircraft is established inbound on the intermediate approach segment or final approach course. A report of “procedure turn inbound” is normally used by ATC as a position report for separation purposes.
Procedure Turn [ICAO]
A maneuver in which a turn is made away from a designated track followed by a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of the designated track. Note 1: Procedure turns are designated “left” or “right” according to the direction of the initial turn. Note 2: Procedure turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual approach procedure.
Profile Descent
An uninterrupted descent (except where level flight is required for speed adjustment; e.g., 250 knots at 10,000 feet MSL) from cruising altitude/level to interception of a glideslope or to a minimum altitude specified for the initial or intermediate approach segment of a nonprecision instrument approach. The profile descent normally terminates at the approach gate or where the glideslope or other appropriate minimum altitude is intercepted.
Profile Drag
The total of the skin friction drag and form drag for a two-dimensional airfoil section.
Profile view
Side view of an IAP chart illustrating the vertical approach path altitudes, headings, distances, and fixes.
Prognostic chart (contracted PROG)
A chart of expected or forecast conditions.
Programmable Indicator Data Processor (PIDP)
A type or Automated Radar Terminal System (ARTS). The PIDP is a modification to the AN/TPX-42 interrogator system currently installed in fixed RAPCONs. The PIDP detects, tracks, and predicts secondary radar aircraft targets. These are displayed by means of computer-generated symbols and alphanumeric characters depicting flight identification, aircraft altitude, ground speed, and flight plan data. Although primary radar targets are not tracked, they are displayed coincident with the secondary radar targets as well as with the other symbols and alphanumerics. The system has the capability of interfacing with ARTCCs.
Progress Report
Position Report.
Progressive Taxi
Precise taxi instructions given to a pilot unfamiliar with the airport or issued in stages as the aircraft proceeds along the taxi route.
Prohibited area
Designated airspace within which flight of aircraft is prohibited.
Prohibited Area [ICAO]
An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is prohibited.
Prominent Obstacle
An obstacle that meets one or more of the following conditions: a. An obstacle which stands out beyond the adjacent surface of surrounding terrain and immediately projects a noticeable hazard to aircraft in flight. b. An obstacle, not characterized as low and close in, whose height is no less than 300 feet above the departure end of takeoff runway (DER) elevation, is within 10NM from the DER, and that penetrates that airport/heliport’s diverse departure obstacle clearance surface (OCS). c. An obstacle beyond 10NM from an airport/heliport that requires an obstacle departure procedure (ODP) to ensure obstacle avoidance.
Propeller
A device for propelling an aircraft that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes the control components normally supplied by its manufacturer.
Propeller Blade Angle
The angle between the propeller chord and the propeller plane of rotation.
Propeller Lever
The control on a free power turbine turboprop that controls propeller speed and the selection for propeller feathering.
Propeller Slipstream
The volume of air accelerated behind a propeller producing thrust.
Propeller Synchronization
A condition in which all of the propellers have their pitch automatically adjusted to maintain a constant r.p.m. among all of the engines of a multiengine aircraft.
Propeller/rotor modulation error
Certain propeller RPM settings or helicopter rotor speeds can cause the VOR course deviation indicator (CDI) to fluctuate as much as ±6°. Slight changes to the RPM setting will normally smooth out this roughness.
Proposed Boundary Crossing Time
Each center has a PBCT parameter for each internal airport. Proposed internal flight plans are transmitted to the adjacent center if the flight time along the proposed route from the departure airport to the center boundary is less than or equal to the value of PBCT or if airport adaptation specifies transmission regardless of PBCT.
Proposed Departure Time
The time that the aircraft expects to become airborne.
Protected Airspace
The airspace on either side of an oceanic route/track that is equal to one-half the lateral separation minimum except where reduction of protected airspace has been authorized.
Pseudo-adiabatic lapse rate
Saturated-adiabatic lapse rate. The rate of decrease of temperature with height as saturated air is lifted with no gain or loss of heat from outside sources; varies with temperature, being greatest at low temperatures.
Psychomotor domain
A grouping of levels of learning associated with physical skill levels which range from perception through set, guided response, mechanism, complex overt response, and adaptation to origination.
Psychrometer
An instrument consisting of a wet-bulb and a dry-bulb thermometer for measuring wet-bulb and dry-bulb temperature; used to determine water vapor content of the air.
Public aircraft
Any of the following aircraft when not being used for a commercial purpose or to carry an individual other than a crewmember or qualified non-crewmember:
(1) An aircraft used only for the United States Government; an aircraft owned by the Government and operated by any person for purposes related to crew training, equipment development, or demonstration; an aircraft owned and operated by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments; or an aircraft exclusively leased for at least 90 continuous days by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments.
(i) For the sole purpose of determining public aircraft status, commercial purposes means the transportation of persons or property for compensation or hire, but does not include the operation of an aircraft by the armed forces for reimbursement when that reimbursement is required by any Federal statute, regulation, or directive, in effect on November 1, 1999, or by one government on behalf of another government under a cost reimbursement agreement if the government on whose behalf the operation is conducted certifies to the Administrator of the Federal Aviation Administration that the operation is necessary to respond to a significant and imminent threat to life or property (including natural resources) and that no service by a private operator is reasonably available to meet the threat.
(ii) For the sole purpose of determining public aircraft status, governmental function means an activity undertaken by a government, such as national defense, intelligence missions, firefighting, search and rescue, law enforcement (including transport of prisoners, detainees, and illegal aliens), aeronautical research, or biological or geological resource management.
(iii) For the sole purpose of determining public aircraft status, qualified non-crewmember means an individual, other than a member of the crew, aboard an aircraft operated by the armed forces or an intelligence agency of the United States Government, or whose presence is required to perform, or is associated with the performance of, a governmental function.
(2) An aircraft owned or operated by the armed forces or chartered to provide transportation to the armed forces if—
(i) The aircraft is operated in accordance with title 10 of the United States Code;
(ii) The aircraft is operated in the performance of a governmental function under title 14, 31, 32, or 50 of the United States Code and the aircraft is not used for commercial purposes; or
(iii) The aircraft is chartered to provide transportation to the armed forces and the Secretary of Defense (or the Secretary of the department in which the Coast Guard is operating) designates the operation of the aircraft as being required in the national interest.
(3) An aircraft owned or operated by the National Guard of a State, the District of Columbia, or any territory or possession of the United States, and that meets the criteria of paragraph (2) of this definition, qualifies as a public aircraft only to the extent that it is operated under the direct control of the Department of Defense.
Published Instrument Approach Procedure Visual Segment
A segment on an IAP chart annotated as “Fly Visual to Airport” or ”Fly Visual.” A dashed arrow will indicate the visual flight path on the profile and plan view with an associated note on the approximate heading and distance. The visual segment should be flown as a dead reckoning course while maintaining visual conditions.
Published Route
A route for which an IFR altitude has been established and published; e.g., Federal Airways, Jet Routes, Area Navigation Routes, Specified Direct Routes.
Pulse
Pertaining to radar, a brief burst of electromagnetic radiation emitted by the radar; of very short time duration.
Pulse length
Pertaining to radar, the dimension of a radar pulse; may be expressed as the time duration or the length in linear units. Linear dimension is equal to time duration multiplied by the speed of propagation (approximately the speed of light).
Q Route
`Q’ is the designator assigned to published RNAV routes used by the United States.
Quadrant
A quarter part of a circle, centered on a NAVAID, oriented clockwise from magnetic north as follows: NE quadrant 000-089, SE quadrant 090-179, SW quadrant 180-269, NW quadrant 270-359.
Quasi-stationary front (commonly called stationary front)
A front which is stationary or nearly so; conventionally, a front which is moving at a speed of less than 5 knots is generally considered to be quasi-stationary.
Queuing
Staging/Queuing.
Quick Look
A feature of the EAS and ARTS which provides the controller the capability to display full data blocks of tracked aircraft from other control positions.
Rabbit, the
High-intensity flasher system installed at many large airports. The flashers consist of a series of brilliant blue-white bursts of light flashing in sequence along the approach lights, giving the effect of a ball of light traveling towards the runway.
Radar
Radio Detection And Ranging.
RADAR (contraction for radio detection and ranging)
An electronic instrument used for the detection and ranging of distant objects of such composition that they scatter or reflect radio energy. Since hydrometeors can scatter radio energy, weather radars, operating on certain frequency bands, can detect the presence of precipitation, clouds, or both.
Radar Advisory
The provision of advice and information based on radar observations.
Radar Altimeter
Radio Altimeter.
Radar altitude
The altitude of an aircraft determined by radar-type radio altimeter; thus the actual distance from the nearest terrain or water feature encompassed by the downward directed radar beam. For all practical purposes, it is the“actual” distance above a ground or inland water surface or the true altitude above an ocean surface.
Radar approach
The controller provides vectors while monitoring the progress of the flight with radar, guiding the pilot through the descent to the airport/heliport or to a specific runway.
Radar Approach Control Facility
A terminal ATC facility that uses radar and nonradar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility. a. Provides radar ATC services to aircraft operating in the vicinity of one or more civil and/or military airports in a terminal area. The facility may provide services of a ground controlled approach (GCA); i.e., ASR and PAR approaches. A radar approach control facility may be operated by FAA, USAF, US Army, USN, USMC, or jointly by FAA and a military service. Specific facility nomenclatures are used for administrative purposes only and are related to the physical location of the facility and the operating service generally as follows: 1. Army Radar Approach Control (ARAC) (Army). 2. Radar Air Traffic Control Facility (RATCF) (Navy/FAA). 3. Radar Approach Control (RAPCON) (Air Force/FAA). 4. Terminal Radar Approach Control (TRACON) (FAA). 5. Air Traffic Control Tower (ATCT) (FAA). (Only those towers delegated approach control authority.
Radar Approach [ICAO]
An approach, executed by an aircraft, under the direction of a radar controller.
Radar Arrival
An aircraft arriving at an airport served by a radar facility and in radar contact with the facility.
Radar Beacon
Radar.
Radar beam
The focused energy radiated by radar similar to a flashlight or searchlight beam.
Radar Clutter [ICAO]
The visual indication on a radar display of unwanted signals.
Radar Contact
A. Used by ATC to inform an aircraft that it is identified on the radar display and radar flight following will be provided until radar identification is terminated. Radar service may also be provided within the limits of necessity and capability. When a pilot is informed of “radar contact,” he/she automatically discontinues reporting over compulsory reporting points.
B. The term used to inform the controller that the aircraft is identified and approval is granted for the aircraft to enter the receiving controllers airspace.
Radar Contact Lost
Used by ATC to inform a pilot that radar data used to determine the aircraft’s position is no longer being received, or is no longer reliable and radar service is no longer being provided. The loss may be attributed to several factors including the aircraft merging with weather or ground clutter, the aircraft operating below radar line of sight coverage, the aircraft entering an area of poor radar return, failure of the aircraft transponder, or failure of the ground radar equipment.
Radar Contact [ICAO]
The situation which exists when the radar blip or radar position symbol of a particular aircraft is seen and identified on a radar display.
Radar Environment
An area in which radar service may be provided.
Radar Flight Following
The observation of the progress of radar identified aircraft, whose primary navigation is being provided by the pilot, wherein the controller retains and correlates the aircraft identity with the appropriate target or target symbol displayed on the radar scope.
Radar Identification
The process of ascertaining that an observed radar target is the radar return from a particular aircraft.
Radar Identification [ICAO]
The process of correlating a particular radar blip or radar position symbol with a specific aircraft.
Radar Identified Aircraft
An aircraft, the position of which has been correlated with an observed target or symbol on the radar display.
Radar Monitoring
Radar Service.
Radar Navigational Guidance
Radar Service.
Radar Point Out
An action taken by a controller to transfer the radar identification of an aircraft to another controller if the aircraft will or may enter the airspace or protected airspace of another controller and radio communications will not be transferred.
Radar Required
A term displayed on charts and approach plates and included in FDC NOTAMs to alert pilots that segments of either an instrument approach procedure or a route are not navigable because of either the absence or unusability of a NAVAID. The pilot can expect to be provided radar navigational guidance while transiting segments labeled with this term.
Radar Route
A flight path or route over which an aircraft is vectored. Navigational guidance and altitude assignments are provided by ATC.
Radar Separation
Radar Service.
Radar Service
A term which encompasses one or more of the following services based on the use of radar which can be provided by a controller to a pilot of a radar identified aircraft: Radar Monitoring, Radar Navigational Guidance, and Radar Separation.
Radar Service Terminated
Used by ATC to inform a pilot that he/she will no longer be provided any of the services that could be received while in radar contact. Radar service is automatically terminated, and the pilot is not advised in the following cases: a. An aircraft cancels its IFR flight plan, except within Class B airspace, Class C airspace, a TRSA, or where Basic Radar service is provided. b. An aircraft conducting an instrument, visual, or contact approach has landed or has been instructed to change to advisory frequency. c. An arriving VFR aircraft, receiving radar service to a tower-controlled airport within Class B airspace, Class C airspace, a TRSA, or where sequencing service is provided, has landed; or to all other airports, is instructed to change to tower or advisory frequency. d. An aircraft completes a radar approach.
Radar Service [ICAO]
Term used to indicate a service provided directly by means of radar. a. Monitoring The use of radar for the purpose of providing aircraft with information and advice relative to significant deviations from nominal flight path. b. Separation-The separation used when aircraft position information is derived from radar sources.
Radar services
Radar is a method whereby radio waves are transmitted into the air and are then received when they have been reflected by an object in the path of the beam. Range is determined by measuring the time it takes (at the speed of light) for the radio wave to go out to the object and then return to the receiving antenna. The direction of a detected object from a radar site is determined by the position of the rotating antenna when the reflected portion of the radio wave is received.
Radar summary chart
A weather product derived from the national radar network that graphically displays a summary of radar weather reports.
Radar Surveillance
The radar observation of a given geographical area for the purpose of performing some radar function.
Radar Traffic Advisories
Advisories issued to alert pilots to known or observed radar traffic which may affect the intended route of flight of their aircraft.
Radar Traffic Information Service
Traffic Advisories.
Radar Vectoring [ICAO]
Provision of navigational guidance to aircraft in the form of specific headings, based on the use of radar.
Radar weather report (SD)
A report issued by radar stations at 35 minutes after the hour, and special reports as needed. Provides information on the type, intensity, and location of the echo tops of the precipitation.
Radar [ICAO]
A radio detection device which provides information on range, azimuth and/or elevation of objects. a. Primary Radar-Radar system which uses reflected radio signals. b. Secondary Radar-Radar system wherein a radio signal transmitted from a radar station initiates the transmission of a radio signal from another station.
Radarsonde observation
A rawinsonde observation in which winds are determined by radar tracking a balloon-borne target.
Radial
A magnetic bearing extending from a VOR/VORTAC/TACAN navigation facility.
Radials
The courses oriented from a station.
Radiation
The emission of energy by a medium and transferred, either through free space or another medium, in the form of electromagnetic waves.
Radiation fog
Fog characteristically resulting when radiational cooling of the earth’s surface lowers the air temperature near the ground to or below its initial dew point on calm, clear nights.
Radio
A device used for communication.
Radio Altimeter
Aircraft equipment which makes use of the reflection of radio waves from the ground to determine the height of the aircraft above the surface.
Radio Beacon
Nondirectional Beacon.
Radio Detection And Ranging
Radar.
Radio frequency (RF)
A term that refers to alternating current (AC) having characteristics such that, if the current is input to antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications.
Radio Magnetic Indicator
An aircraft navigational instrument coupled with a gyro compass or similar compass that indicates the direction of a selected NAVAID and indicates bearing with respect to the heading of the aircraft.
Radio magnetic indicator (RMI)
An electronic navigation instrument that combines a magnetic compass with an ADF or VOR. The card of the RMI acts as a gyro-stabilized magnetic compass, and shows the magnetic heading the aircraft is flying.
Radio or radar altimeter
An electronic altimeter that determines the height of an aircraft above the terrain by measuring the time needed for a pulse of radio-frequency energy to travel from the aircraft to the ground and return.
Radio wave
An electromagnetic wave (EM wave) with frequency characteristics useful for radio transmission.
Radiosonde
A balloon-borne instrument for measuring pressure, temperature, and humidity aloft.
Radiosonde observation
A sounding made by the instrument.
Rain
A form of precipitation; drops are larger than drizzle and fall in relatively straight, although not necessarily vertical, paths as compared to drizzle which falls in irregular paths.
Rain shower
Precipitation from a cumuliform cloud; characterized by the suddenness of beginning and ending, by the rapid change of intensity, and usually by rapid change in the appearance of the sky; showery precipitation in the form of rain.
RAM recovery
The increase in thrust as a result of ram air pressures and density on the front of the engine caused by air velocity.
Ramp
Apron. A defined area on an airport or heliport intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, refueling, parking, or maintenance. With regard to seaplanes, a ramp is used for access to the apron from the water.
Ramp Weight
The total weight of the aircraft while on the ramp. It differs from takeoff weight by the weight of the fuel that will be consumed in taxiing to the point of takeoff.
Random Altitude
An altitude inappropriate for direction of flight and/or not in accordance with FAAO JO 7110.65, Para 4-5-1, VERTICAL SEPARATION MINIMA.
Random RNAV routes
Direct routes, based on area navigation capability, between waypoints defined in terms of latitude/longitude coordinates, degree-distance fixes, or offsets from established routes/airways at a specified distance and direction.
Random Route
Any route not established or charted/published or not otherwise available to all users.
Range attenuation
Reduction of radar power density because of distance from the antenna. It occurs in the outgoing beam at a rate proportional to 1/(range²) The return signal is also attenuated at the same rate.
Range resolution
The ability of radar to distinguish between targets on the same azimuth but at different ranges.
Range-height indicator (RHI) scope
A radar indicator scope displaying a vertical cross section of targets along a selected azimuth.
Ranging signals
Transmitted from the GPS satellite, these allow the aircrafts receiver to determine range (distance) from each satellite.
RAOB
A radiosonde observation.
Rapid decompression
The almost instantaneous loss of cabin pressure in aircraft with a pressurized cockpit or cabin.
Rate Of Turn
The rate in degrees/second of a turn.
Rated 2-minute OEI Power
With respect to rotorcraft turbine engines, the approved brake horsepower developed under static conditions at specified altitudes and temperatures within the operating limitations established for the engine under part 33 of this chapter, for continuation of one flight operation after the failure or shutdown of one engine in multiengine rotorcraft, for up to three periods of use no longer than 2 minutes each in any one flight, and followed by mandatory inspection and prescribed maintenance action.
