Glossary of Avionics Terms & Acronyms
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3D, 4D  Three or four dimension 
4096 Code  The octal base, four-digit code used between framing 
pulses of a reply to identify the aircraft or for general 
use and emergency codes (XPD). 
A300  Airbus Industrie Model 300 Aircraft 
A310  Airbus Industrie Model 310 Aircraft 
A319  Airbus Industrie Model 319 Aircraft 
A320  Airbus Industrie Model 320 Aircraft 
A330  Airbus Industrie Model 330 Aircraft 
A340  Airbus Industrie Model 340 Aircraft 
AAAE  American Association of Airport Executives 
AAC  Aeronautical Administrative Communications 
AAL  (1) American Airlines 
(2) Above Aerodome Level 
AAMP  Advanced Architecture Micro-Processor 
AAS  Advanced Automation System 
AAT  FAA Air Traffic Control Service 
AATT  Advanced Air Transportation Technology (NASA 
Program) 
A/B  Autobrake 
A-BPSK  Aeronautical Binary Phase Shift Keying 
ABRV  Abbreviation 
ABS  Absolute 
Absolute  The altitude of the aircraft above the terrain. 
Altitude  Also known as AGL (above ground level). 
AC  (1) Advisory Circular 
(2) Alternating Current 
A/C  Aircraft 
ACAC  Air-Cooled Air Cooler 

ACARS  Airborne Communications Addressing and Reporting 
System 
ACAS  Airborne Collision Avoidance System 
ACC  Active Clearance Control 
ACCC  Area Control Computer Complex 
Acclrm  Accelerometer 
ACE  (1) The control character meaning technical 
acknowledge 
(2) Actuator Control Electronics 
(3) Advanced Certification Equipment 
ACI  Airports Council International 
ACI-NA  Airports Council International-North America 
ACIPS  Airfoil and Cowl Ice Protection System 
ACK  The control character meaning technical acknowledg-
ment of an uplink,used in an ACARS system 
ACM  Air Cycle Machine 
ACMF  Airplane Condition Monitoring Function 
ACMP  Alternating Current Motor Pump 
ACMS  Aircraft Condition Monitoring System 
ACNSS  Advanced Communication/Navigation/Surveillance 
System 
ACP  Audio Control Panel 
ACR  Avionics Computer Resource 
ACS  Active Control System 
ACU  (1) Apron Control Unit 
(2) Autopilot Control Unit 
(3) Antenna Control Unit 
A/D  Analog-To-Digital