| Name | Detail |
| A | ampere(s) |
| A | autotuned navaid |
| A&P | airframe and power plant |
| A/B | autobrake |
| A/C | aircraft |
| A/D | analog-to-digital |
| A/G | air/ground; air to ground |
| A/L | airline |
| A/L | autoland |
| A/N | alphanumeric |
| A/P | autopilot |
| A/T | autothrottle |
| AAC | aeronautical administration communications |
| AAC | airline administrative communications |
| AAF | airway facilities service |
| AAI | Airline Avionics Institute |
| AAIB | Air Accident Investigation Branch (U.K. equivalent of NTSB) |
| AAIPT | Aging Aircraft Enterprise Team |
| AAIU | air accident investigation unit |
| AAL | above aerodome level |
| AALC | autonomous approach landing capability |
| AAMP | advanced architecture microprocessor |
| AAR | Automated Aerial Refueling |
| AAS | advanced automation system (FAA) |
| AATD | Aviation Applied Technology Directorate (U.S.Army) |
| AATT | advanced air transportation technology |
| ABC | automatic brightness control |
| A-BPSK | aviation binary phase shift keying |
| AC | advisory circular |
| AC | alternating current |
| AC2 | Dolby surround |
| ACAA | Air Carrier Association of America |
| ACAC | air-cooled air cooler |
| ACAMS | aircraft condition analysis management system |
| ACARS | aircraft communications addressing and reporting system |
| ACAS | airborne collision avoidance system |
| ACC | active clearance control |
| ACC | airspace control center |
| ACC | area control center |
| ACD | automatic conflict detection |
| ACDO | Air Carrier District Office |
| ACE | actuator control electronics |
| ACE | advanced certification equipment |
| ACF | area control facility |
| ACG | Assessment Compliance Group |
| ACIPS | airfoil cowl ice protection system |
| ACK | acknowledgment |
| ACMF | airplane condition monitoring function |
| ACMP | alternating current motor pump |
| ACMS | aircraft condition monitoring system |