Rated 21/2-minute OEI power
With respect to rotorcraft turbine engines, the approved brake horsepower developed under static conditions at specified altitudes and temperatures within the operating limitations established for the engine under part 33 of this chapter for periods of use no longer than 21/2minutes each after the failure or shutdown of one engine of a multiengine rotorcraft.
Rated 30-minute OEI power
With respect to rotorcraft turbine engines, the approved brake horsepower developed under static conditions at specified altitudes and temperatures within the operating limitations established for the engine under part 33 of this chapter, and limited in use to one period of use no longer than 30 minutes after the failure or shutdown of one engine of a multiengine rotorcraft.
Rated 30-second OEI Power
With respect to rotorcraft turbine engines, the approved brake horsepower developed under static conditions at specified altitudes and temperatures within the operating limitations established for the engine under part 33 of this chapter, for continuation of one flight operation after the failure or shutdown of one engine in multiengine rotorcraft, for up to three periods of use no longer than 30 seconds each in any one flight, and followed by mandatory inspection and prescribed maintenance action.
Rated continuous OEI power
With respect to rotorcraft turbine engines, the approved brake horsepower developed under static conditions at specified altitudes and temperatures within the operating limitations established for the engine under part 33 of this chapter, and limited in use to the time required to complete the flight after the failure or shutdown of one engine of a multiengine rotorcraft.
Rated maximum continuous augmented thrust
With respect to turbojet engine type certification, the approved jet thrust that is developed statically or in flight, in standard atmosphere at a specified altitude, with fluid injection or with the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and approved for unrestricted periods of use.
Rated maximum continuous power
With respect to reciprocating, turbopropeller, and turboshaft engines, the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.
Rated maximum continuous thrust
With respect to turbojet engine type certification, the approved jet thrust that is developed statically or in flight, in standard atmosphere at a specified altitude, without fluid injection and without the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and approved for unrestricted periods of use.
Rated takeoff augmented thrust
With respect to turbojet engine type certification, the approved jet thrust that is developed statically under standard sea level conditions, with fluid injection or with the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and limited in use to periods of not over 5 minutes for takeoff operation.
Rated takeoff power
With respect to reciprocating, turbopropeller, and turboshaft engine type certification, the approved brake horsepower that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.
Rated takeoff thrust
With respect to turbojet engine type certification, the approved jet thrust that is developed statically under standard sea level conditions, without fluid injection and without the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and limited in use to periods of not over 5 minutes for takeoff operation.
Rating
A statement that, as a part of a certificate, sets forth special conditions, privileges, or limitations.
Rawin
A rawinsonde observation.
Rawinsonde observation
A combined winds aloft and radiosonde observation. Winds are determined by tracking the radiosonde by radio direction finder or radar.
Read Back
Repeat my message back to me.
Readiness
A principle of learning where the eagerness and single-mindedness of a person toward learning affect the outcome of the learning experience.
Receiver
In communication, the listener, reader, or student who takes in a message containing information from a source, processes it, reacts with understanding, and changes behavior in accordance with the message.
Receiver autonomous integrity monitoring (RAIM)
A system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. This system is required for IFR-certified GPS units.
Receiver autonomous integrity monitoring (RAIM).
A system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. This system is required for IFR-certified GPS units.
Receiver-transmitter (RT)
A system that receives and transmits a signal and an indicator.
Receiving Controller
A controller/facility receiving control of an aircraft from another controller/facility.
Receiving Facility
Receiving Controller.
Recency
Principle of learning stating that things learned recently are remembered better than things learned some time ago. As time passes, less is remembered. Instructors use this principle when summarizing the important points at the end of a lecture in order for students to better remember them.
Reciprocating Engine
An engine that converts the heat energy from burning fuel into the reciprocating movement of the pistons. This movement is converted into a rotary motion by the connecting rods and crankshaft.
Recommended altitude
An altitude depicted on an instrument approach chart with the altitude value neither underscored nor overscored. The depicted value is an advisory value.
Reconformance
The automated process of bringing an aircraft’s Current Plan Trajectory into conformance with its track.
Record
See Database Record
Reduce Speed To (Speed)
Speed Adjustment.
Reduced vertical separation minimum (RVSM)
Reduces the vertical separation between flight level (FL) 290-410 from 2,000 feet to 1,000 feet and makes six additional FLs available for operation. Also see DRVSM.
Reduced Vertical Separation Minimums (RVSM)
RVSM airspace is where air traffic control separates aircraft by a minimum of 1,000 feet vertically between flight level (FL) 290 and FL 410 inclusive. RVSM airspace is special qualification airspace; the operator and the aircraft used by the operator must be approved by the Administrator. Air traffic control notifies operators of RVSM by providing route planing information.
Reduction Factor
A number, usually 100 or 1,000 by which a moment is divided to produce a smaller number that is less likely to cause mathematical errors when computing the center of gravity.
Reduction Gear
The gear arrangement in an aircraft engine that allows the engine to turn at a faster speed than the propeller.
Reference circle
The circle depicted in the plan view of an IAP chart that typically has a 10 NM radius, within which chart the elements are drawn to scale. (also, distance circle)
Reference circle (also, distance circle)
The circle depicted in the plan view of an IAP chart that typically has a 10 NM radius, within which chart the elements are drawn to scale.
Reference Datum
(GAMA) An imaginary vertical plane from which all horizontal distances are measured for balance purpose.
Reference landing speed
The speed of the airplane, in a specified landing configuration, at the point where it descends through the 50 foot height in the determination of the landing distance.
Reference Landing Speed (Vref)
The speed of the airplane, in a specified landing configuration, at the point where it descends through the 50-foot height in the determination of the landing distance.
Refraction
In radar, bending of the radar beam by variations in atmospheric density, water vapor content, and temperature.
Region Of Reverse Command
Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.
Regions of command
The regions of normal and reversed command refers to the relationship between speed and the power required to maintain or change that speed in flight.
Registration Certificate
A State and Federal certificate that documents aircraft ownership.
Relative bearing (RB)
The angular difference between the aircraft heading and the direction to the station, measured clockwise from the nose of the aircraft.
Relative bearing indicator (RBI)
Also known as the fixed- card ADF, zero is always indicated at the top of the instrument and the needle indicates the relative bearing to the station.
Relative humidity
The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature; usually expressed in percent.
Relative vorticity
Vorticity of the air relative to the Earth, disregarding the component of vorticity resulting from Earth’s rotation.
Relative Wind
The direction of the airflow with respect to the wing. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flightpath of the airplane.
Relay question
Used in response to a student’s question, the student question is redirected to another student.
Release Time
A departure time restriction issued to a pilot by ATC (either directly or through an authorized relay) when necessary to separate a departing aircraft from other traffic.
Release Time [ICAO]
Time prior to which an aircraft should be given further clearance or prior to which it should not proceed in case of radio failure.
Reliability
The degree to which test results are consistent with repeated measurements.
Remote Airport Advisory (RAA)
A remote service which may be provided by facilities, which are not located on the landing airport, but have a discrete ground-to-air communication frequency or tower frequency when the tower is closed, automated weather reporting with voice available to the pilot at the landing airport, and a continuous ASOS/AWSS/AWOS data display, other direct reading instruments, or manual observation is available to the AFSS specialist.
Remote Airport Information Service (RAIS)
A temporary service provided by facilities, which are not located on the landing airport, but have communication capability and automated weather reporting available to the pilot at the landing airport.
Remote Communications Air/Ground Facility
An unmanned VHF/UHF transmitter/receiver facility which is used to expand ARTCC air/ground communications coverage and to facilitate direct contact between pilots and controllers. RCAG facilities are sometimes not equipped with emergency frequencies 121.5 MHz and 243.0 MHz.
Remote Communications Outlet
An unmanned communications facility remotely controlled by air traffic personnel. RCOs serve FSSs. RTRs serve terminal ATC facilities. An RCO or RTR may be UHF or VHF and will extend the communication range of the air traffic facility. There are several classes of RCOs and RTRs. The class is determined by the number of transmitters or receivers. Classes A through G are used primarily for air/ground purposes. RCO and RTR class O facilities are nonprotected outlets subject to undetected and prolonged outages. RCO (O’s) and RTR (O’s) were established for the express purpose of providing ground-to-ground communications between air traffic control specialists and pilots located at a satellite airport for delivering en route clearances, issuing departure authorizations, and acknowledging instrument flight rules cancellations or departure/landing times. As a secondary function, they may be used for advisory purposes whenever the aircraft is below the coverage of the primary air/ground frequency.
Remote Communications Outlet (RCO)
An unmanned communications facility remotely controlled by air traffic personnel. RCOs serve FSSs and may be UHF or VHF. RCOs extend the communication range of the air traffic facility. RCOs were established to provide ground-to-ground communications between air traffic control specialists and pilots located at a satellite airport for delivering en route clearances, issuing departure authorizations, and acknowledging IFR cancellations or departure/landing times.
Remote scope
In radar meteorology a “slave” scope remoted from weather radar.
Remote Transmitter/Receiver
Remote Communications Outlet.
Report
Used to instruct pilots to advise ATC of specified information; e.g., “Report passing Hamilton VOR.”
Reporting Point
A geographical location in relation to which the position of an aircraft is reported. (See Compulsory Reporting Points)
Reporting Point [ICAO]
A specified geographical location in relation to which the position of an aircraft can be reported.
Repression
Theory of forgetting proposing that a person is more likely to forget information which is unpleasant or produces anxiety.
Request Full Route Clearance
Used by pilots to request that the entire route of flight be read verbatim in an ATC clearance. Such request should be made to preclude receiving an ATC clearance based on the original filed flight plan when a filed IFR flight plan has been revised by the pilot, company, or operations prior to departure.
Required Navigation Performance (RNP)
RNP is a statement of the navigation performance necessary for operation within a defined airspace. On-board monitoring and alerting is required.
Required Navigation Performance (RNP) Airspace
A generic term designating airspace, route (s), leg (s), operation (s), or procedure (s) where minimum required navigational performance (RNP) have been established.
Required Navigation Performance Level Or Type (RNP-X)
A value, in nautical miles (NM), from the intended horizontal position within which an aircraft would be at least 95-percent of the total flying time.
Rescue Co-Ordination Centre [ICAO]
A unit responsible for promoting efficient organization of search and rescue service and for coordinating the conduct of search and rescue operations within a search and rescue region.
Rescue Coordination Center
A search and rescue (SAR) facility equipped and manned to coordinate and control SAR operations in an area designated by the SAR plan. The U.S. Coast Guard and the U.S. Air Force have responsibility for the operation of RCCs.
Residual Fuel
Fuel that remains trapped in the system after draining the fuel from the aircraft with the aircraft in level flight attitude. The weight of this residual fuel is counted as part of the empty weight of the aircraft.
Resolution
Pertaining to radar, the ability of radar to show discrete targets separately, i.e., the better the resolution, the closer two targets can be to each other, and still be detected as separate targets.
Resolution Advisory
A display indication given to the pilot by the traffic alert and collision avoidance systems (TCAS II) recommending a maneuver to increase vertical separation relative to an intruding aircraft. Positive, negative, and vertical speed limit (VSL) advisories constitute the resolution advisories. A resolution advisory is also classified as corrective or preventive
Response
Possible answer to a multiple-choice test item. The correct response is often called the keyed response, and incorrect responses are called distractors.
Restricted area
Airspace designated under 14 CFR part 73 within which the flight of aircraft, while not wholly prohibited, is subject to restriction.
Restricted Area [ICAO]
An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is restricted in accordance with certain specified conditions.
Resume Normal Speed
Used by ATC to advise a pilot that previously issued speed control restrictions are deleted. An instruction to “resume normal speed” does not delete speed restrictions that are applicable to published procedures of upcoming segments of flight, unless specifically stated by ATC. This does not relieve the pilot of those speed restrictions which are applicable to 14 CFR Section 91.117.
Resume Own Navigation
Used by ATC to advise a pilot to resume his/her own navigational responsibility. It is issued after completion of a radar vector or when radar contact is lost while the aircraft is being radar vectored.
Reverse question
Used in response to a student’s question. Rather than give a direct answer to the student’s query, the instructor returns the question to the same student to provide the answer.
Reverse sensing
The VOR needle appearing to indicate the reverse of normal operation.
Reverse Thrust
A condition where jet thrust is directed forward during landing to increase the rate of deceleration.
Reversing Propeller
A propeller system with a pitch change mechanism that includes full reversing capability. When the pilot moves the throttle controls to reverse, the blade angle changes to a pitch angle and produces a reverse thrust, which slows the airplane down during a landing.
Review and evaluation
The fourth and last step in the teaching process, which consists of a review of all material and an evaluation of the students. In the telling and doing technique of flight instruction, this step consists of the instructor evaluating the student’s performance while the student performs the required procedure.
Rhetorical question
Generally, a question asked for a purpose other than to obtain the information the question asks. For this handbook’s purpose, a question asked to stimulate group thought. Normally answered by the instructor, it is more commonly used in lecturing rather than in guided discussions.
Rhodopsin
The photosensitive pigments that initiate the visual response in the rods of the eye.
Ridge (also called ridge line)
In meteorology, an elongated area of relatively high atmospheric pressure; usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow (isobars, contours, or streamlines).
Rigging
The final adjustment and alignment of an aircraft and its flight control system that provides the proper aerodynamic characteristics.
Right Base Area
A type of Terminal Arrival Area. A 30NM arc centered on the left corner IAF (Initial Approach Fix). The area shares a boundary with the straight-in area except that it extends out for 30NM from the IAF and is bounded on the other side by a line extending from the IF through the FAF to the arc.
Rigidity
The characteristic of a gyroscope that prevents its axis of rotation tilting as the Earth rotates.
Rigidity in space
The principle that a wheel with a heavily weighted rim spinning rapidly will remain in a fixed position in the plane in which it is spinning.
Rime ice
Rough, milky, opaque ice formed by the instantaneous freezing of small supercooled water droplets.
Rime icing (or rime ice)
The formation of a white or milky and opaque granular deposit of ice formed by the rapid freezing of supercooled water droplets as they impinge upon an exposed aircraft.
Risk
The future impact of a hazard that is not eliminated or controlled.
Risk elements
There are four fundamental risk elements in aviation: the pilot, the aircraft, the environment, and the type of operation that comprise any given aviation situation.
Risk elements in ADM
Take into consideration the four fundamental risk elements: the pilot, the aircraft, the environment, and external pressures.
Risk management
The part of the decision-making process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated with each flight.
RNAV Approach
An instrument approach procedure which relies on aircraft area navigation equipment for navigational guidance.
RNAV Specification
A navigation specification based on area navigation that does not include the requirement for performance monitoring and alerting, designated by the prefix RNAV; e.g., RNAV 5, RNAV 1.
RNP Specification
A navigation specification based on area navigation that includes the requirement for performance monitoring and alerting, designated by the prefix RNP; e.g., RNP 4, RNP APCH.
Road Reconnaissance
Military activity requiring navigation along roads, railroads, and rivers. Reconnaissance route/route segments are seldom along a straight line and normally require a lateral route width of 10 NM to 30 NM and an altitude range of 500 feet to 10,000 feet AGL.
Rocket
An aircraft propelled by ejected expanding gases generated in the engine from self-contained propellants and not dependent on the intake of outside substances. It includes any part which becomes separated during the operation.
Rocketsonde
A type of radiosonde launched by a rocket and making its measurements during a parachute descent; capable of obtaining soundings to a much greater height than possible by balloon or aircraft.
Roger
I have received all of your last transmission. It should not be used to answer a question requiring a yes or a no answer.
Roll
The motion of the aircraft about the longitudinal axis. It is controlled by the ailerons.
Roll cloud
A dense and horizontal roll-shaped accessory cloud located on the lower leading edge of a cumulonimbus or less often, a rapidly developing cumulus; indicative of turbulence. Sometimes improperly called rotor cloud.
Roll-out RVR
The RVR readout values obtained from sensors located nearest the rollout end of the runway.
Rollout RVR
The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway.
Rote learning
A basic level of learning in which the student has the ability to repeat back something learned, with no understanding or ability to apply what was learned.
Rotor cloud
A turbulent cloud formation found in the lee of some large mountain barriers, the air in the cloud rotates around an axis parallel to the range; indicative of possible violent turbulence. Sometimes improperly called roll cloud.
Rotorcraft
A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors.
Rotorcraft-load combination
The combination of a rotorcraft and an external-load, including the external-load attaching means. Rotorcraft-load combinations are designated as Class A, Class B, Class C, and Class D, as follows:
(1) Class A rotorcraft-load combination means one in which the external load cannot move freely, cannot be jettisoned, and does not extend below the landing gear.
(2) Class B rotorcraft-load combination means one in which the external load is jettisonable and is lifted free of land or water during the rotorcraft operation.
(3) Class C rotorcraft-load combination means one in which the external load is jettisonable and remains in contact with land or water during the rotorcraft operation.
(4) Class D rotorcraft-load combination means one in which the external-load is other than a Class A, B, or C and has been specifically approved by the Administrator for that operation.
Roundout (Flare)
A pitch-up during landing approach to reduce rate of descent and forward speed prior to touchdown.
Route
A defined path, consisting of one or more courses in a horizontal plane, which aircraft traverse over the surface of the earth.
Route Action Notification
URET notification that a PAR/PDR/PDAR has been applied to the flight plan.
Route segment
A portion of a route bounded on each end by a fix or navigation aid (NAVAID).
Route Segment [ICAO]
A portion of a route to be flown, as defined by two consecutive significant points specified in a flight plan.
Rudder
The movable primary control surface mounted on the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis.
Ruddervator
A pair of control surfaces on the tail of an aircraft arranged in the form of a V. These surfaces, when moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve as a rudder.
Runback Ice
Ice that forms from the freezing or refreezing of water leaving protected surfaces and running back to unprotected surfaces.
Runway
A defined rectangular area on a land airport prepared for the landing and takeoff run of aircraft along its length. Runways are normally numbered in relation to their magnetic direction rounded off to the nearest 10 degrees; e.g., Runway 1, Runway 25.
Runway Centerline Lighting
Flush centerline lights spaced at 50-foot intervals beginning 75 feet from the landing threshold and extending to within 75 feet of the opposite end of the runway.
