Aeronautical Terms beginning with N
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.
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.
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.
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.
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.
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.
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.
Normalizing (Turbonormalizing)
A turbocharger that maintains sea level pressure in the induction manifold at altitude.
National Airspace System (NAS)
The common network of United States 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.
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 Route Program (NRP)
A set of rules and procedures designed to increase the flexibility of user flight planning within published guidelines.
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.
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.
Nondirectional radio beacon (NDB)
A ground-based radio transmitter that transmits radio energy in all directions.
Nonprecision approach
A standard instrument approach procedure in which only horizontal guidance is provided.
No procedure turn (NoPT)
Term used with the appropriate course and altitude to denote that the procedure turn is not required.
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.
Navigate
To move between websites on the internet. Navigation is often accomplished by means of links or connections between sites.
Norm-referenced testing
System of testing in which students are ranked against the performance of other students.
National defense airspace
Airspace established by a regulation prescribed, or an order issued under, 49 U.S.C. 40103(b)(3).
Navigable airspace
Airspace at and above the minimum flight altitudes prescribed by or under this chapter, including airspace needed for safe takeoff and landing.
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.
Nonprecision approach procedure
A standard instrument approach procedure in which no electronic glide slope is provided.
Net Weight
The weight of the aircraft less the weight of any chocks or other devices used to hold the aircraft on the scales.
Normal Category
A category of aircraft certificated under 14 CFR part 23 and CAR part 3 that allows the maximum weight and CG range while restricting the maneuvers that are permitted.
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.
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.
Normal
In meteorology, the value of an element averaged for a given location over a period of years and recognized as a standard.
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.
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.
Nautical twilight
The period of time before sunrise and after sunset when the sun is not more than 12° below the horizon.
Negative vorticity
Vorticity caused by anticyclonic turning; it is associated with downward motion of the air.
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 Airspace System (NAS)
The common network of United States 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.
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 Route Program (NRP)
A set of rules and procedures designed to increase the flexibility of user flight planning within published guidelines.
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.
Negative static stability
The initial tendency of an aircraft to continue away from the original state of equilibrium after being disturbed.
Neutral static stability
The initial tendency of an aircraft to remain in a new condition after its equilibrium has been disturbed.
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.
Nondirectional radio beacon (NDB)
A ground-based radio transmitter that transmits radio energy in all directions.
Nonprecision approach
A standard instrument approach procedure in which only horizontal guidance is provided.
No procedure turn (NoPT)
Term used with the appropriate course and altitude to denote that the procedure turn is not required.
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.