Aviation Glossary - A

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a/c - aircraft.

A/D - aerodrome.

A/G - air-to-ground

A/P - airport or autopilot.

aae - above aerodrome elevation. Also see aal.

AAIB - Air Accident Investigation Branch of the Department of Transport.

aal - above aerodrome level. Also see aae.

ab initio - literally 'from the beginning', elementary flying training.

abm abeam - an aircraft is abeam a point when that point is at ninety degrees left or right of the aircraft's track, but term usually used to indicate a general position rather than a specific point.

AC - alternating current.

ACARS - Aircraft Communication Adressing and Reporting System.

ACC - Area Control Centre. And ACZ Aerodrome Control Zone. See ATZ below.

accelerate - stop distance- calculated distance required for an aircraft to accelerate to V1 (which see), reject take-off and brake safely to a halt.

ACMS - aircraft condition monitoring system.

ACR - aerodrome control radar.

AD - Airworthiness Directive, issued by airworthiness authorities to correct a defect found in an aircraft type after certification. Compliance is mandatory and may be required immediately and before further flight, within a specified period of time or number of flying hours, or when next due for routine maintenance.

ADA - Advisory aispace. Advisory Area or Advisory Route.

ADC - air data computer.

ADELT - automatically deployable emergency locator transmitter.

ADF - automatic direction finder/finding. Radio compass which gives a relative bearing to the non directional radio beacon to which it is tuned.

ADI - attitude deviation indicator. An advanced type of artificial horizon, part of a flight director system providing pitch and roll information and commands.

ADIZ - Air Defence Identification Zone. An area of airspace extending upwards from the surface, usually along a national boundary, within which identification of all aircraft is required in the interests of national security.

ADR - Accident Data Recorder.

ADS - Automatic Dependence Surveillance.

ADT - Approved Departure Time.

AEF - Aerodromes Environmental Federation.

Aerad - UK published flight guide and navigational chart system.

aerodrome/airport elevation - highest point of an aerodrome's usable runway(s) expressed in feet above mean sea level (amsl).

AEW - Airborne early warning

AFB - air force base, usually U.S. or Canadian.

AFCS - automatic flight control system, an advanced autopilot. Also IFCS, integrated flight control system.

AFDS - Autopilot and flight director system.

AFI - assistant flying instructor. Also AFIC, assistant flying instructor course, FIC, flying instructor course.

AFIS - Aerodrome Flight Information Service, providing information to, but not control of, aircraft using that aerodrome. Also AFISO, AFIS officer, and AGO, air-to-ground operator.

AFS - Aerodrome Fire Service.

AFS - Aeronautical Fixed Service telephone/teleprinter network, includes AFTN.

AFS - auto flight system.

AFTN - Aeronautical Fixed Telecommunications Network. A ground based teleprinter network transmitting flight plans, weather information etc.

agl - above ground level.

AHRS - attitude-heading reference system. A sensor deriving aircraft attitude and heading information from gyros and accelerometers.

AIAA - area of intense aerial activity, usually military.

AIC - Aeronautical Information Circular. Bulletins issued at intervals by the CAA relating to matters of airworthiness, administration, operating procedures, safety etc. AICs are colour-coded according to subject, e.g. safety circulars are pink, thus 'Pink 12' issued in December 1990

AIDS - Airborne integrated data system.

AIP - Aeronautical Information Publication. The UK Air Pilot, statutory bible of aeronautical information published by the CAA.

Airep - form for reporting position and Met conditions in flight.

Airmet - CAA's telephone aviation weather service, covering Southern, Northern and Scottish regions of the UK. Also Metdial and Metplan, privately-operated aviation weather services. For full details see Pilot, February 1991.

AIS - Aeronautical Information Service. CAA unit based at London Heathrow Airport, providing flight planning services and information for pilots. Publishes AICs, above.

AIZ - Aerodrome Information Zone.