AIR—Aircraft Certification Service

AIRMET—Airman’s Meteorological Information

ALT ACQ—Altitude Acquire

ALT Hold—Altitude Hold

ANP—Actual Navigation Performance

AOC—Aircraft Operational Communications

APT WP—Airport Waypoint

APV—Approach with Vertical Guidance

ARINC—Aeronautical Radio Incorporated

A-RNAV—Advanced Area Navigation

ARTCC—Air Route Traffic Control Center

ARTS—Automated Radar Terminal System

ASDA—Accelerate-Stop Distance Available

ASDE-X—Airport Surface Detection Equipment-Model X

A-SMGCS—Advanced Surface Movement Guidance and Control System

ASOS—Automated Surface Observing System

ASR—Airport Surveillance Radar

ASRS—Aviation Safety Reporting System

ATA—Air Transport Association

ATC—Air Traffic Control