ACAS /TCAS
Airborne or Traffic Collision Avoidance System. These will have a further descriptor of 'RA' - Resolution Advisory or 'TA' - Traffic Advisory
ADS-B/C
Automatic Dependent Surveillance - Broadcast / Contract
AGL
Above Ground Level
AHRS
Attitude & Heading Reference System
AMSL
Above Mean Sea Level
APU
Auxiliary Power Unit
ATC
Air Traffic Control
ATIS
Automatic Terminal Information Service
CPDLC
Controller Pilot Data Link Communications
CTA
Control Area
CTAF
Common Traffic Advisory Frequency
CTR
Control Zone
DME
Distance Measuring Equipment
ECAM…