Runway Centerline Lights
Runway centerline lights are installed on some precision approach runways to facilitate landing under adverse visibility conditions. They are located along the runway centerline and are spaced at 50-foot intervals. When viewed from the landing threshold, the runway centerline lights are white until the last 3,000 feet of the runway. The white lights begin to alternate with red for the next 2,000 feet, and for the last 1,000 feet of the runway, all centerline lights are red.
Runway Centerline Markings
The runway centerline identifies the center of the runway and provides alignment guidance during takeoff and landings. The centerline consists of a line of uniformly spaced stripes and gaps.
Runway Condition Reading
Numerical decelerometer readings relayed by air traffic controllers at USAF and certain civil bases for use by the pilot in determining runway braking action. These readings are routinely relayed only to USAF and Air National Guard Aircraft.
Runway Edge Lights
Runway edge lights are used to outline the edges of runways during periods of darkness or restricted visibility conditions. These light systems are classified according to the intensity or brightness they are capable of producing: they are the High Intensity Runway Lights (HIRL), Medium Intensity Runway Lights (MIRL), and the Low Intensity Runway Lights (LIRL). The HIRL and MIRL systems have variable intensity controls, whereas the LIRLs normally have one intensity setting.
Runway End Identifier Lights (REIL)
One component of the runway lighting system. These lights are installed at many airfields to provide rapid and positive identification of the approach end of a particular runway.
Runway Gradient
The average slope, measured in percent, between two ends or points on a runway. Runway gradient is depicted on Government aerodrome sketches when total runway gradient exceeds 0.3%.
Runway Heading
The magnetic direction that corresponds with the runway centerline extended, not the painted runway numbers on the runway. Pilots cleared to “fly or maintain runway heading” are expected to fly or maintain the published heading that corresponds with the extended centerline of the departure runway (until otherwise instructed by ATC), and are not to apply drift correction; e.g., RWY 4, actual magnetic heading of the runway centerline 044.22°, fly 044°.
Runway Hotspots
Locations on a particular airport that historically have hazardous intersections. Hot spots alert pilots to the fact that there may be a lack of visibility at certain points or the tower may be unable to see that particular intersection. Whatever the reason, pilots need to be aware that these hazardous intersections exist and they should be increasingly vigilant when approaching and taxiing through these intersections. Pilots are typically notified of these areas by a Letter to Airmen or by accessing the FAA Office of Runway Safety.
Runway In Use/Active Runway/Duty Runway
Any runway or runways currently being used for takeoff or landing. When multiple runways are used, they are all considered active runways. In the metering sense, a selectable adapted item which specifies the landing runway configuration or direction of traffic flow. The adapted optimum flight plan from each transition fix to the vertex is determined by the runway configuration for arrival metering processing purposes.
Runway Incursion
An occurrence at an airport involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in a loss of separation with an aircraft that is taking off, intending to take off, landing, or intending to land.
Runway Lights/Runway Edge Lights
Lights having a prescribed angle of emission used to define the lateral limits of a runway. Runway lights are uniformly spaced at intervals of approximately 200 feet, and the intensity may be controlled or preset.
Runway Markings
Airport Marking Aids. Markings used on runway and taxiway surfaces to identify a specific runway, a runway threshold, a centerline, a hold line, etc. A runway should be marked in accordance with its present usage such as: a. Visual. b. Nonprecision instrument. c. Precision instrument.
Runway OFZ
The runway OFZ (Obstacle Free Zone) is a defined volume of airspace centered above the runway. The runway OFZ is the airspace above a surface whose elevation at any point is the same as the elevation of the nearest point on the runway centerline. The runway OFZ extends 200 feet beyond each end of the runway. The width is as follows: 1. For runways serving large airplanes, the greater of: (a) 400 feet, or (b) 180 feet, plus the wingspan of the most demanding airplane, plus 20 feet per 1,000 feet of airport elevation. 2. For runways serving only small airplanes: (a) 300 feet for precision instrument runways. (b) 250 feet for other runways serving small airplanes with approach speeds of 50 knots, or more. (c) 120 feet for other runways serving small airplanes with approach speeds of less than 50 knots.
Runway Overrun
In military aviation exclusively, a stabilized or paved area beyond the end of a runway, of the same width as the runway plus shoulders, centered on the extended runway centerline.
Runway Profile Descent
An instrument flight rules (IFR) air traffic control arrival procedure to a runway published for pilot use in graphic and/or textual form and may be associated with a STAR. Runway Profile Descents provide routing and may depict crossing altitudes, speed restrictions, and headings to be flown from the en route structure to the point where the pilot will receive clearance for and execute an instrument approach procedure. A Runway Profile Descent may apply to more than one runway if so stated on the chart.
Runway Safety Area
A defined surface surrounding the runway prepared, or suitable, for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway. The dimensions of the RSA vary and can be determined by using the criteria contained within AC 150/5300-13, Airport Design, Chapter 3. Figure 3-1 in AC 150/5300-13 depicts the RSA. The design standards dictate that the RSA shall be: a. Cleared, graded, and have no potentially hazardous ruts, humps, depressions, or other surface variations; b. Drained by grading or storm sewers to prevent water accumulation; c. Capable, under dry conditions, of supporting snow removal equipment, aircraft rescue and firefighting equipment, and the occasional passage of aircraft without causing structural damage to the aircraft; and, d. Free of objects, except for objects that need to be located in the runway safety area because of their function. These objects shall be constructed on low impact resistant supports (frangible mounted structures) to the lowest practical height with the frangible point no higher than 3 inches above grade.
Runway Safety Program (RSP)
Designed to create and execute a plan of action that reduces the number of runway incursions at the nations airports.
Runway temperature
The temperature of the air just above a runway, ideally at engine and/or wing height, used in the determination of density altitude; useful at airports when critical values of density altitude prevail.
Runway Threshold Markings
Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline, or the number of stripes is related to the runway width. A threshold marking helps identify the beginning of the runway that is available for landing. In some instances, the landing threshold may be displaced.
Runway Transition
A. Conventional STARs/SIDs. The portion of a STAR/SID that serves a particular runway or runways at an airport.
B. RNAV STARs/SIDs. Defines a path(s) from the common route to the final point(s) on a STAR. For a SID, the common route that serves a particular runway or runways at an airport.
Runway Use Program
A noise abatement runway selection plan designed to enhance noise abatement efforts with regard to airport communities for arriving and departing aircraft. These plans are developed into runway use programs and apply to all turbojet aircraft 12,500 pounds or heavier; turbojet aircraft less than 12,500 pounds are included only if the airport proprietor determines that the aircraft creates a noise problem. Runway use programs are coordinated with FAA offices, and safety criteria used in these programs are developed by the Office of Flight Operations. Runway use programs are administered by the Air Traffic Service as “Formal” or “Informal” programs.
Runway visibility
The meteorological visibility along an identified runway determined from a specified point on the runway; may be determined by a transmissometer or by an observer.
Runway Visibility Value
Visibility.
Runway Visibility Value (RVV)
The visibility determined for a particular runway by a transmissometer. A meter provides a continuous indication of the visibility (reported in miles or fractions of miles) for the runway. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway.
Runway visual range
An instrumentally derived horizontal distance a pilot should see down the runway from the approach end; based on either the sighting of high intensity runway lights or on the visual contrast of other objects, whichever yields the greatest visual range.
Runway Visual Range (RVR)
An estimate of the maximum distance at which the runway, or the specified lights or markers delineating it, can be seen from a position above a specific point on the runway centerline. RVR is normally determined by visibility sensors or transmissometers located alongside and higher than the centerline of the runway. RVR is reported in hundreds of feet.
Runway Visual Range [RVR] [ICAO]
The range over which the pilot of an aircraft on the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.
Runway [ICAO]
A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft.
Safety (Squat) Switch
An electrical switch mounted on one of the landing gear struts. It is used to sense when the weight of the aircraft is on the wheels.
Safety Alert
A safety alert issued by ATC to aircraft under their control if ATC is aware the aircraft is at an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to terrain, obstructions, or other aircraft. The controller may discontinue the issuance of further alerts if the pilot advises he/she is taking action to correct the situation or has the other aircraft in sight. Note: The issuance of a safety alert is contingent upon the capability of the controller to have an awareness of an unsafe condition. The course of action provided will be predicated on other traffic under ATC control. Once the alert is issued, it is solely the pilot’s prerogative to determine what course of action, if any, he/she will take.
Safety Logic System
A software enhancement to ASDE-3, ASDE-X, and ASDE-3X, that predicts the path of aircraft landing and/or departing, and/or vehicular movements on runways. Visual and aural alarms are activated when the safety logic projects a potential collision. The Airport Movement Area Safety System (AMASS) is a safety logic system enhancement to the ASDE-3. The Safety Logic System for ASDE-X and ASDE-3X is an integral part of the software program.
Safety Logic System Alerts
Types include: Alert, False Alert, Nuisance Alert, Valid Non-Alert, and Invalid Non-Alert.
Sail Back
A maneuver during high wind conditions (usually with power off) where float plane movement is controlled by water rudders/opening and closing cabin doors.
Same Direction Aircraft
Aircraft are operating in the same direction when: a. They are following the same track in the same direction; or b. Their tracks are parallel and the aircraft are flying in the same direction; or c. Their tracks intersect at an angle of less than 45 degrees.
Santa Ana
A hot, dry, foehn wind, generally from the northeast or east, occurring west of the Sierra Nevada Mountains especially in the pass and river valley near Santa Ana, California.
Satellite ephemeris data
Data broadcast by the GPS satellite containing very accurate orbital data for that satellite, atmospheric propagation data, and satellite clock error data.
Saturated adiabatic lapse rate
The rate of decrease of temperature with height as saturated air is lifted with no gain or loss of heat from outside sources; varies with temperature, being greatest at low temperatures.
Saturation
The condition of the atmosphere when actual water vapor present is the maximum possible at existing temperature.
Say Again
Used to request a repeat of the last transmission. Usually specifies transmission or portion thereof not understood or received; e.g., “Say again all after ABRAM VOR.”
Say Altitude
Used by ATC to ascertain an aircraft’s specific altitude/flight level. When the aircraft is climbing or descending, the pilot should state the indicated altitude rounded to the nearest 100 feet.
Say Heading
Used by ATC to request an aircraft heading. The pilot should state the actual heading of the aircraft.
Scan
A procedure used by the pilot to visually identify all resources of information in flight.
Scenario-based training (SBT)
Training method that uses a highly structured script of real world experiences to address aviation training objectives in an operational environment.
Scheduled Time Of Arrival (STA)
A STA is the desired time that an aircraft should cross a certain point (landing or metering fix). It takes other traffic and airspace configuration into account. A STA time shows the results of the TMA scheduler that has calculated an arrival time according to parameters such as optimized spacing, aircraft performance, and weather.
Scud
Small detached masses of stratus fractus clouds below a layer of higher clouds, usually nimbostratus.
Sea breeze
A coastal breeze blowing from sea to land, caused by the temperature difference when the land surface is warmer than the sea surface. Compare land breeze.
Sea fog
A type of advection fog formed when air that has been lying over a warm surface is transported over a colder water surface.
Sea Lane
A designated portion of water outlined by visual surface markers for and intended to be used by aircraft designed to operate on water.
Sea Level
A reference height used to determine standard atmospheric conditions and altitude measurements.
Sea level engine
A reciprocating aircraft engine having a rated takeoff power that is producible only at sea level.
Sea level pressure
The atmospheric pressure at mean sea level, either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level; used as a common reference for analyses of surface pressure patterns.
Sea smoke
Same as steam fog—fog formed when cold air moves over relatively warm water or wet ground.
Search And Rescue
A service which seeks missing aircraft and assists those found to be in need of assistance. It is a cooperative effort using the facilities and services of available Federal, state and local agencies. The U.S. Coast Guard is responsible for coordination of search and rescue for the Maritime Region, and the U.S. Air Force is responsible for search and rescue for the Inland Region. Information pertinent to search and rescue should be passed through any air traffic facility or be transmitted directly to the Rescue Coordination Center by telephone.
Search And Rescue Facility
A facility responsible for maintaining and operating a search and rescue (SAR) service to render aid to persons and property in distress. It is any SAR unit, station, NET, or other operational activity which can be usefully employed during an SAR Mission; e.g., a Civil Air Patrol Wing, or a Coast Guard Station.
Second in command
A pilot who is designated to be second in command of an aircraft during flight time.
Secondary Radar Target
A target derived from a transponder return presented on a radar display.
Secondary Radar/Radar Beacon (ATCRBS)
A radar system in which the object to be detected is fitted with cooperative equipment in the form of a radio receiver/transmitter (transponder). Radar pulses transmitted from the searching transmitter/receiver (interrogator) site are received in the cooperative equipment and used to trigger a distinctive transmission from the transponder. This reply transmission, rather than a reflected signal, is then received back at the transmitter/receiver site for processing and display at an air traffic control facility.
Sectional aeronautical charts
Designed for visual navigation of slow- or medium-speed aircraft. Topographic information on these charts features the portrayal of relief, and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.
Sectional Aeronautical Charts (1:500,000)
Designed for visual navigation of slow or medium speed aircraft. Topographic information on these charts features the portrayal of relief and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
Sector List Drop Interval
A parameter number of minutes after the meter fix time when arrival aircraft will be deleted from the arrival sector list.
Sector visibility
Meteorological visibility within a specified sector of the horizon circle.
Security Notice (SECNOT)
A SECNOT is a request originated by the Air Traffic Security Coordinator (ATSC) for an extensive communications search for aircraft involved, or suspected of being involved, in a security violation. A SECNOT will include the aircraft identification, search area, and expiration time. The search area, as defined by the ATSC, could be a single airport, multiple airports, a radius of an airport or fix, or a route of flight. Once the expiration time has been reached, the SECNOT is considered to be cancelled.
Security Services Airspace
Areas established through the regulatory process or by NOTAM, issued by the Administrator under title 14, CFR, sections 99.7, 91.141, and 91.139, which specify that ATC security services are required; i.e., ADIZ or temporary flight rules areas.
See And Avoid
When weather conditions permit, pilots operating IFR or VFR are required to observe and maneuver to avoid other aircraft. Right-of-way rules are contained in 14 CFR Part 91.
Segmented Circle
A visual ground based structure to provide traffic pattern information.
Segments Of An Instrument Approach Procedure
An instrument approach procedure may have as many as four separate segments depending on how the approach procedure is structured. Initial Approach, Intermediate Approach, Final Approach, and Missed Approach.
Selection-type test items
Test items requiring the student to choose from two or more alternatives provided. True-false, matching, and multiple-choice type questions are examples of selection type test items.
Selective availability (SA)
A satellite technology permitting the Department of Defense (DOD) to create, in the interest of national security, a significant clock and ephemeris error in the satellites, resulting in a navigation error.
Self-concept
A perception factor that ties together how people feel about themselves with how well they receive experiences.
Semicircular canal
An inner ear organ that detects angular acceleration of the body.
Semimonocoque
A fuselage design that includes a substructure of bulkheads and/or formers, along with stringers, to support flight loads and stresses imposed on the fuselage.
Sensitive altimeter
A form of multipointer pneumatic altimeter with an adjustable barometric scale that allows the reference pressure to be set to any desired level.
Sensitivity time control
A radar circuit designed to correct for range attenuation so that echo intensity on the scope is proportional to reflectivity of the target regardless of range.
Sensory register
That portion of the brain which receives input from the five senses. The individual’s preconceived concept of what is important determines how the register prioritizes the information for passing it on to the rest of the brain for action.
Separation
In air traffic control, the spacing of aircraft to achieve their safe and orderly movement in flight and while landing and taking off.
Separation Minima
The minimum longitudinal, lateral, or vertical distances by which aircraft are spaced through the application of air traffic control procedures.
Separation [ICAO]
Spacing between aircraft, levels or tracks.
Service
A generic term that designates functions or assistance available from or rendered by air traffic control. For example, Class C service would denote the ATC services provided within a Class C airspace area.
Service Ceiling
The maximum density altitude where the best rate-of-climb airspeed will produce a 100 feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.
Servo
A motor or other form of actuator which receives a small signal from the control device and exerts a large force to accomplish the desired work.
Servo Tab
An auxiliary control mounted on a primary control surface, which automatically moves in the direction opposite the primary control to provide an aerodynamic assist in the movement of the control.
Severe Icing
The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary.
Severe Weather Avoidance Plan
An approved plan to minimize the affect of severe weather on traffic flows in impacted terminal and/or ARTCC areas. SWAP is normally implemented to provide the least disruption to the ATC system when flight through portions of airspace is difficult or impossible due to severe weather.
Severe Weather Forecast Alerts
Preliminary messages issued in order to alert users that a Severe Weather Watch Bulletin (WW) is being issued. These messages define areas of possible severe thunderstorms or tornado activity. The messages are unscheduled and issued as required by the Storm Prediction Center (SPC) at Norman, Oklahoma.
Shaft Horse Power (SHP)
Turboshaft engines are rated in shaft horsepower and calculated by use of a dynamometer device. Shaft horsepower is exhaust thrust converted to a rotating shaft.
Shear
Wind shear. The rate of change of wind velocity (direction and/or speed) per unit distance; conventionally expressed as vertical or horizontal wind shear.
Shock Waves
A compression wave formed when a body moves through the air at a speed greater than the speed of sound.
Short Range Clearance
A clearance issued to a departing IFR flight which authorizes IFR flight to a specific fix short of the destination while air traffic control facilities are coordinating and obtaining the complete clearance.
Short Takeoff And Landing Aircraft
An aircraft which, at some weight within its approved operating weight, is capable of operating from a runway in compliance with the applicable STOL characteristics, airworthiness, operations, noise, and pollution standards.
Show
Unless the context otherwise requires, to show to the satisfaction of the Administrator.
Shower
Precipitation from a cumuliform cloud; characterized by the suddenness of beginning and ending, by the rapid change of intensity, and usually by rapid change in the appearance of the sky; showery precipitation may be in the form of rain, ice pellets, or snow.
Sideslip
A slip in which the airplane’s longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight ahead. Instead, the horizontal component of wing lift forces the airplane to move sideways toward the low wing.
Sidestep Maneuver
A visual maneuver accomplished by a pilot at the completion of an instrument approach to permit a straight-in landing on a parallel runway not more than 1,200 feet to either side of the runway to which the instrument approach was conducted.
