A/A
Air to Air TACAN function
A/P
Autopilot
ABAS
Aircraft-Based Augmentation System
ACARS
Aircraft Communications Addressing and Reporting System
ACAS
Airborne collision avoidance system
ACC
Area Control Centre
ACE
Actuator Control Electronics
ACMS
Aircraft Condition Monitoring System
ACP
Audio Control Panel
ACS
Audio Control System
ADAHRS
Air Data And Attitude Heading Reference System
ADC
Air data computer
ADF
Automatic direction finder
ADI
Attitude director indicator
ADIRS
Air Data Inertial Reference System
ADIRU
Air data inertial reference unit
ADM
Air data module
ADS
Either; Automatic Dependent Surveillance or air data system
ADS-A
Automatic Dependent Surveillance-Address
ADS-B
Automatic dependent surveillance - broadcast
ADS-C
Automatic Dependent Surveillance-Contract
AESA
Active electronically scanned array
AFCS
Automatic flight control system
AFD
Autopilot flight director
AFDC
Autopilot flight director computer
AFDS
Autopilot flight director system
AFD
Avionics Full-Duplex Switched Ethernet
AFIS
Either; Automatic flight information service or airborne flight information system
AGACS
Automatic ground-air communications system, is also known as ATCSS or data link
AGC
Automatic gain control
AGDL
Air-Ground Data Link
AHC
Attitude Heading Control
AHRS
Attitude and Heading Reference Systems
AHRU
Attitude and Heading Reference Unit
AIDS
Aircraft Integrated Data System
AIXM
Aeronautical Information eXchange Model
ALC
Automatic Level Control
ALT
Either; altimeter or altitude
ALT Hold
Altitude Hold Mode
ALTS
Altitude Select
AMLCD
Active-matrix liquid crystal display
AMS
Air Management System
ANC
Active Noise Cancellation
ANN
Annunciator - caution warning system normally containing visual and audio alerts to the pilot
ANR
Active Noise Reduction
ANT
Antenna
AOC
Aeronautical Operational Control
AOP
Airport Operating Plan
APARS
Automatic Pressure Altitude Reporting System
APIRS
Attitude and Positioning Inertial Reference System
APOA
Airport of Arrival
APC
Auto Pilot Computer
APOD
Airport of Departure
APM
Aircraft Personality Module
APS
Auto Pilot System
APU
Auxiliary Power Unit
ARINC
Aeronautical Radio, Incorporated
ASD
Aircraft situation display
ASDL
Aeronautical satellite data link
ASR
Airport surveillance radar
ASU
Avionics switching unit
AT
Auto Throttle
ATC
Air traffic control
ATCT
Airport Traffic Control Tower
ATCRBS
Air Traffic Control Radar Beacon System
ATCSS
Air traffic control signalling system
ATIS
Automated Terminal Information Service
ATSAW
Airborne Traffic Situational Awareness
ATSU
Air Traffic Services Unit
ATT
Attitude
Avionics
Aviation electronics
AWOS
Automated Weather Observation System
AWACS
Advanced Warning And Control Systems
ALNA
AirLine Network Architecture
B RNAV
Basic area navigation
BARO
Barometric indication, setting or pressure
BITE
Built-In Test Equipment
BCRS
Back course
BDI
Bearing distance indicator
BGAN
Broadcast Global Area Network
BER
Beyond Economic Repair
CAI
Caution annunciator indicator
CAS
Calibrated airspeed
CAT I
Operational performance Category 1
CAT II
Operational performance Category II
CAT IIIa
Operational performance Category IIIa
CAT IIIb
Operational performance Category IIIb
CAT IIIc
Operational performance Category IIIc
CDA
Continuous descent approach
CDI
Course deviation indicator
CDTI
Cockpit display of traffic information
CFIT
Controlled flight into terrain
CHT
Cylinder Head Temperature
CNS
Communication, navigation, surveillance
CNS/ATM
Communication, navigation, surveillance/air traffic Management
CODEC
Coder/decoder
COMM or COM
Communications receiver
COTS
Commercial off-the-shelf
CPDLC
Controller-pilot data link communications
CPS
Cycles per second
CRT
Cathode ray tube
CTAF
Common traffic advisory frequency
CV/DFDR
Cockpit voice and digital flight data recorder
CVR
Cockpit voice recorder
CWS
Control wheel steering
DA
Decision altitude
DA
Drift angle
DAPs
Downlink of aircraft parameters
