| A (+ number) | Amber or Alpha (airway designator); Alert Area (number); Asphalt |
| A/A | Air-to-Air |
| AAF | Army Air Field |
| AAI | Angle of Approach Indicator |
| AAL | Above Aerodrome Level |
| AAS | Airport Advisory Service |
| AAU | Authorised Approach UNICOM |
| AB | Air Base |
| ABM | Abeam |
| ABN | Aerodrome Beacon |
| ABT | About |
| ABV | Above |
| AC | Air Carrier |
| ACA | Arctic Control Area |
| ACA | Approach Control Area |
| ACARS | Airborne Communications Addressing and Reporting System |
| ACAS | Airborne Collision Avoidance System |
| ACC | Area Control Centre or Area Control |
| ACC | Accumulated |
| ACFT | Aircraft |
| ACCID | Notification of an aircraft accident |
| ACN | Aircraft Classification Number |
| ACP | Airlift Command Post |
| ACPT | Accept; Accepted |
| ACT | Active/activated |
| ACU | Air Conditioning Unit |
| AD | Aerodrome |
| ADA | Advisory Area |
| ADDN | Addition; Additional |
| ADF | Automatic Direction Finding Equipment |
| ADIZ | Air Defence Identification Zone |
| ADJ | Adjacent |
| ADR | Advisory Route |
| ADV | Advisory Area |
| ADZ | Advise |
| AEIS | Aeronautical En route Information Service |
| AER | Approach End Runway |
| AERADIO | Air Radio |
| AERO | Aerodrome |
| AES | Aerodrome Emergency Services |
| AF Aux | Air Force Auxiliary Field |
| AFB | Air Force Base (US) |
| AFDS | Autopilot Flight Director System |
| AFI | Africa/Indian Ocean OCAO Region) |
| AFIS | Aerodrome Flight Information Service |
| AFL | Above Field Level |
| AFN | American Forces Network |
| AFRC | Armed Forces Reserve Centre |
| AFRN | Alaskan Forces Radio Network |
| AFRS | Armed Forces Radio Stations |
| AFS | Aeronautical Fixed Service |
| AFS | Air Force Station |
| AFSS | Automated Flight Service Station |
| AFT | After .... (time or place) |
| AFTN | Aeronautical Fixed Telecommunication Network |
| A/G | Air - to - Ground |
| A-G | Arresting Gear |
| AGA | Aerodrome and Ground Aids |
| AGL | Above Ground Level |
| AGN | Again |
| AGNIS | Azimuth Guidance Nose - in - Stand |
| AH | Alert Height |
| AHP | Army Heliport |
| AIAA | Area of Intensive Aerial Activity |
| AIC | Aeronautical Information Circular |
| AIP | Aeronautical Information Publication |
| AIRAC | Aeronautical Information Regulation and Control |
| AIREP | Air - Report |
| AIS | Aeronautical Information Service |
| ALA | Authorised Landing Area |
| ALCE | Airlift Control Element |
| ALERFA | Alert Phase |
| ALF | Auxiliary Landing Field |
| ALS | Approach Light System |
| ALSF-1 | Approach Light System with Sequenced Flashing Lights |
| ALSF-2 | Approach Light System with Sequenced Flashing |
| | Lights and Red Side Row Lights the last 1000'. |
| ALT | Altitude |
| ALTN | Alternate/Alternating |
| AMA | Area Minimum Altitude |
| AMD | Amend/amended |
| AMS | Aeronautical Mobile Service |
| AMSL | Above Mean Sea Level |
| ANGB | Air National Guard Base |
| AO | Non Modulated Transmission |
| AOC | Aerodrome Obstruction Chart |
| AOE | Airport/Aerodrome of Entry |
| AOM | Aeroplane Operation Manual |
| AOR | Area of Responsibility |
| AP | Airport |
| APAPI | Abbreviated Precision Approach Path Indicator |
| APC | Area Positive Control |
| APCH | Approach |
| APP | Approach Control or Approach Control Office |
| APRX | Approximately |
| APR | April |
| APT | Airport |
| APU | Auxiliary Power Unit |
| ARB | Air Reserve Base |
| ARFF | Airport Rescue & Fire Fighting |
| ARINC | Aeronautical Radio Inc. |
| ARO | Air Traffic Services Reporting Office |
| ARO | Aerodrome Reporting Officer |
| ARP | Aerodrome Reference Point |
| ARR | Arrival |
| ARR | Air Route Surveillance Radar |
| ARS | Air Rescue Service (US) |
| ARTC | Air Route Traffic Control (US) |
| ARTCC | Air Route Traffic Control Centre (US) |
| ASAP | As soon as possible |
| ASC | Ascent: Ascending to |
| AS CL | As cleared |
| ASDA | Accelerate Stop Distance Available |
| ASDE | Airport Surface Detection Equipment |
| ASL | Above Sea Level |
| ASMI | Aerodrome Surface Movement Indicator (taxi radar |
| ASOS | Automated Surface Observation System |
| ASPH | Asphalt |
| ASR | Aerodrome Surveillance Radar |
| ASU | Air Starter Unit |
| ATA | Actual Time of Arrival |
| ATC | Air Traffic Control |
| ATCAA | Air Traffic Control Assigned Airspace |
| ATCC | Air Traffic Control Centre |
| ATCRBS | Air Traffic Control Radar Beacon System |
| ATCT | Air Traffic Control Tower |
| ATD | Actual Time Of Departure |
| ATF | Aerodrome Traffic Frequency |
| ATFM | Air Traffic Flow Management |
| ATIS | Automatic Terminal Information Service |
| ATO | Actual Time Over |
| ATPL | Airline Transport Pilot Licence |
| ATS | Air Traffic Service |
| ATTN | Attention |
| AT-VASI | Abbreviated Tee Visual Approach Slope Indicator |
| ATZ | Aerodrome Traffic Zone |
| AUG | August |
| AUTH | Authorised |
| AUW | All Up Weight |
| AUX | Auxiliary |
| AVASIS | Abbreviated Visual Approach Slope System |
| AVBL | Available |
| AVG | Average |
| AVGAS | Aviation Gasoline |
| AWIB | Aerodrome Weather Information Broadcast |
| AWOS | Automated Weather Observing System |
| AWY | Airway |
| AZM | Azimuth |
