AERONAUTICAL GLOSSARY

100-HOUR INSPECTION — An inspection, identical in scope to an annual inspection. Conducted every 100 hours of flight on aircraft of under 12,500 pounds that are used to carry passengers for hire.

ABSOLUTE ALTITUDE—The vertical distance of an airplane above the terrain, or above ground level (AGL).

ACCELERATION—Force involved in overcoming inertia, and which may be defined as a change in velocity per unit of time.

ACCELERATION ERROR — Fluctuation of the magnetic compass during acceleration. In the Northern Hemisphere, the compass swings toward the north during acceleration.

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 include 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).

ADF— See AUTOMATIC DIRECTION FINDER.

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.

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.

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.

ADVECTION FOG—Fog resulting from the movement of warm, humid air over a cold surface.

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.

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 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 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.

AGONIC LINE—Line along which the variation between true and magnetic values is zero.