DCDU
Data link control and display unit
DCL
Departure Clearance via CPDLC
DCP
Display control panel
DFMC
Dual Frequency Multiple Constellation
DG
Directional gyroscope
DGPS
Differential global positioning system
DH
Decision height
DLR
Data link recorder
DME
Distance measuring equipment
DNC
Direct noise canceling
DP
Departure procedures
DSP
Digital signal processing
DTU
Data transfer unit
DUAT
Direct user access terminal
DVE
Degraded Visual Environment
EADI
Electronic attitude director indicator
ECU
Engine Control Unit (=EEC)
EEC
Electronic Engine Control
EFD
Electronic flight display
EFIS
Electronic flight instrument system
EGI
Embedded GPS Inertial
EGPWS
Enhanced ground proximity warning system
EGT
Exhaust gas temperature
EHS
Enhanced surveillance
EHSI
Electronic horizontal situation indicator
EICAS
Engine indication crew alerting system
ELT
Emergency locator transmitter
ENC
Electronic noise canceling
ENG
Engine
ENR
Electronic noise reduction
EPR
Engine pressure ratio
ETOP(S)
Extended-range twin-engine operation(s)
FAA
Federal Aviation Administration
FADEC
Full authority digital engine control
FAF
Final approach fix
FANS
Future Air Navigation System
FAT
Free air temperature
FBW
Fly-by-wire
FCC
Flight Control Computer
FCS
Flight Control System
FD
Flight Director
FDPS
Flight plan Data Processing System
FDR
Flight Data Recorder
FDRS
Flight data recorder system
FDU
Flux detector unit
FF
Fuel flow
FG
Flight Guidance
FIC
Flight Information Centre
FIS-B
Flight information services - broadcast
FLIR
Forward-looking infra-red
FLTA
Forward-looking terrain avoidance
FMA
Flight Mode Annunciator
FMGS
Flight Management & Guidance System
FMS
Flight management system
FOB
Fuel On-Board
FREQ
Frequency
FSS
Flight service station
FWS
Flight warning system
FYDS
Flight director/ Yaw damper system
GA
Go Around
GAST
GBAS Approach Service Type
GBAS
Ground based augmentation system
GCAS
Ground collision avoidance system
GCU
Generator control unit
GDOP
Geometric dilution of precision
GGS
Global positioning system ground station
GHz
Gigahertz
GLNS
GPS Landing and Navigation System
GLNU
GPS landing and navigation unit
GLONASS
Global Navigation Satellite System
GLS
GBAS Landing System
GLU
GPS landing unit
GMT
Greenwich Mean Time
GND
Ground
GNSS
Global Navigation Satellite System
GO
Go Around
GPS
Global Positioning System
GPWC
Ground proximity warning computer
GPWS
Ground proximity warning system
G/S
Glide Slope
GS
Ground speed
"Hg
Inch of Mercury
HDG
Heading
HDG SEL
Heading select
HDOP
Horizontal dilution of precision
HF
High frequency
HHLD
Heading hold
HIRF
High intensity radiated field
HMD
Helmet-mounted display
HPR
High Pressure Rotor
HSD
High-speed data
HSI
Horizontal situation indicator
HSL
Heading select
HUMS
Health and usage monitoring systems
HUD
Head-up display
Hz
Hertz
IAP
Instrument approach procedure
IAS
Indicated airspeed
ID
Identify/Identification or identifier
IDENT
Identify/identifier
IDS
Information display system or integrated display system
IFE
In-flight entertainment
IFF
Identification Friend or Foe
IFICS
Integrated Flight Instrument and Control System
IFR
Instrument Flight Rules
ILS
Instrument landing system
IMC
Instrument meteorological conditions
IND
Indicator
InHg
Inch of Mercury
INS
Inertial Navigation System
IRS
Inertial Reference System
ISA
International Standard Atmosphere
ISP
Integrated switching panel
ISIS
Integrated standby instrument system
ITT
Interstage turbine temperature
IVSI
Instantaneous vertical speed indicator
JTIDS
Joint Tactical Information Distribution System
KTAS
Knots true airspeed
LAAS
Local Area Augmentation System
LADGPS
Local Area Differential GPS
LCD
Liquid crystal display
LDGPS
Local area differential global positioning satellite
LED
Light-emitting diode
LMM
Locator middle marker
LOC
Localizer
LOM
Locator outer marker
LOPA
Location of Passenger Accommodations
LORAN
Long-range navigation
LPR
Low Pressure Rotor