SIGMET Information [ICAO]
Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations.
Signal-to-noise ratio
An indication of signal strength received compared to background noise, which is a measure of how adequate the received signal is.
Significant Meteorological Information
SIGMET.
Significant Meteorological Information (SIGMET)
Information about in-flight weather of operational significance to the safety of all aircraft. SIGMETs may include severe icing. (See CWA and AIRMET.)
Significant Point
[ICAO Annex 11] A specified geographical location used in defining an ATS route or the flight path of an aircraft and for other navigation and ATS purposes.
Significant weather prognostic
Presents four panels showing forecast significant weather.
Simplex
Transmission and reception on the same frequency.
Simplified Directional Facility
A NAVAID used for nonprecision instrument approaches. The final approach course is similar to that of an ILS localizer except that the SDF course may be offset from the runway, generally not more than 3 degrees, and the course may be wider than the localizer, resulting in a lower degree of accuracy.
Simplified directional facility (SDF)
A NAVAID used for nonprecision instrument approaches. The final approach course is similar to that of an ILS localizer; however, the SDF course may be offset from the runway, generally not more than 3°, and the course may be wider than the localizer, resulting in a lower degree of accuracy.
Simulated Flameout
A practice approach by a jet aircraft (normally military) at idle thrust to a runway. The approach may start at a runway (high key) and may continue on a relatively high and wide downwind leg with a continuous turn to final. It terminates in landing or low approach. The purpose of this approach is to simulate a flameout.
Simultaneous ILS Approaches
An approach system permitting simultaneous ILS/MLS approaches to airports having parallel runways separated by at least 4,300 feet between centerlines. Integral parts of a total system are ILS/MLS, radar, communications, ATC procedures, and appropriate airborne equipment.
Simultaneous MLS Approaches
An approach system permitting simultaneous ILS/MLS approaches to airports having parallel runways separated by at least 4,300 feet between centerlines. Integral parts of a total system are ILS/MLS, radar, communications, ATC procedures, and appropriate airborne equipment.
Single Direction Routes
Preferred IFR Routes which are sometimes depicted on high altitude en route charts and which are normally flown in one direction only.
Single Engine Absolute Ceiling
The altitude that a twin-engine airplane can no longer climb with one engine inoperative.
Single Engine Service Ceiling
The altitude that a twin-engine airplane can no longer climb at a rate greater then 50 f.p.m. with one engine inoperative.
Single Frequency Approach
A service provided under a letter of agreement to military single-piloted turbojet aircraft which permits use of a single UHF frequency during approach for landing. Pilots will not normally be required to change frequency from the beginning of the approach to touchdown except that pilots conducting an en route descent are required to change frequency when control is transferred from the air route traffic control center to the terminal facility. The abbreviation “SFA” in the DOD FLIP IFR Supplement under “Communications” indicates this service is available at an aerodrome.
Single-pilot resource management (SRM)
The ability for crew or pilot to manage all resources effectively to ensure the outcome of the flight is successful.
Single-Piloted Aircraft
A military turbojet aircraft possessing one set of flight controls, tandem cockpits, or two sets of flight controls but operated by one pilot is considered single-piloted by ATC when determining the appropriate air traffic service to be applied.
Sites
Internet addresses which provide information and often are linked to other similar sites.
Situational awareness
Pilot knowledge of where the aircraft is in regard to location, air traffic control, weather, regulations, aircraft status, and other factors that may affect flight.
Skid
A condition where the tail of the airplane follows a path outside the path of the nose during a turn.
Skidding turn
An uncoordinated turn in which the rate of turn is too great for the angle of bank, pulling the aircraft to the outside of the turn.
Skill knowledge
Knowledge reflected in motor or manual skills and in cognitive or mental skills that manifests itself in the doing of something.
Skills and procedures
The procedural, psychomotor, and perceptual skills used to control a specific aircraft or its systems. They are the stick and rudder or airmanship abilities that are gained through conventional training, are perfected, and become almost automatic through experience.
Skin friction drag
Drag generated between air molecules and the solid surface of the aircraft.
Skyspotter
A pilot who has received specialized training in observing and reporting inflight weather phenomena.
Slant range
The horizontal distance from the aircraft antenna to the ground station, due to line-of-sight transmission of the DME signal.
Slant visibility
For an airborne observer, the distance at which he can see and distinguish objects on the ground.
Slash
A radar beacon reply displayed as an elongated target.
Slaved compass
A system whereby the heading gyro is slaved to, or continuously corrected to bring its direction readings into agreement with a remotely located magnetic direction sensing device (usually this is a flux valve or flux gate compass).
Sleet
Ice pellets mixed with rain or snow.
Slip
An intentional maneuver to decrease airspeed or increase rate of descent, and to compensate for a crosswind on landing. A slip can also be unintentional when the pilot fails to maintain the aircraft in coordinated flight.
Slipping turn
An uncoordinated turn in which the aircraft is banked too much for the rate of turn, so the horizontal lift component is greater than the centrifugal force, pulling the aircraft toward the inside of the turn.
Slot Time
Meter Fix Time/Slot Time.
Slow Taxi
To taxi a float plane at low power or low RPM.
Small
An Aircraft Class Wake Turbulence Separation Minima. Aircraft of 41,000 pounds or less maximum certificated takeoff weight.
Small aircraft
Aircraft of 12,500 pounds or less, maximum certificated takeoff weight.
Small airplane
An airplane of 12,500 pounds or less maximum certificated takeoff weight.
Smog
A mixture of smoke and fog.
Smoke
A restriction to visibility resulting from combustion.
Snow
Precipitation composed of white or translucent ice crystals, chiefly in complex branched hexagonal form.
Snow flurry
Popular term for snow shower, particularly of a very light and brief nature.
Snow grains
Precipitation of very small, white opaque grains of ice, similar in structure to snow crystals. The grains are fairly flat or elongated, with diameters generally less than 0.04 inch (1 mm.).
Snow pellets
Precipitation consisting of white, opaque approximately round (sometimes conical) ice particles having a snow-like structure, and about 0.08 to 0.2 inch in diameter; crisp and easily crushed, differing in this respect from snow grains; rebound from a hard surface and often break up.
Snow shower
Precipitation from a cumuliform cloud; characterized by the suddenness of beginning and ending, by the rapid change of intensity, and usually by rapid change in the appearance of the sky; showery precipitation in the form of ice pellets or snow.
Solar radiation
The total electromagnetic radiation emitted by the sun.
Somatogravic illusion
The misperception of being in a nose-up or nose-down attitude, caused by a rapid acceleration or deceleration while in flight situations that lack visual reference.
Sounding
In meteorology, an upper-air observation; a radiosonde observation.
Source
In communication, the sender, speaker, transmitter, or instructor who composes and transmits a message made up of symbols which are meaningful to listeners and readers.
Source region
An extensive area of the earth’s surface characterized by relatively uniform surface conditions where large masses of air remain long enough to take on characteristic temperature and moisture properties imparted by that surface.
Spatial disorientation
The state of confusion due to misleading information being sent to the brain from various sensory organs, resulting in a lack of awareness of the aircraft position in relation to a specific reference point.
Speak Slower
Used in verbal communications as a request to reduce speech rate.
Special Activity Airspace (SAA)
Any airspace with defined dimensions within the National Airspace System wherein limitations may be imposed upon aircraft operations. This airspace may be restricted areas, prohibited areas, military operations areas, air ATC assigned airspace, and any other designated airspace areas. The dimensions of this airspace are programmed into URET and can be designated as either active or inactive by screen entry. Aircraft trajectories are constantly tested against the dimensions of active areas and alerts issued to the applicable sectors when violations are predicted.
Special Emergency
A condition of air piracy or other hostile act by a person(s) aboard an aircraft which threatens the safety of the aircraft or its passengers.
Special flight permit
A flight permit issued to an aircraft that does not meet airworthiness requirements but is capable of safe flight. A special flight permit can be issued to move an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, or customer demonstration. Also referred to as a ferry permit.
Special fuel consumption
The amount of fuel in pounds per hour consumed or required by an engine per brake horsepower or per pound of thrust.
Special Instrument Approach Procedure
A procedure approved by the FAA for individual operators, but not published in FAR 97 for public use.
Special use airspace
Airspace in which flight activities are subject to restrictions that can create limitations on the mixed use of airspace. Consists of prohibited, restricted, warning, military operations, and alert areas.
Special Use Airspace Management System (SAMS)
A joint FAA and military program designed to improve civilian access to special use airspace by providing information on whether the airspace is active or scheduled to be active. The information is available to authorized users via an Internet website.
Special VFR conditions
Meteorological conditions that are less than those required for basic VFR flight in controlled airspace and in which some aircraft are permitted flight under visual flight rules.
Special VFR Flight [ICAO]
A VFR flight cleared by air traffic control to operate within Class B, C, D, and E surface areas in metrological conditions below VMC.
Special VFR operations
Aircraft operating in accordance with clearances within controlled airspace in meteorological conditions less than the basic VFR weather minima. Such operations must be requested by the pilot and approved by ATC.
Specific Fuel Consumption
Number of pounds of fuel consumed in 1 hour to produce 1 HP.
Specific humidity
The ratio by weight of water vapor in a sample of air to the combined weight of water vapor and dry air. Compare mixing ratio.
Speed
The distance traveled in a given time.
Speed Adjustment
An ATC procedure used to request pilots to adjust aircraft speed to a specific value for the purpose of providing desired spacing. Pilots are expected to maintain a speed of plus or minus 10 knots or 0.02 Mach number of the specified speed. Examples of speed adjustments are: a. “Increase/reduce speed to Mach point (number.)” b. “Increase/reduce speed to (speed in knots)” or “Increase/reduce speed (number of knots) knots.”
Speed Brakes
A control system that extends from the airplane structure into the airstream to produce drag and slow the airplane.
Speed Instability
A condition in the region of reverse command where a disturbance that causes the airspeed to decrease causes total drag to increase, which in turn, causes the airspeed to decrease further.
Speed Segments
Portions of the arrival route between the transition point and the vertex along the optimum flight path for which speeds and altitudes are specified. There is one set of arrival speed segments adapted from each transition point to each vertex. Each set may contain up to six segments.
Speed Sense
The ability to sense instantly and react to any reasonable variation of airspeed.
Spin
An aggravated stall that results in what is termed an “autorotation” wherein the airplane follows a downward corkscrew path. As the airplane rotates around the vertical axis, the rising wing is less stalled than the descending wing creating a rolling, yawing, and pitching motion.
Spiral Instability
A condition that exists when the static directional stability of the airplane is very strong as compared to the effect of its dihedral in maintaining lateral equilibrium.
Spiraling Slipstream
The slipstream of a propeller-driven airplane rotates around the airplane. This slipstream strikes the left side of the vertical fin, causing the airplane to yaw slightly. Vertical stabilizer offset is sometimes used by aircraft designers to counteract this tendency.
Split Shaft Turbine Engine
See Free Power Turbine Engine.
Spoilers
High-drag devices that can be raised into the air flowing over an airfoil, reducing lift and increasing drag. Spoilers are used for roll control on some aircraft. Deploying spoilers on both wings at the same time allows the aircraft to descend without gaining speed. Spoilers are also used to shorten the ground roll after landing.
Spool
A shaft in a turbine engine which drives one or more compressors with the power derived from one or more turbines.
Squall
A sudden increase in wind speed by at least 15 knots to a peak of 20 knots or more and lasting for at least one minute. Essential difference between a gust and a squall is the duration of the peak speed.
Squall line
Any nonfrontal line or narrow band of active thunderstorms (with or without squalls).
Squawk (Mode, Code, Function)
Activate specific modes/codes/functions on the aircraft transponder; e.g., “Squawk three/alpha, two one zero five, low.”
St. Elmo’s Fire
A corona discharge which lights up the aircraft surface areas where maximum static discharge occurs.
Stabilator
A single-piece horizontal tail surface on an airplane that pivots around a central hinge point. A stabilator serves the purposes of both the horizontal stabilizer and the elevator.
Stability
The inherent quality of an airplane to correct for conditions that may disturb its equilibrium, and to return or to continue on the original flightpath. It is primarily an airplane design characteristic.
Stabilized Approach
A landing approach in which the pilot establishes and maintains a constant angle glidepath towards a predetermined point on the landing runway. It is based on the pilot’s judgment of certain visual cues, and depends on the maintenance of a constant final descent airspeed and configuration.
Staging/Queuing
The placement, integration, and segregation of departure aircraft in designated movement areas of an airport by departure fix, EDCT, and/or restriction.
Stagnant hypoxia
A type of hypoxia that results when the oxygen-rich blood in the lungs is not moving to the tissues that need it.
Stagnation Point
The point on a surface where the local air velocity is zero. The region of maximum icing collection efficiency is near this point.
Stall
A rapid decrease in lift caused by the separation of airflow from the wing’s surface brought on by exceeding the critical angle of attack. A stall can occur at any pitch attitude or airspeed.
Stall Strips
A spoiler attached to the inboard leading edge of some wings to cause the center section of the wing to stall before the tips. This assures lateral control throughout the stall.
Stand By
Means the controller or pilot must pause for a few seconds, usually to attend to other duties of a higher priority. Also means to wait as in “stand by for clearance.” The caller should reestablish contact if a delay is lengthy. “Stand by” is not an approval or denial.
Standard Atmosphere
At sea level, the standard atmosphere consists of a barometric pressure of 29.92 inches of mercury (in. Hg.) or 1013.2 millibars, and a temperature of 15°C (59°F). Pressure and temperature normally decrease as altitude increases. The standard lapse rate in the lower atmosphere for each 1,000 feet of altitude is approximately 1 in. Hg. and 2°C (3.5°F). For example, the standard pressure and temperature at 3,000 feet mean sea level (MSL) is 26.92 in. Hg. 29.92" Hg – 3" Hg) and 9°C (15°C - 6°C).
Standard Day
See Standard Atmosphere.
Standard Empty Weight
(GAMA) Weight of a standard airplane including unusable fuel, full operating fluids, and full oil.
Standard Empty Weight (GAMA)
This weight consists of the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the airplane; including fixed ballast, hydraulic fluid, unusable fuel, and full engine oil.
Standard holding pattern
A holding pattern in which all turns are made to the right.
Standard I
An RNAV approach design for a single runway with both corner IAFs eliminated. Course reversal or radar vectoring may be required at busy terminals with multiple runways.
Standard Instrument Approach Procedure (SIAP)
Instrument Approach Procedure.
Standard Instrument Departure (SID)
An ATC requested and developed departure route designed to increase capacity of terminal airspace, effectively control the flow of traffic with minimal communication, and reduce environmental impact through noise abatement procedures.
Standard instrument departure procedures (SIDS)
Published procedures to expedite clearance delivery and to facilitate transition between takeoff and en route operations.
Standard instrument departure procedures (SIDS).
Published procedures to expedite clearance delivery and to facilitate transition between takeoff and en route operations.
Standard rate turn
A turn in which an aircraft changes its direction at a rate of 3° per second (360° in 2 minutes) for low- or medium-speed aircraft. For high-speed aircraft, the standard rate turn is 1 1⁄2° per second (360° in 4 minutes).
Standard Service Volume
Most air navigation radio aids which provide positive course guidance have a designated standard service volume (SSV). The SSV defines the reception limits of unrestricted NAVAIDS which are usable for random/unpublished route navigation. Standard service volume limitations do not apply to published IFR routes or procedures. See the AIM for the SSV for specific NAVAID types.
Standard service volume (SSV)
Defines the limits of the volume of airspace which the VOR serves.
Standard T
An RNAV approach whose design allows direct flight to any one of three initial approach fixes (IAF) and eliminates the need for procedure turns. The standard design is to align the procedure on the extended centerline with the missed approach point (MAP) at the runway threshold, the final approach fix (FAF), and the initial approach/intermediate fix (IAF/IF). The other two IAFs will be established perpendicular to the IF.
Standard Terminal Arrival
A preplanned instrument flight rule (IFR) air traffic control arrival procedure published for pilot use in graphic and/or textual form. STARs provide transition from the en route structure to an outer fix or an instrument approach fix/arrival waypoint in the terminal area.
Standard Terminal Arrival (STAR)
Provides a common method for departing the en route structure and navigating to your destination. A STAR is a preplanned instrument flight rule ATC arrival procedure published for pilot use in graphic and textual form to simplify clearance delivery procedures. STARs provide you with a transition from the en route structure to an outer fix or an instrument approach fix or arrival waypoint in the terminal area, and they usually terminate with an instrument or visual approach procedure.
Standard Terminal Arrival (STAR) Charts
Designed to expedite air traffic control arrival procedures and to facilitate transition between en route and instrument approach operations. Each STAR procedure is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location. i. Airport Taxi Charts Designed to expedite the efficient and safe flow of ground traffic at an airport. These charts are identified by the official airport name; e.g., Ronald Reagan Washington National Airport.
Standard Terminal Arrival Charts
Aeronautical Chart.
Standard terminal arrival route (STAR)
A preplanned IFR ATC arrival procedure published for pilot use in graphic and/or textual form.
Standard Terminal Automation Replacement System (STARS)
DTAS.
Standard Weights
These have been established for numerous items involved in weight and balance computations. These weights should not be used if actual weights are available.
Standard-Rate Turn
A turn at the rate of 3º per second which enables the airplane to complete a 360º turn in 2 minutes.
Standardized Taxi Routes
Coded taxi routes that follow typical taxiway traffic patterns to move aircraft between gates and runways. ATC issues clearances using these coded routes to reduce radio communication and eliminate taxi instruction misinterpretation.
Standing cloud
A lenticular cloud. (standing lenticular altocumulus) A species of cloud whose elements have the form of more or less isolated, generally smooth lenses or almonds. These clouds appear most often in formations of orographic origin, the result of lee waves, in which case they remain nearly stationary with respect to the terrain (standing cloud), but they also occur in regions without marked orography.
Standing wave
A wave that remains stationary in a moving fluid. In aviation operations it is used most commonly to refer to a lee wave or mountain wave.
STAR Transition
A published segment used to connect one or more en route airways, jet routes, or RNAV routes to the basic STAR procedure. It is one of several routes that bring traffic from different directions into one STAR. NACO publishes STARs for airports with procedures authorized by the FAA, and these STARs are included at the front of each Terminal Procedures Publication regional booklet.
