Aeronautical Terms beginning with B
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.
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.
Basic Empty Weight (GAMA)
Basic empty weight includes the standard empty weight plus optional and special equipment that has been installed.
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.
Blade Face
The flat portion of a propeller blade, resembling the bottom portion of an airfoil.
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.
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.
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.
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.
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.).
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.
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.
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.
Block altitude
A block of altitudes assigned by ATC to allow altitude deviations; for example, Maintain block altitude 9 to 11 thousand.
Basic need
A perception factor that describes a person’s ability to maintain and enhance the organized self.
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.
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.
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.
Briefing
An oral presentation where the speaker presents a concise array of facts without inclusion of extensive supporting material.
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.
Balloon
A lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.
Brake horsepower
The power delivered at the propeller shaft (main drive or main output) of an aircraft engine.
Balanced Laterally
Balanced in such a way that the wings tend to remain level.
Ballast
A weight installed or carried in an aircraft to move the center of gravity to a location within its allowable limits.
Basic Empty Weight
(GAMA) Standard empty weight plus optional equipment.
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.
Bilge Area
The lowest part of an aircraft structure in which water and contaminants collect.
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 (-).
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.
Banner cloud (also called cloud banner)
A banner-like cloud streaming off from a mountain peak.
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 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.
Beaufort scale
A scale of wind speeds.
Black blizzard
Same as dust storm—an unusual, frequently severe weather condition characterized by strong winds and dust-filled air over an extensive area.
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.
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.
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.
Buys Ballot’s law
If an observer in the Northern Hemisphere stands with his back to the wind, lower pressure is to his left.
Beam resolution
The ability of radar to distinguish between targets at approximately the same range but at different azimuths.
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.
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.
Baro-aiding
A method of augmenting the GPS integrity solution by using a nonsatellite input source. To ensure that baro-aiding is available, the current altimeter setting must be entered as described in the operating manual.
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.
Basic empty weight (GAMA)
Basic empty weight includes the standard empty weight plus optional and special equipment that has been installed.
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.
Biplanes
Airplanes with two sets of wings.
Block altitude
A block of altitudes assigned by ATC to allow altitude deviations; for example, “Maintain block altitude 9 to 11 thousand.”.
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.
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