ACMS - aircraft condition monitoring system.
ACR - aerodrome control radar.
accelerate-stop distance - calculated distance required for an aircraft to accelerate to V1 (which see), reject take-off and brake safely to a halt.
A/D - aerodrome.
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.
AEW - Airborne early warning
Aerad - UK-published flight guide and navigational chart system.
aerodrome/airport elevation - highest point of an aerodrome\
in feet above mean sea level (amsl).
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.
AFIS(O)- Aerodrome Flight InＦＯＲＭation Service (Officer)
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.
AGO - air-to-ground operator
A/G - air-to-ground.
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 \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\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. See ATZ below.
ALERFA - alert phase of search-and-rescue procedure.
alt - altitude. Height above sea level.
alternate - aerodrome specified on a flight plan to which an aircraft chooses to divert if a landing at its intended destination is not possible (for reasons of poor weather, for example).
altimeter setting - barometric pressure reading in millibars, hectopascals or (in USA) inches of mercury (Hg) used to set a pressure altimeter\
AM - Amplitude modulation.
AME - authorized medical examiner. A doctor approved by the CAA (or foreign licensing authority) to conduct examinations for the issue or renewal of aircrew medical certificates.
amsl - above mean sea level (sometimes asl in USA).
anhedral - sloping down from root to tip. Opposite: dihedral.
ANO - Air Navigation Order. Statutory legal instrument defining the laws of air navigation, pilot licensing etc, in the UK. Other aviation legislation includes the Rules of the Air and Air Traffic regulations and the Air Navigation (General) Regulations
AoA - angle of attack. Also alpha, thus \
AOA - Airport Operators\
AOC - Air Operator\CAA and required by aircraft operators flying scheduled or charter public transport flights, including cargo, air-taxi and pleasure-flying work. Also Air Officer Commanding in RAF parlance.
AoE - airport of entry (usually in USA).
AOG - aircraft on ground, a term used to denote urgency when requesting spares or service from suppliers or manufacturers, meaning that the aircraft cannot fly again until the parts have been supplied.
AOPA - Aircraft Owners and Pilots Association.
A/P - airport or autopilot.
A & P - Airframe and Powerplant Mechanic (USA).
APA - Aerodromes Protection Agency, the federation of associations for the advancement of British general aviation facilities.
APHAZ - Aircraft Proximity Hazards Assessment Panel, which investigates near-miss reports filed by air traffic controllers (see also JAWG).
APP - Approach (control).
APU - auxiliary power unit. Large transport aircraft and some business jets have an APU, typically a small turbine, to provide power for engine-starting and for running systems when on the ground, obviating the need for external power or ground power unit, GPU.
ARB - Airworthiness Review Board.
ARCAL - aircraft radio control of aerodrome lighting.
Aresti - key shorthand notation system devised by Spaniard José L Aresti whereby aerobatic display routines or competition sequences can be drawn up on paper like a musical score. Now largely superseded by the simpler FAI Aerobatic Catalogue system.
ARINC - Aeronautical Radio Incorporated. A non-profit corporation owned by airlines to set standards for airline avionics and provide communications services.
ARP - aerodrome reference point.
articulated rotor - blades can flap, drag and feather.
ARV - air recreational vehicle.
ASDA - accelerate-stop distance available.
ASI - airspeed indicator, a flight instrument which measures the speed of an aircraft through the air.
ASR - altimeter setting region, a geographical area for which the lowest value of QNH is forecast hourly and relayed by air traffic control centres. Also airport surveillance radar and air-sea rescue.
ASTOVL - advanced short take-off and vertical landing.
ATA - actual time of arrival. Also Air Training Association.
ATC - air traffic control.
ATCA - air traffic control assistant
ATC(C) - air traffic control centre;
ATCO - air traffic control officer..
ATIS - automatic terminal inＦＯＲＭation service, a continuous recorded broadcast of routine non-control airport inＦＯＲＭation, usually at large airports.
ATPL - Air Transport Pilot\transport aircraft exceeding 20,000 kg all-up weight.
ATO - assisted take-off e.g. J(et) or (R)ocket assisted.
ATS - air traffic service. Also ATSU, ATS Unit.
ATSORA - air traffic services outside regulated airspace.
ATC(U) - air traffic control unit.
ATZ - Aerodrome Traffic Zone. An area of protected airspace surrounding an aerodrome bounded by a circle of 2 nm or 2.5 nm radius (depending on runway length) centred on the mid-point of the longest runway. Permission is required for entry into and movement in an ATZ.
AUW - all-up weight, a term for the total loaded weight of an aircraft, made up of empty weight plus useful load; maximum auw is the maximum allowable weight, including fuel and payload, specified in an aircraft\Certificate of Airworthiness. Sometimes referred to (in USA especially) as gross weight and maximum gross weight respectively. Also MTWA, maximum total weight authorised; BOW Basic operating weight, the weight of an aircraft with all equipment, lubricants, fuel and operating crew, but without payload; MLW, maximum landing weight, above which fuel must be burned off or jettisoned before landing or there may be risk of structural