Start End of Runway (SER)
The beginning of the takeoff runway available.
Starter/Generator
A combined unit used on turbine engines. The device acts as a starter for rotating the engine, and after running, internal circuits are shifted to convert the device into a generator.
State Aircraft
Aircraft used in military, customs and police service, in the exclusive service of any government, or of any political subdivision, thereof including the government of any state, territory, or possession of the United States or the District of Columbia, but not including any government-owned aircraft engaged in carrying persons or property for commercial purposes.
Static Load
The load imposed on an aircraft structure due to the weight of the aircraft and its contents.
Static longitudinal stability
The aerodynamic pitching moments required to return the aircraft to the equilibrium angle of attack.
Static pressure
Pressure of air that is still, or not moving, measured perpendicular to the surface of the aircraft.
Static Restrictions
Those restrictions that are usually not subject to change, fixed, in place, and/or published.
Static Stability
The initial tendency an aircraft displays when disturbed from a state of equilibrium.
Station
A location in the airplane that is identified by a number designating its distance in inches from the datum. The datum is, therefore, identified as station zero. An item located at station +50 would have an arm of 50 inches.
Station Declination
The angular difference between true north and the zero radial of a VOR at the time the VOR was last site checked.
Station pressure
The actual atmospheric pressure at the observing station.
Stationary front
Same as quasi-stationary front—a front which is stationary or nearly so; conventionally, a front which is moving at a speed of less than 5 knots is generally considered to be quasi-stationary.
Stationary Reservations
Altitude reservations which encompass activities in a fixed area. Stationary reservations may include activities, such as special tests of weapons systems or equipment, certain U.S. Navy carrier, fleet, and anti-submarine operations, rocket, missile and drone operations, and certain aerial refueling or similar operations.
Steam fog
Fog formed when cold air moves over relatively warm water or wet ground.
Steep turns
In instrument flight, any turn greater than standard rate; in visual flight, anything greater than a 45° bank.
Stem
The part of a multiple choice test item consisting of the question, statement, or problem.
Step Taxi
To taxi a float plane at full power or high RPM.
Step Turn
A maneuver used to put a float plane in a planing configuration prior to entering an active sea lane for takeoff. The STEP TURN maneuver should only be used upon pilot request.
Stepdown fix
The point after which additional descent is permitted within a segment of an IAP.
Stereo Route
A routinely used route of flight established by users and ARTCCs identified by a coded name; e.g., ALPHA 2. These routes minimize flight plan handling and communications.
Stick Puller
A device that applies aft pressure on the control column when the airplane is approaching the maximum operating speed.
Stick Pusher
A device that applies an abrupt and large forward force on the control column when the airplane is nearing an angle of attack where a stall could occur.
Stick Shaker
An artificial stall warning device that vibrates the control column.
STOL Aircraft
Short Takeoff And Landing Aircraft.
Stop Altitude Squawk
Used by ATC to inform an aircraft to turn-off the automatic altitude reporting feature of its transponder. It is issued when the verbally reported altitude varies 300 feet or more from the automatic altitude report.
Stop And Go
A procedure wherein an aircraft will land, make a complete stop on the runway, and then commence a takeoff from that point.
Stop Burst
Stop Stream.
Stop Buzzer
Stop Stream.
Stop Squawk (Mode Or Code)
Used by ATC to tell the pilot to turn specified functions of the aircraft transponder off.
Stop Stream
Used by ATC to request a pilot to suspend electronic attack activity.
Stopover Flight Plan
A flight plan format which permits in a single submission the filing of a sequence of flight plans through interim full-stop destinations to a final destination.
Stopway
An area beyond the takeoff runway, no less wide than the runway and centered upon the extended centerline of the runway, able to support the airplane during an aborted takeoff, without causing structural damage to the airplane, and designated by the airport authorities for use in decelerating the airplane during an aborted takeoff.
Storm detection radar
A weather radar designed to detect hydrometeors of precipitation size; used primarily to detect storms with large drops or hailstones as opposed to clouds and light precipitation of small drop size.
Straight-In Approach IFR
An instrument approach wherein final approach is begun without first having executed a procedure turn, not necessarily completed with a straight-in landing or made to straight-in landing minimums.
Straight-In Approach VFR
Entry into the traffic pattern by interception of the extended runway centerline (final approach course) without executing any other portion of the traffic pattern.
Straight-In Area
A type of Terminal Arrival Area. A 30NM arc centered on the IF (Intermediate Fix) bounded by a straight line extending through the IF perpendicular to the intermediate course.
Straight-In Landing
A landing made on a runway aligned within 30° of the final approach course following completion of an instrument approach.
Straight-In Landing Minimums
Landing Minimums.
Straight-In Minimums
Straight-In Landing Minimums.
Strain Sensor
A device that converts a physical phenomenon into an electrical signal. Strain sensors in a wheel axle sense the amount the axle deflects and create an electrical signal that is proportional to the force that caused the deflection.
Strapdown system
An INS in which the accelerometers and gyros are permanently strapped down or aligned with the three axes of the aircraft.
Strategic Planning
Planning whereby solutions are sought to resolve potential conflicts.
Stratiform
Descriptive of clouds of extensive horizontal development, as contrasted to vertically developed cumuliform clouds; characteristic of stable air and, therefore, composed of small water droplets.
Stratocumulus
A low cloud, predominantly stratiform in gray and/or whitish patches or layers, mayor may not merge; elements are tessellated, rounded, or roll-shaped with relatively flat tops.
Stratoshere
A layer of the atmosphere above the tropopause extending to a height of approximately 160,000 feet.
Stratosphere
The atmospheric layer above the tropopause, average altitude of base and top, 7 and 22 miles respectively; characterized by a slight average increase of temperature from base to top and is very stable; also characterized by low moisture content and absence of clouds.
Stratus
A low, gray cloud layer or sheet with a fairly uniform base; sometimes appears in ragged patches; seldom produces precipitation but may produce drizzle or snow grains. A stratiform cloud.
Stratus Clouds.
Clouds that form layers with a uniform base. Stratus clouds can appear in ragged patches and may produce drizzle, rain, or snow.
Stratus fractus
A stratus layer (low, gray cloud layer or sheet) that has a base in the form of irregular shreds (fractus), appearing as if torn.
Streamline
In meteorology, a line whose tangent is the wind direction at any point along the line. A flowline.
Stress
The body’s response to demands placed upon it.
Stress management
The personal analysis of the kinds of stress experienced while flying, the application of appropriate stress assessment tools, and other coping mechanisms.
Stress Risers
A scratch, groove, rivet hole, forging defect or other structural discontinuity that causes a concentration of stress.
Structural icing
The accumulation of ice on the exterior of the aircraft.
Structural Station
This is a location in the aircraft, such as a bulkhead, which is identified by a number designating its distance in inches or percent MAC from the datum. The datum is, therefore, identified as station zero. The stations and arms are identical. An item located at station +50 would have an arm of 50 inches.
Sublimation
The change of (a) ice to water vapor or (b) water vapor to ice.
Subrefraction
Less than normal bending of the radar beam resulting from abnormal vertical gradients of temperature and/or water vapor.
Subsidence
A descending motion of air in the atmosphere over a rather broad area; usually associated with divergence.
Subsonic
Speed below the speed of sound.
Substitute Route
A route assigned to pilots when any part of an airway or route is unusable because of NAVAID status. These routes consist of: a. Substitute routes which are shown on U.S. Government charts. b. Routes defined by ATC as specific NAVAID radials or courses. c. Routes defined by ATC as direct to or between NAVAIDs.
Suction relief valve
A relief valve in an instrument vacuum system required to maintain the correct low pressure inside the instrument case for the proper operation of the gyros.
Suitable RNAV system
An RNAV system that meets the required performance established for a type of operation, e.g. IFR; and is suitable for operation over the route to be flown in terms of any performance criteria (including accuracy) established by the air navigation service provider for certain routes (e.g. oceanic, ATS routes, and IAPs). An RNAV system’s suitability is dependent upon the availability of ground and/or satellite navigation aids that are needed to meet any route performance criteria that may be prescribed in route specifications to navigate the aircraft along the route to be flown. Information on suitable RNAV systems is published in FAA guidance material.
Summation principle
The principle states that the cover assigned to a layer is equal to the summation of the sky cover of the lowest layer plus the additional coverage at all successively higher layers up to and including the layer in question. Thus, no layer can be assigned a sky cover less than a lower layer, and no sky cover can be greater than 1.0 (10/10).
Sunset And Sunrise
The mean solar times of sunset and sunrise as published in the Nautical Almanac, converted to local standard time for the locality concerned. Within Alaska, the end of evening civil twilight and the beginning of morning civil twilight, as defined for each locality.
Super High Frequency
The frequency band between 3 and 30 gigahertz (GHz). The elevation and azimuth stations of the microwave landing system operate from 5031 MHz to 5091 MHz in this spectrum.
Superadiabatic lapse rate
A lapse rate greater than the dry-adiabatic lapse rate.
Supercharger
An engine or exhaust-driven air compressor used to provide additional pressure to the induction air so the engine can produce additional power.
Supercooled Large Drops (SLD)
Water drops with a diameter greater than 50 micrometers (0.05 mm) that exist in a liquid form at air temperatures below 0 °C. SLD conditions include freezing drizzle drops and freezing raindrops.
Supercooled water
Liquid water at temperatures colder than freezing.
Supercooled water droplets
Water droplets that have been cooled below the freezing point, but are still in a liquid state.
Superrefraction
More than normal bending of the radar beam resulting from abnormal vertical gradients of temperature and/or water vapor. (3)
Supersonic
Speed above the speed of sound.
Supplemental Type Certificate (STC)
A certificate authorizing an alteration to an airframe, engine, or component that has been granted an Approved Type Certificate.
Supplemental Weather Service Location
Airport facilities staffed with contract personnel who take weather observations and provide current local weather to pilots via telephone or radio. (All other services are provided by the parent FSS.
Supply-type test item
Question in which the student supplies answers as opposed to selecting from choices provided. Essay or fill-in-the blank type questions are examples of supply- type test items.
Surface analysis chart
A report that depicts an analysis of the current surface weather. Shows the areas of high and low pressure, fronts, temperatures, dewpoints, wind directions and speeds, local weather, and visual obstructions.
Surface Area
The airspace contained by the lateral boundary of the Class B, C, D, or E airspace designated for an airport that begins at the surface and extends upward.
Surface Incident
An event during which authorized or unauthorized/unapproved movement occurs in the movement area or an occurrence in the movement area associated with the operation of an aircraft that affects or could affect the safety of flight.
Surface inversion
An inversion with its base at the surface, often caused by cooling of the air near the surface as a result of terrestrial radiation, especially at night.
Surface Movement Guidance Control System (SMGCS)
Facilitates the safe movement of aircraft and vehicles at airports where scheduled air carriers are conducting authorized operations. The SMGCS low visibility taxi plan includes the improvement of taxiway and runway signs, markings, and lighting, as well as the creation of SMGCS low visibility taxi route charts.
Surface visibility
Visibility observed from eye-level above the ground.
Surveillance Approach
An instrument approach wherein the air traffic controller issues instructions, for pilot compliance, based on aircraft position in relation to the final approach course (azimuth), and the distance (range) from the end of the runway as displayed on the controller’s radar scope. The controller will provide recommended altitudes on final approach if requested by the pilot.
Swept Wing
A wing planform in which the tips of the wing are farther back than the wing root.
Symbols
In communication, simple oral and visual codes such as words, gestures, and facial expressions which are formed into sentences, paragraphs, lectures, or chapters to compose and transmit a message that means something to the receiver of the information.
Synchro
A device used to transmit indications of angular movement or position from one location to another.
Synoptic chart
A chart, such as the familiar weather map, which depicts the distribution of meteorological conditions over an area at a given time.
Synthetic Vision
A visual display of terrain, obstructions, runways, and other surface features that creates a virtual view of what the pilot would see out the window. This tool could be used to supplement normal vision in low visibility conditions, as well as to increase situational awareness in IMC.
Synthetic vision system
An electronic means to display a synthetic vision image of the external scene topography to the flight crew.
System Strategic Navigation
Military activity accomplished by navigating along a preplanned route using internal aircraft systems to maintain a desired track. This activity normally requires a lateral route width of 10 NM and altitude range of 1,000 feet to 6,000 feet AGL with some route segments that permit terrain following.
T-Tail
An aircraft with the horizontal stabilizer mounted on the top of the vertical stabilizer, forming a T.
Tacan-Only Aircraft
An aircraft, normally military, possessing TACAN with DME but no VOR navigational system capability. Clearances must specify TACAN or VORTAC fixes and approaches.
Tactical Air Navigation
An ultra-high frequency electronic rho-theta air navigation aid which provides suitably equipped aircraft a continuous indication of bearing and distance to the TACAN station.
Tactical air navigation (TACAN)
An electronic navigation system used by military aircraft, providing both distance and direction information.
Tailwheel Aircraft
See Conventional landing Gear.
Tailwind
Any wind more than 90 degrees to the longitudinal axis of the runway. The magnetic direction of the runway shall be used as the basis for determining the longitudinal axis.
Take-Off Distance Available [ICAO]
The length of the take-off run available plus the length of the clearway, if provided.
Take-Off Run Available [ICAO]
The length of runway declared available and suitable for the ground run of an aeroplane take-off.
Takeoff Area
Landing Area.
Takeoff decision speed (V1)
Per 14 CFR section 23.51: “the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot assumed to have made a decision to continue or discontinue the takeoff.”.
Takeoff distance
The distance required to complete an all-engines operative takeoff to the 35-foot height. It must be at least 15 percent less than the distance required for a one-engine inoperative engine takeoff. This distance is not normally a limiting factor as it is usually less than the one-engine inoperative takeoff distance.
Takeoff Distance Available (TODA)
ICAO defines TODA as the length of the takeoff runway available plus the length of the clearway, if provided.
Takeoff power
(1) With respect to reciprocating engines, the brake horsepower that is developed under standard sea level conditions, and under the maximum conditions of crankshaft rotational speed and engine manifold pressure approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification; and
(2) With respect to turbine engines, the brake horsepower that is developed under static conditions at a specified altitude and atmospheric temperature, and under the maximum conditions of rotor shaft rotational speed and gas temperature approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification.
Takeoff Roll (Ground Roll)
The total distance required for an aircraft to become airborne.
Takeoff Run Available (TORA)
The runway length declared available and suitable for the ground run of an airplane taking off.
Takeoff Runway Available (TORA)
ICAO defines TORA as the length of runway declared available and suitable for the ground run of an aeroplane takeoff.
Takeoff safety speed
A referenced airspeed obtained after lift-off at which the required one-engine-inoperative climb performance can be achieved.
Takeoff safety speed (V2)
Per 14 CFR part 1: “A referenced airspeed obtained after lift-off at which the required one-engine-inoperative climb performance can be achieved.”.
Takeoff thrust
With respect to turbine engines, the jet thrust that is developed under static conditions at a specific altitude and atmospheric temperature under the maximum conditions of rotorshaft rotational speed and gas temperature approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification.
Takeoff Weight
The weight of an aircraft just before beginning the takeoff roll. It is the ramp weight less the weight of the fuel burned during start and taxi.
Tandem wing configuration
A configuration having two wings of similar span, mounted in tandem.
Tangent Point (TP)
The point on the VOR/DME RNAV route centerline from which a line perpendicular to the route centerline would pass through the reference facility.
Tare Weight
The weight of any chocks or devices that are used to hold an aircraft on the scales when it is weighed. The tare weight must be subtracted from the scale reading to get the net weight of the aircraft.
Target
In radar, any of the many types of objects detected by radar.
Target Resolution
A process to ensure that correlated radar targets do not touch. Target resolution must be applied as follows: a. Between the edges of two primary targets or the edges of the ASR-9/11 primary target symbol. b. Between the end of the beacon control slash and the edge of a primary target. c. Between the ends of two beacon control slashes. Note 1: Mandatory traffic advisories and safety alerts must be issued when this procedure is used. Note 2: This procedure must not be used when utilizing mosaic radar systems or multi-sensor mode.
Target Reverser
A thrust reverser in a jet engine in which clamshell doors swivel from the stowed position at the engine tailpipe to block all of the outflow and redirect some component of the thrust forward.
Target Symbol
A computer-generated indication shown on a radar display resulting from a primary radar return or a radar beacon reply.
Target [ICAO]
In radar: a. Generally, any discrete object which reflects or retransmits energy back to the radar equipment. b. Specifically, an object of radar search or surveillance.
Tarmac Delay
The holding of an aircraft on the ground either before departure or after landing with no opportunity for its passengers to deplane.
Tarmac Delay Aircraft
An aircraft whose pilot-in-command has requested to taxi to the ramp, gate, or alternate deplaning area to comply with the Three-hour Tarmac Rule.
Tarmac Delay Request
A request by the pilot-in-command to taxi to the ramp, gate, or alternate deplaning location to comply with the Three-hour Tarmac Rule.
Task
Knowledge area, flight procedure, or maneuver within an area of operation in a practical test standard.
Taxi
The movement of an airplane under its own power on the surface of an airport (14 CFR Section 135.100 [Note]). Also, it describes the surface movement of helicopters equipped with wheels.
Taxi Patterns
Patterns established to illustrate the desired flow of ground traffic for the different runways or airport areas available for use.
Taxiway Lights
Omnidirectional lights that outline the edges of the taxiway and are blue in color.
Taxiway Turnoff Lights
Flush lights which emit a steady green color.
Taxonomy of educational objectives
A systematic classification scheme for sorting learning outcomes into three broad categories (cognitive, affective, and psychomotor) and ranking the desired outcomes in a developmental hierarchy from least complex to most complex.
Teaching
Instructing, training, or imparting knowledge or skill; the profession of someone who teaches.
Teaching lecture
An oral presentation that is directed toward desired learning outcomes. Some student participation is allowed.
Technique
The manner in which procedures are executed.
Telephone Information Briefing Service
A continuous telephone recording of meteorological and/or aeronautical information. Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.
Telephone information briefing service (TIBS)
Telephone recording of area and/or route meteorological briefings, airspace procedures, and special aviation-oriented announcements. Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.
Telling-and-doing technique
A technique of flight instruction that consists of the instructor first telling the student about a new procedure and then demonstrating it. This is followed by the student telling and the instructor doing. Third, the student explains the new procedure while doing it. Last, the instructor evaluates while the student performs the procedure.