LPV
Localizer performance with vertical guidance
LRU
Line-replaceable unit
LTE
Loss of Tail Rotor Effectiveness Helicopters
LVP
Low visibility procedures, a designated state of operations at aerodromes where instrument approaches and low visibility takeoff procedures are using during inclement weather
LX
Lightning
MAP
Manifold absolute pressure or missed approach point
MAPS
Minimum Aviation Performance Standards
MB
Marker beacon
MCBF
Mean cycles between failures
MCDU
Multi-purpose/Multi-function Control and Display Unit
MDA
Minimum decent altitude
MEL
Minimum equipment list
MCP
Mode control panel
MF
Medium frequency
MFD
Multi-function display
MFDS
Multi-function display system
MIC
Microphone
MIDS
Multifunctional information distribution system
MILSPEC
Military specification
MKP
Multi-function Keypad
MKR
Marker beacon
MLS
Microwave landing system
MM
Middle marker
MMD
Moving map display
MNPS
Minimum navigation performance specifications
MOA
Military operations area
Mode A
Transponder pulse-code reporting
Mode C
Transponder code and altitude reporting
Mode S
Transponder code, altitude, and TCAS reporting
MOPS
Minimum Operational Performance Standard
MOSArt
Modular Open System Architecture
MSA
Minimum safe altitude
MSG
Message
MSP
Modes S-Specific Protocol
MSSS
Mode S-Specific Services
MTBF
Mean time between failures
MTBUR
Mean time between unscheduled removals
MTTF
Mean time to failure
MVA
Minimum vectoring altitude
MVFR
Marginal visual flight rules
N1
Low Pressure rotor (spool) speed (see Jet engine)
N2
High Pressure rotor (spool) speed (see Jet engine)
NAS
National Airspace System
NAV
Navigation receiver
Navaid
Navigational aid
NAVCOMM
Navigation and communications equipment or receiver
NAVSTAR-GPS
NAVigation Satellite Timing And Ranging (The formal name for the space-borne or satellite navigation system)
NCATT
National Center for Aircraft Technician Training
ND
Navigation display
NDB
Non-directional radio beacon
NFF
No fault found
NM or NMI
Nautical mile
NORDO
No radio
NoTAM
Notice to Airmen
NPA
Non-precision approach
NVD
Night vision device
NVG
Night vision goggles
OAT
Outside air temperature
OBS
Omnibearing selector
OCC
Operations control center
OM
Outer marker
OWE/OEW
Operating Weight Empty/Operating empty weight
PA
Public address system
PAEW
Personnel and equipment working
PAL
Pilot Activated Lighting
PAPI
Precision approach path indicator
PAR
Precision approach radar
PCL
Pilot Controlled Lighting
P-Code
GPS precision code
PD
Profile descent
PDC
Pre-Departure Clearance
PDOP
Position dilution of precision
PESA
Passive electronically scanned array
PFD
Primary flight display or primary flight director
PMG
Permanent magnet generator
PND
Primary navigation display
PNR
Passive noise reduction
POF
Phase of flight
POS
Position
P-RNAV
precision area navigation
PRA
Pre-recorded announcement
PSR
Primary surveillance radar
PSU
Passenger service unit
PTT
Push-to-talk
QAR
Quick Access Recorder
QNH
Barometric pressure adjusted to sea level
QRH
Quick Reference Handbook
RA
Resolution advisory (TCAS)
Rad Alt
Radio Altitude
RAI
Radio altimeter indicator
RAIM
Receiver-autonomous integrity monitoring, also remote autonomous integrity monitoring
RALT
Radar or radio altimeter
RAT
Ram air turbine
RCR
Reverse current relay
RCVR
Receiver
RDMI
Radio distance magnetic indicator
RDP
Radar data processing system
RDR
Radar
REF
Reference
REIL
Runway end identifier lights
REL
Relative
RF
Radio frequency
RFI
Radio frequency interference
RHSM
Reduced horizontal separation minimal
RLG
Ring laser gyroscope
RLY
Relay
RMI
Radio magnetic indicator
R-NAV
Area navigation
RNG
Range
RNP
Required navigation performance
ROC
Rate of climb
ROD
Rate of descent
RPA
Remotely piloted aircraft (Unmanned aerial vehicle)
RPM
Revolutions per minute
RSP
Reversion switch panel
RTE
Route
RVR
Runway visual range
RVSM
Reduced vertical separation minimum
RX
Receiver
SAR
