| A | Amber |
| A/A | Air − to − air |
| AAL | Above aerodrome level |
| ABM | Abeam |
| ABN | Aerodrome beacon |
| ABT | About |
| ABV | Above |
| AC | Altocumulus |
| ACAS | Airborne Collision Avoidance System |
| ACC | Area control centre or area control |
| ACCID | Notification of an aircraft accident |
| ACFT | Aircraft |
| ACK | Acknowledge |
| ACL | Altimeter check location |
| ACN | Aircraft classification number |
| ACP | Acceptance (message type designator) |
| ACT | Active or activated or activity |
| AD | Aerodrome |
| ADA | Advisory area |
| ADC | Aerodrome chart |
| ADDN | Addition or additional |
| ADF | Automatic direction−finding equipment |
| ADIZ | Air defence identification zone (to be pronounced “AY − DIZ”) |
| ADJ | Adjacent |
| ADR | Advisory route |
| ADS | Automatic dependent surveillance |
| ADSU | Automatic dependent surveillance unit |
| ADVS | Advisory service |
| AES | Aircraft earth station |
| AFIL | Flight plan filed in the air |
| AFI | Africa − Indian Ocean |
| AFIS | Aerodrome flight information service |
| AFM | Yes or affirm or affirmative or that is correct |
| AFS | Aeronautical fixed service |
| AFTN | Aeronautical fixed telecommunication network |
| A/G | Air−to−ground |
| AGA | Aerodromes, air routes and ground aids |
| AGL | Above ground level |
| AGMC | Aerodrome ground movement chart |
| AIC | Aeronautical information circular |
| AIP | Aeronautical information publication |
| AIRAC | Aeronautical information regulation and control |
| AIREP | Air−report |
| AIRMET | Information concerning en−route weather phenomena which may affect the safety of low−level aircraft operations |
| AIS | Aeronautical information services |
| ALA | Alighting area |
| ALERFA | Alert phase |
| ALR | Alerting (message type designator) |
| ALRS | Alerting service |
| ALS | Approach lighting system |
| ALT | Altitude |
| ALTN | Alternate or alternating (light alternates in colour) |
| ALTN | Alternate (aerodrome) |
| AMA | Area minimum altitude |
| AMC | Airspace management cell |
| AMD | Amend or amended (used to indicate amended meteorological message |
| AMDT | Amendment (AIP amendment) |
| AMS | Aeronautical mobile service |
| AMSL | Above mean sea level |
| ANC | Aeronautical chart − 1:500 000 (followed by name/title) |
| AO | Aircraft operator |
| AOC | Aerodrome obstacle chart (folloved by name/title) |
| AP | Airport |
| APCH | Approach |
| APDC | Aircraft parking/docking chart (folloved by name/title) |
| APN | Apron |
| APP | Approach control office or approach control or approach control service |
| APR | April |
| APRX | Approximate or approximately |
| APV | Approve or approved or approval |
| APT | Receiver for satellite cloud pictures |
| ARFOR | Area forecast (in aeronautical meteorological code) |
| ARO | Air traffic services reporting office |
| ARP | Aerodrome reference point |
| ARP | Air−report (message type designator) |
| ARR | Arrival (message type designator) |
| ARR | Arrive or Arrival |
| ARS | Special air−report (message type designator) |
| AS | Altostratus |
| ASC | Ascend to or ascending to |
| ASDA | Accelerate−stop distance available |
| ASM | Airspace management |
| ASPH | Asphalt |
| AT... | At (followed by time at which weather change forecast to occur) |
| ATA | Actual time of arrival |
| ATC | Air traffic control (in general) |
| ATD | Actual time of departure |
| ATFM | Air traffic flow management |
| ATIS | Automatic terminal information service |
| ATM | Air traffic management |
| ATN | Aeronautical telecommunication network |
| ATS | Air traffic services |
| ATTN | Attention |
| ATZ | Aerodrome traffic zone |
| AUG | August |
| AUP | Airspace use plan |
| AUTH | Authorized or authorization |
| AUW | All up weight |
| AUX | Auxiliary |
| AVASIS | Abbreviated visual approach slope indicator system |
| AVBL | Available or availability |
| AVG | Average |
| AVGAS | Aviation gasoline |
| AWY | Airway |
| AZM | Azimuth |
© 2012-21 Kristina Novotna