Temperature
In general, the degree of hotness or coldness as measured on some definite temperature scale by means of any of various types of thermometers.
Temperature inversion
Inversion. An increase in temperature with height-a reversal of the normal decrease with height in the troposphere; may also be applied to other meteorological properties.
Temporary Ballast
Weights that can be carried in a cargo compartment of an aircraft to move the location of CG for a specific flight condition. Temporary ballast must be removed when the aircraft is weighed.
Temporary flight restriction (TFR)
Restriction to flight imposed in order to:
1. Protect persons and property in the air or on the surface from an existing or imminent flight associated hazard;
2. Provide a safe environment for the operation of disaster relief aircraft;
3. Prevent an unsafe congestion of sightseeing aircraft above an incident;
4. Protect the President, Vice President, or other public figures; and,
5. Provide a safe environment for space agency operations.
Pilots are expected to check appropriate NOTAMs during flight planning when conducting flight in an area where a temporary flight restriction is in effect.
Tension
Maintaining an excessively strong grip on the control column, usually resulting in an overcontrolled situation.
Tentative Calculated Landing Time
A projected time calculated for adapted vertex for each arrival aircraft based upon runway configuration, airport acceptance rate, airport arrival delay period, and other metered arrival aircraft. This time is either the VTA of the aircraft or the TCLT/ACLT of the previous aircraft plus the AAI, whichever is later. This time will be updated in response to an aircraft’s progress and its current relationship to other arrivals.
Terminal aerodrome forecast (TAF)
A report established for the 5 statute mile radius around an airport. Utilizes the same descriptors and abbreviations as the METAR report.
Terminal Area
A general term used to describe airspace in which approach control service or airport traffic control service is provided.
Terminal Area Facility
A facility providing air traffic control service for arriving and departing IFR, VFR, Special VFR, and on occasion en route aircraft.
Terminal Arrival Area (TAA)
TAAs are the method by which aircraft are transitioned from the RNAV en route structure to the terminal area with minimal ATC interaction. The TAA consists of a designated volume of airspace designed to allow aircraft to enter a protected area, offering guaranteed obstacle clearance where the initial approach course is intercepted based on the location of the aircraft relative to the airport.
Terminal Automation Systems (TAS)
TAS is used to identify the numerous automated tracking systems including ARTS IIE, ARTS IIIA, ARTS IIIE, STARS, and MEARTS.
Terminal Data Link System (TDLS)
A system that provides Digital Automatic Terminal Information Service (D-ATIS) both on a specified radio frequency and also, for subscribers, in a text message via data link to the cockpit or to a gate printer. TDLS also provides Pre-departure Clearances (PDC), at selected airports, to subscribers, through a service provider, in text to the cockpit or to a gate printer. In addition, TDLS will emulate the Flight Data Input/Output (FDIO) information within the control tower.
Terminal instrument approach procedure (TERP)
Prescribes standardized methods for use in designing instrument flight procedures.
Terminal Instrument Approach Procedure (TERP).
Prescribes standardized methods for use in designing instrument flight procedures.
Terminal Radar Service Area
Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. The AIM contains an explanation of TRSA. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
Terminal radar service areas (TRSA)
Areas where participating pilots can receive additional radar services. The purpose of the service is to provide separation between all IFR operations and participating VFR aircraft.
Terminal VFR Radar Service
A national program instituted to extend the terminal radar services provided instrument flight rules (IFR) aircraft to visual flight rules (VFR) aircraft. The program is divided into four types service referred to as basic radar service, terminal radar service area (TRSA) service, Class B service and Class C service. The type of service provided at a particular location is contained in the Airport/Facility Directory.
Terminal-Very High Frequency Omnidirectional Range Station
A very high frequency terminal omnirange station located on or near an airport and used as an approach aid.
Terrain Awareness and Warning System (TAWS)
A timed-based system that provides information concerning potential hazards with fixed objects by using GPS positioning and a database of terrain and obstructions to provide true predictability of the upcoming terrain and obstacles.
Terrain Awareness Warning System (TAWS)
An on-board, terrain proximity alerting system providing the aircrew `Low Altitude warnings’ to allow immediate pilot action.
Terrain Following
The flight of a military aircraft maintaining a constant AGL altitude above the terrain or the highest obstruction. The altitude of the aircraft will constantly change with the varying terrain and/or obstruction.
Terrain/Obstruction Alert
A safety alert issued by ATC to aircraft under their control if ATC is aware the aircraft is at an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to terrain/obstructions; e.g., “Low Altitude Alert, check your altitude immediately.”
Terrestrial radiation
The total infrared radiation emitted by the Earth and its atmosphere.
Test
A set of questions, problems, or exercises for determining whether a person has a particular knowledge or skill.
Test item
A question, problem, or exercise that measures a single objective and requires a single response.
Tetrahedron
A large, triangular-shaped, kite-like object installed near the runway. Tetrahedrons are mounted on a pivot and are free to swing with the wind to show the pilot the direction of the wind as an aid in takeoffs and landings.
That Is Correct
The understanding you have is right.
Theodolite
An optical instrument which, in meteorology, is used principally to observe the motion of a pilot balloon.
Thermograph
A continuous-recording thermometer.
Thermometer
An instrument for measuring temperature.
Thermosphere
The last layer of the atmosphere that begins above the mesosphere and gradually fades away into space.
Three-Hour Tarmac Rule
Rule that relates to Department of Transportation (DOT) requirements placed on airlines when tarmac delays are anticipated to reach 3 hours.
Threshold
The beginning of the part of the runway usable for landing.
Threshold Crossing Height
The theoretical height above the runway threshold at which the aircraft’s glideslope antenna would be if the aircraft maintains the trajectory established by the mean ILS glideslope or MLS glidepath.
Threshold crossing height (TCH)
The theoretical height above the runway threshold at which the aircrafts glide slope antenna would be if the aircraft maintains the trajectory established by the mean ILS glide slope or MLS glide path.
Threshold Lights
Airport Lighting.
Throttle
The valve in a carburetor or fuel control unit that determines the amount of fuel-air mixture that is fed to the engine.
Thrust
The force which imparts a change in the velocity of a mass. This force is measured in pounds but has no element of time or rate. The term, thrust required, is generally associated with jet engines. A forward force which propels the airplane through the air.
Thrust (aerodynamic force)
The forward aerodynamic force produced by a propeller, fan, or turbojet engine as it forces a mass of air to the rear, behind the aircraft.
Thrust Line
An imaginary line passing through the center of the propeller hub, perpendicular to the plane of the propeller rotation.
Thrust Reversers
Devices which redirect the flow of jet exhaust to reverse the direction of thrust.
Thunderstorm
In general, a local storm invariably produced by a cumulonimbus cloud, and always accompanied by lightning and thunder.
Time and opportunity
A perception factor in which learning something is dependent on the student having the time to sense and relate current experiences in context with previous events.
Time and speed table
A table depicted on an instrument approach procedure chart that identifies the distance from the FAF to the MAP, and provides the time required to transit that distance based on various groundspeeds.
Time Group
Four digits representing the hour and minutes from the Coordinated Universal Time (UTC) clock. FAA uses UTC for all operations. The term “ZULU” may be used to denote UTC. The word “local” or the time zone equivalent shall be used to denote local when local time is given during radio and telephone communications. When written, a time zone designator is used to indicate local time; e.g. “0205M” (Mountain). The local time may be based on the 24-hour clock system. The day begins at 0000 and ends at 2359.
Time in service
With respect to maintenance time records, the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing.
Timed turn
A turn in which the clock and the turn coordinator are used to change heading a definite number of degrees in a given time.
Timing
The application of muscular coordination at the proper instant to make flight, and all maneuvers incident thereto, a constant smooth process.
Tire Cord
Woven metal wire laminated into the tire to provide extra strength. A tire showing any cord must be replaced prior to any further flight.
Top of Climb (TOC)
An identifiable waypoint representing the point at which cruise altitude is first reached. TOC is calculated based on your current aircraft altitude, climb speed, and cruise altitude. There can only be one TOC waypoint at a time.
Top of Descent (TOD)
Generally utilized in flight management systems, top of descent is an identifiable waypoint representing the point at which descent is first initiated from cruise altitude. TOD is generally calculated using the destination elevation (if available) and the descent speed schedule.
Torching
The burning of fuel at the end of an exhaust pipe or stack of a reciprocating aircraft engine, the result of an excessive richness in the fuel air mixture.
Tornado (sometimes called cyclone, twister)
A violently rotating column of air, pendant from a cumulonimbus cloud, and nearly always observable as “funnel-shaped.” It is the most destructive of all small-scale atmospheric phenomena.
Torque
1. A resistance to turning or twisting.
2. Forces that produce a twisting or rotating motion.
3. In an airplane, the tendency of the aircraft to turn (roll) in the opposite direction of rotation of the engine and propeller.
Torque Meter
An indicator used on some large reciprocating engines or on turboprop engines to indicate the amount of torque the engine is producing.
Torque Sensor
See Torque Meter.
Torquemeter
An instrument used with some of the larger reciprocating engines and turboprop or turboshaft engines to measure the reaction between the propeller reduction gears and the engine case.
Total Drag
The sum of the parasite and induced drag.
Total Estimated Elapsed Time [ICAO]
For IFR flights, the estimated time required from take-off to arrive over that designated point, defined by reference to navigation aids, from which it is intended that an instrument approach procedure will be commenced, or, if no navigation aid is associated with the destination aerodrome, to arrive over the destination aerodrome. For VFR flights, the estimated time required from take-off to arrive over the destination aerodrome.
Touch-And-Go
An operation by an aircraft that lands and departs on a runway without stopping or exiting the runway.
Touch-And-Go Landing
Touch-And-Go.
Touchdown
A. The point at which an aircraft first makes contact with the landing surface.
B. Concerning a precision radar approach (PAR), it is the point where the glide path intercepts the landing surface.
Touchdown and Lift-Off Area (TLOF)
The TLOF is a load bearing, usually paved area at a heliport where the helicopter is permitted to land. The TLOF can be located at ground or rooftop level, or on an elevated structure. The TLOF is normally centered in the FATO.
Touchdown RVR
The RVR visibility readout values obtained from sensors serving the runway touchdown zone.
Touchdown Zone
The first 3,000 feet of the runway beginning at the threshold. The area is used for determination of Touchdown Zone Elevation in the development of straight-in landing minimums for instrument approaches.
Touchdown Zone Elevation
The highest elevation in the first 3,000 feet of the landing surface. TDZE is indicated on the instrument approach procedure chart when straight-in landing minimums are authorized.
Touchdown Zone Elevation (TDZE)
The highest elevation in the first 3,000 feet of the landing surface.
Touchdown Zone Lighting
Airport Lighting.
Touchdown Zone Lights
Two rows of transverse light bars disposed symmetrically about the runway centerline in the runway touchdown zone.
Touchdown Zone [ICAO]
The portion of a runway, beyond the threshold, where it is intended landing aircraft first contact the runway.
Touchdown [ICAO]
The point where the nominal glide path intercepts the runway. Note: Touchdown as defined above is only a datum and is not necessarily the actual point at which the aircraft will touch the runway.
Tower
A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar or nonradar).
Tower En Route Control (TEC)
The control of IFR en route traffic within delegated airspace between two or more adjacent approach control facilities. This service is designed to expedite air traffic and reduces air traffic control and pilot communication requirements.
Tower En Route Control Service
The control of IFR en route traffic within delegated airspace between two or more adjacent approach control facilities. This service is designed to expedite traffic and reduce control and pilot communication requirements.
Tower To Tower
Tower En Route Control Service.
Tower visibility
Prevailing VIsibility determined from the control tower.
Towering cumulus
A rapidly growing cumulus in which height exceeds width.
Trace Icing
Ice becomes perceptible. Rate of accumulation is slightly greater than the rate of sublimation. Deicing/anti-icing equipment is not utilized unless encountered for an extended period of time (over 1 hour).
Traceable Pressure Standard
The facility station pressure instrument, with certification/calibration traceable to the National Institute of Standards and Technology. Traceable pressure standards may be mercurial barometers, commissioned ASOS/AWSS or dual transducer AWOS, or portable pressure standards or DASI.
Track
The actual path made over the ground in flight.
Track Of Interest (TOI)
Displayed data representing an airborne object that threatens or has the potential to threaten North America or National Security. Indicators may include, but are not limited to: noncompliance with air traffic control instructions or aviation regulations; extended loss of communications; unusual transmissions or unusual flight behavior; unauthorized intrusion into controlled airspace or an ADIZ; noncompliance with issued flight restrictions/security procedures; or unlawful interference with airborne flight crews, up to and including hijack. In certain circumstances, an object may become a TOI based on specific and credible intelligence pertaining to that particular aircraft/object, its passengers, or its cargo.
Track Of Interest Resolution
A TOI will normally be considered resolved when: the aircraft/object is no longer airborne; the aircraft complies with air traffic control instructions, aviation regulations, and/or issued flight restrictions/security procedures; radio contact is re-established and authorized control of the aircraft is verified; the aircraft is intercepted and intent is verified to be nonthreatening/nonhostile; TOI was identified based on specific and credible intelligence that was later determined to be invalid or unreliable; or displayed data is identified and characterized as invalid.
Track [ICAO]
The projection on the earth’s surface of the path of an aircraft, the direction of which path at any point is usually expressed in degrees from North (True, Magnetic, or Grid).
Tracking
Flying a heading that will maintain the desired track to or from the station regardless of crosswind conditions.
Trade winds
Prevailing, almost continuous winds blowing with an easterly component from the subtropical high pressure belts toward the intertropical convergence cone; northeast in the Northern Hemisphere, southeast in the Southern Hemisphere.
Traditional assessment
Written testing, such as multiple choice, matching, true/false, or fill-in-the-blank.
Traffic
A. A term used by a controller to transfer radar identification of an aircraft to another controller for the purpose of coordinating separation action. Traffic is normally issued:
1. In response to a handoff or point out,
2. In anticipation of a handoff or point out, or
3. In conjunction with a request for control of an aircraft.
B. A term used by ATC to refer to one or more aircraft.
Traffic Advisories
Advisories issued to alert pilots to other known or observed air traffic which may be in such proximity to the position or intended route of flight of their aircraft to warrant their attention. Such advisories may be based on: a. Visual observation. b. Observation of radar identified and nonidentified aircraft targets on an ATC radar display, or c. Verbal reports from pilots or other facilities. Note 1: The word “traffic” followed by additional information, if known, is used to provide such advisories; e.g., “Traffic, 2 o’clock, one zero miles, southbound, eight thousand.” Note 2: Traffic advisory service will be provided to the extent possible depending on higher priority duties of the controller or other limitations; e.g., radar limitations, volume of traffic, frequency congestion, or controller workload. Radar/ nonradar traffic advisories do not relieve the pilot of his/her responsibility to see and avoid other aircraft. Pilots are cautioned that there are many times when the controller is not able to give traffic advisories concerning all traffic in the aircraft’s proximity; in other words, when a pilot requests or is receiving traffic advisories, he/she should not assume that all traffic will be issued.
Traffic Alert
(aircraft call sign), TURN (left/right) IMMEDIATELY, (climb/descend) AND MAINTAIN (altitude).
Traffic Alert And Collision Avoidance System
An airborne collision avoidance system based on radar beacon signals which operates independent of ground-based equipment. TCAS-I generates traffic advisories only. TCAS-II generates traffic advisories, and resolution (collision avoidance) advisories in the vertical plane.
Traffic Alert Collision Avoidance System (TCAS)
An airborne system developed by the FAA that operates independently from the ground-based Air Traffic Control system. Designed to increase flight deck awareness of proximate aircraft and to serve as a “last line of defense” for the prevention of midair collisions.
Traffic Alert Collision Avoidance System (TCAS).
An airborne system developed by the FAA that operates independently from the ground-based Air Traffic Control system. Designed to increase flight deck awareness of proximate aircraft and to serve as a last line of defense for the prevention of mid-air collisions.
Traffic In Sight
Used by pilots to inform a controller that previously issued traffic is in sight.
Traffic Information
Traffic Advisories.
Traffic information service (TIS)
A ground-based service providing information to the flight deck via data link using the S-mode transponder and altitude encoder to improve the safety and efficiency of see and avoid flight through an automatic display that informs the pilot of nearby traffic.
Traffic Information Service-Broadcast (TIS-B)
An air traffic surveillance system that combines all available traffic information on a single display.
Traffic Management Advisor (TMA)
A software suite that helps air traffic controllers to sequence arriving air traffic.
Traffic Management Program Alert
A term used in a Notice to Airmen (NOTAM) issued in conjunction with a special traffic management program to alert pilots to the existence of the program and to refer them to either the Notices to Airmen publication or a special traffic management program advisory message for program details. The contraction TMPA is used in NOTAM text.
Traffic Management Unit
The entity in ARTCCs and designated terminals directly involved in the active management of facility traffic. Usually under the direct supervision of an assistant manager for traffic management.
Traffic No Factor
Indicates that the traffic described in a previously issued traffic advisory is no factor.
Traffic No Longer Observed
Indicates that the traffic described in a previously issued traffic advisory is no longer depicted on radar, but may still be a factor.
Traffic pattern
The traffic flow that is prescribed for aircraft landing at, taxiing on, or taking off from, an airport.
Traffic Situation Display (TSD)
TSD is a computer system that receives radar track data from all 20 CONUS ARTCCs, organizes this data into a mosaic display, and presents it on a computer screen. The display allows the traffic management coordinator multiple methods of selection and highlighting of individual aircraft or groups of aircraft. The user has the option of superimposing these aircraft positions over any number of background displays. These background options include ARTCC boundaries, any stratum of en route sector boundaries, fixes, airways, military and other special use airspace, airports, and geopolitical boundaries. By using the TSD, a coordinator can monitor any number of traffic situations or the entire systemwide traffic flows.
Trailing Edge
The portion of the airfoil where the airflow over the upper surface rejoins the lower surface airflow.
Training course outline
Within a curriculum, describes the content of a particular course by statement of objectives, descriptions of teaching aids, definition of evaluation criteria, and indication of desired outcome.
Training media
Any physical means that communicates an instructional message to students.
Training syllabus
A step by- step, building block progression of learning with provisions for regular review and evaluations at prescribed stages of learning. The syllabus defines the unit of training, states by objective what the student is expected to accomplish during the unit of training, shows an organized plan for instruction, and dictates the evaluation process for either the unit or stages of learning.