Search and Rescue, Smart ACMS Recorder
SAT
Static air temperature
SATCOM
Satellite communication
SATNAV
Satellite navigation
SD
Secure digital
SDF
Simplified directional facility
SELCAL
Selective calling
SID
Standard instrument departure
SIU
Satellite interface unit
SMS
Short Messaging Service
SNR
Signal-to-noise ratio
SPKR
Speaker
SQ or SQL
Squelch
SRS
Speed Reference System
SSCV/DR
Solid-state cockpit voice/data recorder
SSCVR
Solid-state cockpit voice recorder
SSFDR
Solid-state flight data recorder
SSR
Secondary surveillance radar
STAR
Standard terminal arrival route
STARS
Standard Terminal Automation Replacement System
STC
Supplemental Type Certificate
STCA
Short-Term Conflict Alert
STP
Standard temperature and pressure
SUA
Special use airspace
TA
Traffic advisory (see TCAS)
TACAN
Tactical air navigation system
Tach
Tachometer
TAD
Terrain awareness display
TAF
Terminal area forecast
TAS
True airspeed
TAT
True air temperature, or total air temperature
TAWS
Terrain awareness and warning system
TBO
Time before overhaul, or time between overhaul
TCA
Throttle control assembly, or terminal control area
TCAS
Traffic collision avoidance system
TCF
Terrain clearance floor
TCN
TACAN
TCU
TACAN control unit
TDOP
Time dilution of precision
TDR
Transponder (in some cases)
TERPS
Terminal instrument procedures, or terminal en route procedures
TFR
Temporary flight restrictions
TFT
Thin-film transistor
TGT
Turbine gas temperature, or target
THDG
True heading
TIS
Traffic information service
TK
Track angle
TKE
Track-angle error
TLA
Thrust Lever Angle
TLA
Three-letter acronym
TOD
Top of Descent point
TOGA or TO/GA
Takeoff/Go-around switch, Takeoff/go-around thrust
TOT
Turbine outlet temperature
TR or T/R
Transmitter receiver or transceiver
T/R
Thrust Reverser or Tail Rotor
TRACON
Terminal radar approach control
TRANS
Transmit, Transmission, or Transition
TRK
Track
TRP
Mode S transponder
TTL
Tuned to Localizer
TTR
TCAS II transmitter/receiver
TTS
Time to station
TVE
Total vertical error
TWDL
Two-way data link, or terminal weather data link
TWDR
Terminal Doppler Weather Radar
TWIP
Terminal weather information for pilots
TWR
Terminal weather radar
TX
Transmit
UART
Universal asynchronous receiver transmitter
UAV
Unmanned aerial vehicle
UHF
Ultra-high frequency
ULB
Underwater locator beacon
USB
Universal Serial Bus
UTC
Universal Time Coordinate
V
Volts or voltage
V/L
VOR/Localizer
V/NAV
Vertical navigation
V/R
Voltage regulator
V/REF
Reference velocity
V/S
Vertical speed
V/TRK
Vertical track
VASI
Visual approach slope indicator
VASIS
Visual approach slope indicator (system)
VDF
VHF Direction Finding
VDL
VHF Data Link
VDR
VHF digital radio
VFO
Variable frequency oscillator
VFR
Visual flight rules
VG/DG
Vertical gyroscope/directional gyroscope
VGA
Video Graphics Array
VHF
Very high frequency
VMC
Visual meteorological conditions or minimum control speed with critical engine out
VNE
Never exceed speed
VNO
Maximum structural cruising speed
VNR
VHF navigation receiver
VOR
VHF omnidirectional range and ranging
VOR/DME
VOR with Distance measuring equipment
VOR/MB
VOR marker beacon
VORTAC
VOR and TACAN combination
VOX
Voice transmission
VPA
Vertical Path Approach
VPATH
Vertical path
VRP
Visual Point of Reference
VSI
Vertical speed indicator
VSM
Vertical separation limit
VSO
Stall speed in landing configuration
VSWR
Voltage-standing wave ratio
VX
Speed for best angle of climb
VY
Speed for best rate of climb
WAAS
Wide Area Augmentation System
WD
Wind direction
WINDR
Wind direction
WMA
WXR waveguide adapter
WMI
WXR indicator mount
WMS
Wide-area master station
WMSC
Weather message switching center
WMSCR
Weather message switching center replacement
WPT
Waypoint
WRT
WXR receiver transmitter
WS
Wind shear
WX
Weather
WXR
Weather radar system
WYPT
Waypoint
XCVR
Transceiver
XFR
Transfer
XMIT
Transmit
XMSN
Transmission
XMTR
Transmitter
XPDR
Transponder
XTK
Crosstrack
YD
Yaw damper
Y
YAW