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Aviation Terminology – 0 to Ai

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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 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.

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.

ADL.   See attitude director indicator.

Adiabatic cooling.  A process of cooling 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.  Sometime 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.

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.

A/FD.  See Airport/Facility Directory.

Agonic line.  Anb 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.

Aircraft.  A device that is used, or intended to be used, for flight.

Aircraft altitude.  The actual height above sea level at which the aircraft is flying.

Aircraft approach category.  A performance grouping of aircraft based on a speed of 1.3 times the stall speed in the landing configuration at maximum gross landing weight.

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.

Airfoil.  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.

Air mass.  An extensive body of air having fairly uniform properties of temperature and moisture.

AIRMET.  In flight weather issued as an amendment to the area forecast, concerning weather phenomena of operational interest to all aircraft and that is potentially hazardous to aircraft with limited capability due to lack of equipment, instrumentation, or pilot qualifications.

Airplane.  An engine-driven, fixed wing aircraft heavier than air that is supported in flight by the dynamic reaction of 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 by substituted for the AFM/POH.

Airport diagram.  The section of an instrument approach procedure chart that shows a detailed diagram of the airport.  This diagram includes surface features and airport configuration information.

Airport/Facility Directory (A/FD).  An FAA publication containing information on all airports, communications, and NAVAIDs.

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 (ASR).  Approach control radar used to detect and display an aircraft’s 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 controller’s radar scope.

Air route traffic control center (ARTCC).  Provides ATC service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight.

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 craft’s airspeed, typically in knots, to the pilot.

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.

Airway.  An airway is based on a centerline that extends from one navigation aid or intersection to another navigation aid (or through several navigation ais or intersections); used to establish a known route for en route procedures between terminal areas.

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) are to be complied with within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance are recorded in the aircraft’s maintenance records.

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