Trajectory
A URET representation of the path an aircraft is predicted to fly based upon a Current Plan or Trial Plan.
Trajectory Modeling
The automated process of calculating a trajectory.
Transcribed Weather Broadcast (TWEB)
Meteorological and aeronautical data recorded on tapes and broadcast over selected NAVAIDs. Generally, the broadcast contains route-oriented data with specially prepared NWS forecasts, inflight advisories, and winds aloft. It also includes selected current information such as weather reports (METAR/SPECI), NOTAMs, and special notices. Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.
Transfer Of Control
That action whereby the responsibility for the separation of an aircraft is transferred from one controller to another.
Transfer Of Control [ICAO]
Transfer of responsibility for providing air traffic control service.
Transfer of learning
The ability to apply knowledge or procedures learned in one context to new contexts.
Transferring Controller
A controller/facility transferring control of an aircraft to another controller/facility.
Transferring Facility
Transferring Controller.
Transferring Unit/Controller [ICAO]
Air traffic control unit/air traffic controller in the process of transferring the responsibility for providing air traffic control service to an aircraft to the next air traffic control unit/air traffic controller along the route of flight. Note: See definition of accepting unit/controller.
Transition
A published procedure (DP Transition) used to connect the basic DP to one of several en route airways/jet routes, or a published procedure (STAR Transition) used to connect one of several en route airways/jet routes to the basic STAR.
Transition Altitude (QNH)
The altitude in the vicinity of an airport at or below which the vertical position of an aircraft is controlled by reference to altitudes (MSL).
Transition Height (QFE)
Transition height is the height in the vicinity of an airport at or below which the vertical position of an aircraft is expressed in height above the airport reference datum.
Transition Layer
Transition layer is the airspace between the transition altitude and the transition level. Aircraft descending through the transition layer will set altimeters to local station pressure, while departing aircraft climbing through the transition layer will be using standard altimeter setting (QNE) of 29.92 inches of Mercury, 1013.2 millibars, or 1013.2 hectopascals.
Transition Level (QNE)
The lowest flight level available for use above the transition altitude.
Transition Liner
The portion of the combustor that directs the gases into the turbine plenum.
Transition Point
A point at an adapted number of miles from the vertex at which an arrival aircraft would normally commence descent from its en route altitude. This is the first fix adapted on the arrival speed segments.
Transition training
An instructional program designed to familiarize and qualify a pilot to fly types of aircraft not previously flown, such as tail wheel aircraft, high performance aircraft, and aircraft capable of flying at high altitudes.
Transition Waypoint
The waypoint that defines the beginning of a runway or en route transition on an RNAV SID or STAR.
Transitional Airspace
That portion of controlled airspace wherein aircraft change from one phase of flight or flight condition to another.
Transmissometer
An instrument system which shows the transmissivity of light through the atmosphere. Transmissivity may be translated either automatically or manually into visibility and/or runway visual range.
Transmitting In The Blind
A transmission from one station to other stations in circumstances where two-way communication cannot be established, but where it is believed that the called stations may be able to receive the transmission.
Transonic
At the speed of sound.
Transponder
The airborne portion of the secondary surveillance radar system. The transponder emits a reply when queried by a radar facility.
Transponder code
One of 4,096 four-digit discrete codes ATC assigns to distinguish between aircraft.
Transponder Codes
Codes.
Transponder Observed
Phraseology used to inform a VFR pilot the aircraft’s assigned beacon code and position have been observed. Specifically, this term conveys to a VFR pilot the transponder reply has been observed and its position correlated for transit through the designated area.
Transponder [ICAO]
A receiver/transmitter which will generate a reply signal upon proper interrogation; the interrogation and reply being on different frequencies.
Trend
Immediate indication of the direction of aircraft movement, as shown on instruments.
Trial Plan
A proposed amendment which utilizes automation to analyze and display potential conflicts along the predicted trajectory of the selected aircraft.
Tricycle Gear
Landing gear employing a third wheel located on the nose of the aircraft.
Trim
Adjusting the aerodynamic forces on the control surfaces so that the aircraft maintains the set attitude without any control input.
Trim Tab
A small auxiliary hinged portion of a movable control surface that can be adjusted during flight to a position resulting in a balance of control forces.
Triple Spool Engine
Usually a turbofan engine design where the fan is the N1 compressor, followed by the N2 intermediate compressor, and the N3 high pressure compressor, all of which rotate on separate shafts at different speeds.
Tropical air
An air mass with characteristics developed over low latitudes. Maritime tropical air (mT), the principal type, is produced over the tropical and subtropical seas; very warm and humid. Continental tropical (cT) is produced over subtropical arid regions and is hot and very dry. Compare polar air.
Tropical cyclone
A general term for a cyclone that originates over tropical oceans. By international agreement, tropical cyclones have been classified according to their intensity, as follows: (1) tropical depression-winds up to 34 knots (64 km/h); (2) tropical storm-winds of 35 to 64 knots (65 to 119 km/h); (3) hurricane or typhoon-winds of 65 knots or higher (120 km/h).
Tropical depression
A cyclone that originates over tropical oceans. A tropical depression winds up to 34 knots (64 km/h).
Tropical storm
A cyclone that originates over tropical oceans. A tropical storm has winds of 35 to 64 knots (65 to 119 km/h).
Tropopause
The boundary layer between the troposphere and the mesosphere which acts as a lid to confine most of the water vapor, and the associated weather, to the troposphere.
Troposphere
The layer of the atmosphere extending from the surface to a height of 20,000 to 60,000 feet depending on latitude.
Trough (also called trough line)
In meteorology, an elongated area of relatively low atmospheric pressure; usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow (isobars, contours, or streamlines); compare with ridge.
TRSA Service
This service provides, in addition to basic radar service, sequencing of all IFR and participating VFR aircraft to the primary airport and separation between all participating VFR aircraft. The purpose of this service is to provide separation between all participating VFR aircraft and all IFR aircraft operating within the area defined as a TRSA.
True airspeed
Actual airspeed, determined by applying a correction for pressure altitude and temperature to the CAS.
True Airspeed (TAS)
Calibrated airspeed corrected for altitude and nonstandard temperature. Because air density decreases with an increase in altitude, an airplane has to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure. Therefore, for a given calibrated airspeed, true airspeed increases as altitude increases; or for a given true airspeed, calibrated airspeed decreases as altitude increases.
True Altitude
The vertical distance of the airplane above sea level—the actual altitude. It is often expressed as feet above mean sea level (MSL). Airport, terrain, and obstacle elevations on aeronautical charts are true altitudes.
True Course
A predetermined desired course direction to be followed (measured in degrees from true north).
True wind direction
The direction, with respect to true north, from which the wind is blowing.
True-false test item
A test item consisting of a statement followed by an opportunity for the student to determine whether the statement is true or false.
Truss
A fuselage design made up of supporting structural members that resist deformation by applied loads. The truss-type fuselage is constructed of steel or aluminum tubing. Strength and rigidity is achieved by welding the tubing together into a series of triangular shapes, called trusses.
Turbine Blades
The portion of the turbine assembly that absorbs the energy of the expanding gases and converts it into rotational energy.
Turbine discharge pressure
The total pressure at the discharge of the low-pressure turbine in a dual-turbine axial-flow engine.
Turbine engine
An aircraft engine which consists of an air compressor, a combustion section, and a turbine. Thrust is produced by increasing the velocity of the air flowing through the engine.
Turbine Outlet Temperature (TOT)
The temperature of the gases as they exit the turbine section.
Turbine Plenum
The portion of the combustor where the gases are collected to be evenly distributed to the turbine blades.
Turbine Rotors
The portion of the turbine assembly that mounts to the shaft and holds the turbine blades in place.
Turbine Section
The section of the engine that converts high pressure high temperature gas into rotational energy.
Turbocharger
An air compressor driven by exhaust gases, which increases the pressure of the air going into the engine through the carburetor or fuel injection system.
Turbofan Engine
A turbojet engine in which additional propulsive thrust is gained by extending a portion of the compressor or turbine blades outside the inner engine case. The extended blades propel bypass air along the engine axis but between the inner and outer casing. The air is not combusted but does provide additional thrust.
Turbojet Aircraft
An aircraft having a jet engine in which the energy of the jet operates a turbine which in turn operates the air compressor.
Turbojet Engine
A jet engine incorporating a turbine-driven air compressor to take in and compress air for the combustion of fuel, the gases of combustion being used both to rotate the turbine and create a thrust producing jet.
Turboprop Aircraft
An aircraft having a jet engine in which the energy of the jet operates a turbine which drives the propeller.
Turboprop Engine
A turbine engine that drives a propeller through a reduction gearing arrangement. Most of the energy in the exhaust gases is converted into torque, rather than its acceleration being used to propel the aircraft.
Turboshaft engine
A gas turbine engine that delivers power through a shaft to operate something other than a propeller.
Turbulence
An occurrence in which a flow of fluid is unsteady.
Turn Anticipation
The capability of RNAV systems to determine the point along a course, prior to a turn WP, where a turn should be initiated to provide a smooth path to intercept the succeeding course, and to enunciate the information to the pilot.
Turn Coordinator
A rate gyro that senses both roll and yaw due to the gimbal being canted. Has largely replaced the turn-and-slip indicator in modern aircraft.
Turn WP [Turning Point]
A WP which identifies a change from one course to another.
Turn-And-Slip Indicator
A flight instrument consisting of a rate gyro to indicate the rate of yaw and a curved glass inclinometer to indicate the relationship between gravity and centrifugal force. The turn-and-slip indicator indicates the relationship between angle of bank and rate of yaw. Also called a turn-and-bank indicator.
Turning Error
One of the errors inherent in a magnetic compass caused by the dip compensating weight. It shows up only on turns to or from northerly headings in the Northern Hemisphere and southerly headings in the Southern Hemisphere. Turning error causes the compass to lead turns to the north or south and lag turns away from the north or south.
Twilight
The intervals of incomplete darkness following sunset and preceding sunrise. The time at which evening twilight ends or morning twilight begins is determined by arbitrary convention, and several kinds of twilight have been defined and used; most commonly civil, nautical, and astronomical twilight.
Twister
In the United States, a colloquial term for tornado.
Two-Way Radio Communications Failure
Lost Communications.
Type
(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, a specific make and basic model of aircraft, including modifications thereto that do not change its handling or flight characteristics. Examples include: DC–7, 1049, and F–27; and
(2) As used with respect to the certification of aircraft, those aircraft which are similar in design. Examples include: DC–7 and DC–7C; 1049G and 1049H; and F–27 and F–27F.
(3) As used with respect to the certification of aircraft engines, those engines which are similar in design. For example, JT8D and JT8D–7 are engines of the same type, and JT9D–3A and JT9D–7 are engines of the same type.
Type Certificate Data Sheets (TCDS)
The official specifications issued by the FAA for an aircraft, engine, or propeller.
Typhoon
A tropical cyclone in the Eastern Hemisphere with winds in excess of 65 knots (120 km/h).
Ultimate Load Factor
In stress analysis, the load that causes physical breakdown in an aircraft or aircraft component during a strength test, or the load that according to computations, should cause such a breakdown.
Ultra-high frequency (UHF)
The range of electromagnetic frequencies between 962 MHz and 1213 MHz.
Ultrahigh Frequency
The frequency band between 300 and 3,000 MHz. The bank of radio frequencies used for military air/ground voice communications. In some instances this may go as low as 225 MHz and still be referred to as UHF.
Ultralight Vehicle
An aeronautical vehicle operated for sport or recreational purposes which does not require FAA registration, an airworthiness certificate, nor pilot certification. They are primarily single occupant vehicles, although some two-place vehicles are authorized for training purposes. Operation of an ultralight vehicle in certain airspace requires authorization from ATC.
Unable
Indicates inability to comply with a specific instruction, request, or clearance.
Unassociated
A radar target that does not display a data block with flight identification and altitude information.
Uncaging
Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.
Uncontrolled airspace
Class G airspace that has not been designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control air traffic; however, pilots should remember there are VFR minimums which apply to this airspace.
Under The Hood
Indicates that the pilot is using a hood to restrict visibility outside the cockpit while simulating instrument flight. An appropriately rated pilot is required in the other control seat while this operation is being conducted.
Undercast
A cloud layer of ten-tenths (1.0) coverage (to the nearest tenth) as viewed from an observation point above the layer.
Underpower
Using less power than required for the purpose of achieving a faster rate of airspeed change.
Understanding
A basic level of learning at which a student comprehends or grasps the nature or meaning of something.
Undrainable Oil
Oil that does not drain from an engine lubricating system when the aircraft is in the normal ground attitude and the drain valve is left open. The weight of the undrainable oil is part of the empty weight of the aircraft.
Unfeathering Accumulator
Tanks that hold oil under pressure which can be used to unfeather a propeller.
Unfrozen
The Scheduled Time of Arrival (STA) tags, which are still being rescheduled by traffic management advisor (TMA) calculations. The aircraft will remain unfrozen until the time the corresponding estimated time of arrival (ETA) tag passes the preset freeze horizon for that aircraft’s stream class. At this point the automatic rescheduling will stop, and the STA becomes “frozen.”
UNICOM
A non-government air/ground radio communication station which may provide airport information at public use airports where there is no tower or FSS.
United States
In a geographical sense means (1) the States, the District of Columbia, Puerto Rico, and the possessions, including the territorial waters, and (2) the airspace of those areas.
United States air carrier
A citizen of the United States who undertakes directly by lease, or other arrangement, to engage in air transportation.
United States Terminal Procedures Publication (TPP)
Booklets published in regional format by the NACO that include DPs, STARs, IAPs, and other information pertinent to IFR flight.
United States Terminal Procedures Publication (TPP).
Booklets published in regional format by the NACO that include DPs, STARs, IAPs, and other information pertinent to IFR flight.
Unlimited ceiling
A clear sky or a sky cover that does not meet the criteria for a ceiling.
Unpublished Route
A route for which no minimum altitude is published or charted for pilot use. It may include a direct route between NAVAIDs, a radial, a radar vector, or a final approach course beyond the segments of an instrument approach procedure.
Unreliable (GPS/WAAS)
An advisory to pilots indicating the expected level of service of the GPS and/or WAAS may not be available. Pilots must then determine the adequacy of the signal for desired use.
Unstable
Instability. A general term to indicate various states of the atmosphere in which spontaneous convection will occur when prescribed criteria are met; indicative of turbulence.
Unusable Fuel
Fuel that cannot be consumed by the engine. This fuel is considered part of the empty weight of the aircraft.
Unusual attitude
An unintentional, unanticipated, or extreme aircraft attitude.
Updraft
A localized upward current of air.
Upper front
A front aloft not extending to the earth’s surface.
Upslope fog
Fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its initial dew point.
Upwind Leg
A flight path parallel to the landing runway in the direction of landing.
Urgency
A condition of being concerned about safety and of requiring timely but not immediate assistance; a potential distress condition.
Urgency [ICAO]
A condition concerning the safety of an aircraft or other vehicle, or of person on board or in sight, but which does not require immediate assistance.
Usability
The functionality of tests.
Usable Fuel
(GAMA) Fuel available for flight planning.
Useful Load
The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.
User Request Evaluation Tool (URET)
The URET helps provide enhanced, automated flight data management. URET is an automated tool provided at each radar position in selected en route facilities. It uses flight and radar data to determine present and future trajectories for all active and proposed aircraft flights. A graphic plan display depicts aircraft, traffic, and notification of predicted conflicts. Graphic routes for current plans and trial plans are displayed upon controller request. URET can generate a predicted conflict of two aircraft, or between aircraft and airspace.
User-defined Waypoint
User-defined waypoints typically are created by pilots for use in their own random RNAV direct navigation. They are newly established, unpublished airspace fixes that are designated geographic locations/positions that help provide positive course guidance for navigation and a means of checking progress on a flight. They may or may not be actually plotted by the pilot on enroute charts, but would normally be communicated to ATC in terms of bearing and distance or latitude/longitude. An example of user defined waypoints typically includes those derived from database-driven area navigation (RNAV) systems whereby latitude/longitude coordinate-based waypoints are generated by various means including keyboard input, and even electronic map mode functions used to establish waypoints with a cursor on the display. Another example is an offset phantom waypoint, which is a point in space formed by a bearing and distance from NAVAIDs such as VORs, VORTACs, and TACANs, using a variety of navigation systems.
User-defined waypoints
Waypoint location and other data which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.
Utility Category
An airplane that has a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for limited acrobatic operation.
V-Bars
The flight director displays on the attitude indicator that provide control guidance to the pilot.
V-G Diagram
A chart that relates velocity to load factor. It is valid only for a specific weight, configuration, and altitude and shows the maximum amount of positive or negative lift the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds.
V-Speeds
Designated speeds for a specific flight condition.
V-Tail
A design which utilizes two slanted tail surfaces to perform the same functions as the surfaces of a conventional elevator and rudder configuration. The fixed surfaces act as both horizontal and vertical stabilizers.
Valid Non-Alert
A situation in which the safety logic software correctly determines that an alert is not required, based upon the design specifications and the current set of Safety Logic parameters.
Validity
The extent to which a test measures what it is supposed to measure.
Vapor Lock
A condition in which air enters the fuel system and it may be difficult, or impossible, to restart the engine. Vapor lock may occur as a result of running a fuel tank completely dry, allowing air to enter the fuel system. On fuel-injected engines, the fuel may become so hot it vaporizes in the fuel line, not allowing fuel to reach the cylinders.
Vapor pressure
In meteorology, the pressure of water vapor in the atmosphere. Vapor pressure is that part of the total atmospheric pressure due to water vapor and is independent of the other atmospheric gases or vapors.
Vapor trail
Same as condensation trail—a cloud-like streamer frequently observed to form behind aircraft flying in clear, cold, humid air.
Variation
Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
Vector
A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.
Vectoring
Navigational guidance by assigning headings.
Veering
Shifting of the wind in a clockwise direction with respect to either space or time; opposite of backing. Commonly used by meteorologists to refer to an anticyclonic shift (clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere).
Velocity
The speed or rate of movement in a certain direction.
Venturi tube
A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.
Verify
Request confirmation of information; e.g., “verify assigned altitude.”
