Glossary  A  14 CFR.  See Title 14 of the Code of Federal Regulations.  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 accuracy.  The ability to determine present position  in space independently, and is most often used by pilots.  Absolute altitude.  The actual distance between an aircraft  and the terrain over which it is flying.  Absolute pressure.  Pressure measured from the reference  of zero pressure, or a vacuum.  A.C.  Alternating current.  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.  Accelerate-go distance.  The distance required to accelerate  to V$_{1}$ with all engines at takeoff power, experience an engine  failure at V$_{1}$, and continue the takeoff on the remaining  engine(s). The runway required includes the distance required  to climb to 35 feet by which time V$_{2}$ speed must be attained.  Accelerate-stop distance.  The distance required to accelerate  to V$_{1}$ with all engines at takeoff power, experience an engine  failure at V$_{1}$, and abort the takeoff and bring the airplane to  a stop using braking action only (use of thrust reversing is  not considered).  Accelerometer.  A part of an inertial navigation system  (INS) that accurately measures the force of acceleration in  one direction.  ADC.  See air data computer.  ADF.  See automatic direction finder.  ADI.  See attitude director indicator.  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.  ADM.  See aeronautical decision-making.  ADS-B.  See automatic dependent surveillance-broadcast.  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.  G-1 