Verify Specific Direction Of Takeoff (Or Turns After Takeoff)
Used by ATC to ascertain an aircraft’s direction of takeoff and/or direction of turn after takeoff. It is normally used for IFR departures from an airport not having a control tower. When direct communication with the pilot is not possible, the request and information may be relayed through an FSS, dispatcher, or by other means.
Vertex
The last fix adapted on the arrival speed segments. Normally, it will be the outer marker of the runway in use. However, it may be the actual threshold or other suitable common point on the approach path for the particular runway configuration.
Vertex Time Of Arrival
A calculated time of aircraft arrival over the adapted vertex for the runway configuration in use. The time is calculated via the optimum flight path using adapted speed segments.
Vertical Axis
An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.
Vertical Card Compass
A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.
Vertical Navigation (VNAV)
Traditionally, the only way to get glidepath information during an approach was to use a ground-based NAVAID, but modern area navigation systems allow flight crews to display an internally generated descent path that allows a constant rate descent to minimums during approaches that would otherwise include multiple level-offs.
Vertical Navigation Planning
Included within certain STARs is information provided to help you reduce the amount of low altitude flying time for high performance aircraft, like jets and turboprops. An expected altitude is given for a key fix along the route. By knowing an intermediate altitude in advance when flying a high performance aircraft, you can plan the power or thrust settings and aircraft configurations that result in the most efficient descent, in terms of time, fuel requirements, and engine wear.
Vertical Separation
Separation established by assignment of different altitudes or flight levels.
Vertical Separation [ICAO]
Separation between aircraft expressed in units of vertical distance.
Vertical Speed Indicator (VSI)
An instrument that uses static pressure to display a rate of climb or descent in feet per minute. The VSI can also sometimes be called a vertical velocity indicator (VVI).
Vertical Stability
Stability about an aircraft’s vertical axis. Also called yawing or directional stability.
Vertical Takeoff And Landing Aircraft
Aircraft capable of vertical climbs and/or descents and of using very short runways or small areas for takeoff and landings. These aircraft include, but are not limited to, helicopters.
Vertical visibility
The distance one can see upward into a surface based obscuration; or the maximum height from which a pilot in flight can recognize the ground through a surface based obscuration.
Very High Frequency
The frequency band between 30 and 300 MHz. Portions of this band, 108 to 118 MHz, are used for certain NAVAIDs; 118 to 136 MHz are used for civil air/ground voice communications. Other frequencies in this band are used for purposes not related to air traffic control.
Very High Frequency Omnidirectional Range Station
VOR.
Very Low Frequency
The frequency band between 3 and 30 kHz.
Very-high frequency (VHF)
A band of radio frequencies falling between 30 and 300 MHz.
Very-high frequency omnidirectional range (VOR)
Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.
Very-high frequency omnidirectional range (VOR).
Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.
Vestibule
The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.
VFR Aircraft
An aircraft conducting flight in accordance with visual flight rules.
VFR Conditions
Weather conditions equal to or better than the minimum for flight under visual flight rules. The term may be used as an ATC clearance/instruction only when: a. An IFR aircraft requests a climb/descent in VFR conditions. b. The clearance will result in noise abatement benefits where part of the IFR departure route does not conform to an FAA approved noise abatement route or altitude. c. A pilot has requested a practice instrument approach and is not on an IFR flight plan. Note: All pilots receiving this authorization must comply with the VFR visibility and distance from cloud criteria in 14 CFR Part 91. Use of the term does not relieve controllers of their responsibility to separate aircraft in Class B and Class C airspace or TRSAs as required by FAAO JO 7110.65. When used as an ATC clearance/instruction, the term may be abbreviated “VFR;” e.g., “MAINTAIN VFR,” “CLIMB/DESCEND VFR,” etc.
VFR Flight
VFR Aircraft.
VFR Military Training Routes
Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training under VFR below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.
VFR Not Recommended
An advisory provided by a flight service station to a pilot during a preflight or inflight weather briefing that flight under visual flight rules is not recommended. To be given when the current and/or forecast weather conditions are at or below VFR minimums. It does not abrogate the pilot’s authority to make his/her own decision.
VFR on top
ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.
VFR over the top
A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
VFR over-the-top
A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
VFR terminal area chart
At a scale of 1:250,000, a chart that depicts Class B airspace, which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
VFR Terminal Area Charts
Aeronautical Chart.
VFR Terminal Area Charts (1:250,000)
Depict Class B airspace which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information which includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
VFR Waypoint
Waypoint.
VFR-on-top
ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.
VHF Omnidirectional Range/Tactical Air Navigation
VORTAC.
Victor airways
Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas. Visual approach slope indicator (VASI). A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glide slope will see red lights over white lights.
Video Map
An electronically displayed map on the radar display that may depict data such as airports, heliports, runway centerline extensions, hospital emergency landing areas, NAVAIDs and fixes, reporting points, airway/route centerlines, boundaries, handoff points, special use tracks, obstructions, prominent geographic features, map alignment indicators, range accuracy marks, minimum vectoring altitudes.
Virga
Water or ice particles falling from a cloud, usually in wisps or streaks, and evaporating before reaching the ground.
Virtual Reality (VR)
A form of computer-based technology that creates a sensory experience allowing a participant to believe and barely distinguish a virtual experience from a real one. VR uses graphics with animation systems, sounds, and images to reproduce electronic versions of real-life experience.
Visibility
The greatest distance one can see and identify prominent objects.
Visibility [ICAO]
The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.
Visual Approach
A visual approach is an ATC authorization for an aircraft on an IFR flight plan to proceed visually to the airport of intended landing; it is not an IAP. Also, there is no missed approach segment. When it is operationally beneficial, ATC may authorize pilots to conduct a visual approach to the airport in lieu of the published IAP. A visual approach can be initiated by a pilot or the controller.
Visual Approach Slope Indicator
Airport Lighting.
Visual Approach Slope Indicator (VASI)
The most common visual glidepath system in use. The VASI provides obstruction clearance within 10° of the extended runway centerline, and to 4 nautical miles (NM) from the runway threshold.
Visual Approach [ICAO]
An approach by an IFR flight when either part or all of an instrument approach procedure is not completed and the approach is executed in visual reference to terrain.
Visual Climb Over Airport (VCOA)
A departure option for an IFR aircraft, operating in visual meteorological conditions equal to or greater than the specified visibility and ceiling, to visually conduct climbing turns over the airport to the published “climb-to” altitude from which to proceed with the instrument portion of the departure. VCOA procedures are developed to avoid obstacles greater than 3 statute miles from the departure end of the runway as an alternative to complying with climb gradients greater than 200 feet per nautical mile. These procedures are published in the `Take-Off Minimums and (Obstacle) Departure Procedures’ section of the Terminal Procedures Publications.
Visual Climb Over the Airport (VCOA)
An option to allow an aircraft to climb over the airport with visual reference to obstacles to attain a suitable altitude from which to proceed with an IFR departure.
Visual Descent Point
A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot.
Visual descent point (VDP)
A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the runway environment is clearly visible to the pilot.
Visual Flight Rules
Rules that govern the procedures for conducting flight under visual conditions. The term “VFR” is also used in the United States to indicate weather conditions that are equal to or greater than minimum VFR requirements. In addition, it is used by pilots and controllers to indicate type of flight plan.
Visual Flight Rules (VFR)
Code of Federal Regulations that govern the procedures for conducting flight under visual conditions.
Visual Holding
The holding of aircraft at selected, prominent geographical fixes which can be easily recognized from the air.
Visual Meteorological Conditions
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling equal to or better than specified minima.
Visual meteorological conditions (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
Visual range
Runway visual range. An instrumentally derived horizontal distance a pilot should see down the runway from the approach end; based on either the sighting of high intensity runway lights or on the visual contrast of other objects, whichever yields the greatest visual range.
Visual Segment
Published Instrument Approach Procedure Visual Segment.
Visual Separation
A means employed by ATC to separate aircraft in terminal areas and en route airspace in the NAS. There are two ways to effect this separation: a. The tower controller sees the aircraft involved and issues instructions, as necessary, to ensure that the aircraft avoid each other. b. A pilot sees the other aircraft involved and upon instructions from the controller provides his/her own separation by maneuvering his/her aircraft as necessary to avoid it. This may involve following another aircraft or keeping it in sight until it is no longer a factor.
Voice Switching And Control System
The VSCS is a computer controlled switching system that provides air traffic controllers with all voice circuits (air to ground and ground to ground) necessary for air traffic control.
VOR test facility (VOT)
A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, while others are limited to ground use only.
VOR Test Signal
A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, and others are limited to ground use only.
Vortex
In meteorology, any rotary flow in the atmosphere.
Vortices
Circular patterns of air created by the movement of an airfoil through the air when generating lift. As an airfoil moves through the atmosphere in sustained flight, an area of area of low pressure is created above it. The air flowing from the high pressure area to the low pressure area around and about the tips of the airfoil tends to roll up into two rapidly rotating vortices, cylindrical in shape. These vortices are the most predominant parts of aircraft wake turbulence and their rotational force is dependent upon the wing loading, gross weight, and speed of the generating aircraft. The vortices from medium to heavy aircraft can be of extremely high velocity and hazardous to smaller aircraft.
Vorticity
Turning of the atmosphere. Vorticity may be imbedded in the total flow and not readily identified by a flow pattern. Types are: absolute, negative, positive, and relative vorticity.
Vs1
The stalling speed or the minimum steady flight speed obtained in a specified configuration. For most airplanes, this is the power-off stall speed at the maximum takeoff weight in the clean configuration (gear up, if retractable, and flaps up). The lower limit of the green arc.
Vso
The stalling speed or the minimum steady flight speed in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down). The lower limit of the white arc.
VTOL Aircraft
Vertical Takeoff And Landing Aircraft.
Vx
Best angle-of-climb speed. The airspeed at which an airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.
Vy
Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.
Vyse
Best rate-of-climb speed with one engine inoperative. This airspeed provides the most altitude gain in a given period of time in a light, twin-engine airplane following an engine failure.
Wake Turbulence
Wingtip vortices that are created when an airplane generates lift. When an airplane generates lift, air spills over the wingtips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices or wake turbulence.
Wall cloud
The well-defined bank of vertically developed clouds having a wall-like appearance which form the outer boundary of the eye of a well-developed tropical cyclone.
Warm front
Any non-occluded front which moves in such a way that warmer air replaces colder air.
Warm sector
The area covered by warm air at the surface and bounded by the warm front and cold front of a wave cyclone.
Warning area
An area containing hazards to any aircraft not participating in the activities being conducted in the area. Warning areas may contain intensive military training, gunnery exercises, or special weapons testing.
Waste Gate
A controllable valve in the tailpipe of an aircraft reciprocating engine equipped with a turbocharger. The valve is controlled to vary the amount of exhaust gases forced through the turbocharger turbine.
Water equivalent
The depth of water that would result from the melting of snow or ice.
Water vapor
Water in the invisible gaseous form.
Waterspout
A tornado that forms over water.
Wave cyclone
A cyclone which forms and moves along a front. The circulation about the cyclone center tends to produce a wavelike deformation of the front.
Waypoint
A designated geographical location used for route definition or progress-reporting purposes and is defined in terms of latitude/longitude coordinates.
Waypoint (WP)
A predetermined geographical position used for route/instrument approach definition, progress reports, published VFR routes, visual reporting points or points for transitioning and/or circumnavigating controlled and/or special use airspace, that is defined relative to a VORTAC station or in terms of latitude/longitude coordinates.
Waypoints
Area navigation waypoints are specified geographical locations, or fixes, used to define an area navigation route or the flight path of an aircraft employing area navigation. Waypoints may be any of the following types:predefined, published, floating, user-defined, fly-by, or fly-over.
Weather
The state of the atmosphere, mainly with respect to its effects on life and human activities; refers to instantaneous conditions or short term changes as opposed to climate.
Weather Advisory
In aviation weather forecast practice, an expression of hazardous weather conditions not predicted in the area forecast, as they affect the operation of air traffic and as prepared by the NWS.
Weather and radar processor (WARP)
A device that provides real-time, accurate, predictive and strategic weather information presented in an integrated manner in the National Airspace System (NAS).
Weather depiction chart
Details surface conditions as derived from METAR and other surface observations.
Weather radar
Radar specifically designed for observing weather. Some types are cloud detection radar and storm detection radar.
Weather vane
A wind vane.
Weathervane
The tendency of the aircraft to turn into the relative wind.
Wedge
Same as ridge—an elongated area of relatively high atmospheric pressure; usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow (isobars, contours, or streamlines).
Weight
A measure of the heaviness of an object. The force by which a body is attracted toward the center of the Earth (or another celestial body) by gravity. Weight is equal to the mass of the body times the local value of gravitational acceleration. One of the four main forces acting on an aircraft. Equivalent to the actual weight of the aircraft. It acts downward through the aircraft’s center of gravity toward the center of the Earth. Weight opposes lift.
Weight And Balance
The aircraft is said to be in weight and balance when the gross weight of the aircraft is under the max gross weight, and the center of gravity is within limits and will remain in limits for the duration of the flight.
Weight-shift-control aircraft
A powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity with respect to the wing. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than the use of control surfaces.
Wet bulb
Contraction of either wet-bulb temperature or wet-bulb thermometer.
Wet-bulb temperature
The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air, by evaporation of water (or ice) from the muslin wick; used in computing dew point and relative humidity.
Wet-bulb thermometer
A thermometer with a muslin-covered bulb used to measure wet-bulb temperature.
Wheelbarrowing
A condition caused when forward yoke or stick pressure during takeoff or landing causes the aircraft to ride on the nosewheel alone.
When Able
When used in conjunction with ATC instructions, gives the pilot the latitude to delay compliance until a condition or event has been reconciled. Unlike “pilot discretion,” when instructions are prefaced “when able,” the pilot is expected to seek the first opportunity to comply. Once a maneuver has been initiated, the pilot is expected to continue until the specifications of the instructions have been met. “When able,” should not be used when expeditious compliance is required.
Whirlwind
A small, rotating column of air; may be visible as a dust devil.
Wide Area Augmentation System (WAAS)
A method of navigation based on GPS. Ground correction stations transmit position corrections that enhance system accuracy and add vertical navigation (VNAV) features.
Wide-Area Augmentation System (WAAS)
The WAAS is a satellite navigation system consisting of the equipment and software which augments the GPS Standard Positioning Service (SPS). The WAAS provides enhanced integrity, accuracy, availability, and continuity over and above GPS SPS. The differential correction function provides improved accuracy required for precision approach.
Wilco
I have received your message, understand it, and will comply with it.
Willy-willy
A tropical cyclone of hurricane strength near Australia.
Wind
Air in motion relative to the surface of the earth; generally used to denote horizontal movement.
Wind Correction Angle
Correction applied to the course to establish a heading so that track will coincide with course.
Wind correction angle (WCA)
The angle between the desired track and the heading of the aircraft necessary to keep the aircraft tracking over the desired track.
Wind direction
The direction from which wind is blowing.
Wind Direction Indicators
Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.
Wind Grid Display
A display that presents the latest forecasted wind data overlaid on a map of the ARTCC area. Wind data is automatically entered and updated periodically by transmissions from the National Weather Service. Winds at specific altitudes, along with temperatures and air pressure can be viewed.
Wind Shear
A sudden, drastic shift in windspeed, direction, or both that may occur in the horizontal or vertical plane.
Wind speed
Rate of wind movement in distance per unit time.
Wind vane
An instrument to indicate wind direction.
Wind velocity
A vector term to include both wind direction and wind speed.
Windmilling
When the air moving through a propeller creates the rotational energy.
Winds and temperature aloft forecast (FD)
A twice daily forecast that provides wind and temperature forecasts for specific locations in the contiguous United States.
Windsock
A truncated cloth cone open at both ends and mounted on a freewheeling pivot that indicates the direction from which the wind is blowing.
Wing
Airfoil attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.
Wing Area
The total surface of the wing (square feet), which includes control surfaces and may include wing area covered by the fuselage (main body of the airplane), and engine nacelles.
Wing Chord
A straight-line distance across a wing from leading edge to trailing edge.
Wing Span
The maximum distance from wingtip to wingtip.
Wing Tank Liner
A liner for aircraft fuel tanks which limits the amount of fuel that can be spilled in the event of a crash.
Wing Tip Vortices
Vortices.
Wing Twist
A design feature incorporated into some wings to improve aileron control effectiveness at high angles of attack during an approach to a stall.
Winglet or tip fin
An out-of-plane surface extending from a lifting surface. The surface may or may not have control surfaces.
Wings
Airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.
Wingtip Vortices
The rapidly rotating air that spills over an airplane’s wings during flight. The intensity of the turbulence depends on the airplane’s weight, speed, and configuration. It is also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.
Words Twice
A. As a request: “Communication is difficult. Please say every phrase twice.”
B. As information: “Since communications are difficult, every phrase in this message will be spoken twice.”
Work
A measurement of force used to produce movement.
Working or short-term memory
The portion of the brain that receives information from the sensory register. This portion of the brain can store information in memory for only a short period of time. If the information is determined by an individual to be important enough to remember, it must be coded in some way for transmittal to long-term memory.
World Aeronautical Charts
Aeronautical Chart.
World Aeronautical Charts (WAC)
A standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation (1:1,000,000) by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions and other pertinent data. Discontinued on June 25, 2015
World Aeronautical Charts (WAC) (1:1,000,000)
Provide a standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions, and other pertinent data. Discontinued.
Yaw
Rotation about the vertical axis of an aircraft.
Yaw String
A string on the nose or windshield of an aircraft in view of the pilot that indicates any slipping or skidding of the aircraft.
Zero Fuel Weight
The weight of the aircraft to include all useful load except fuel.
Zero Sideslip
A maneuver in a twin-engine airplane with one engine inoperative that involves a small amount of bank and slightly uncoordinated flight to align the fuselage with the direction of travel and minimize drag.
Zero Thrust (Simulated Feather)
An engine configuration with a low power setting that simulates a propeller feathered condition.
Zonal wind
A west wind; the westerly component of a wind. Conventionally used to describe large-scale flow that is neither cyclonic nor anticyclonic.
Zone of confusion
Volume of space above the station where a lack of adequate navigation signal directly above the VOR station causes the needle to deviate.Warning area. An area containing hazards to any aircraft not participating in the activities being conducted in the area. Warning areas may contain intensive military training, gunnery exercises, or special weapons testing.
Zulu time
A term used in aviation for coordinated universal time (UTC) which places the entire world on one time standard.
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