• A/A
    Air to Air TACAN function
  • A/P
  • ABAS
    Aircraft-Based Augmentation System
    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
    Air Data And Attitude Heading Reference System
  • ADC
    Air data computer
  • ADF
    Automatic direction finder
  • ADI
    Attitude director indicator
    Air Data Inertial Reference System
    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
    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
    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
  • AOC
    Aeronautical Operational Control
  • AOP
    Airport Operating Plan
    Automatic Pressure Altitude Reporting System
    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
    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
    Air Traffic Control Radar Beacon System
    Air traffic control signalling system
  • ATIS
    Automated Terminal Information Service
    Airborne Traffic Situational Awareness
  • ATSU
    Air Traffic Services Unit
  • ATT
  • Avionics
    Aviation electronics
  • AWOS
    Automated Weather Observation System
    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
    Communication, navigation, surveillance/air traffic Management
  • COMM or COM
    Communications receiver
  • COTS
    Commercial off-the-shelf
    Controller-pilot data link communications
  • CPS
    Cycles per second
  • CRT
    Cathode ray tube
  • CTAF
    Common traffic advisory frequency
    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
    Enhanced ground proximity warning system
  • EGT
    Exhaust gas temperature
  • EHS
    Enhanced surveillance
  • EHSI
    Electronic horizontal situation indicator
    Engine indication crew alerting system
  • ELT
    Emergency locator transmitter
  • ENC
    Electronic noise canceling
  • ENG
  • ENR
    Electronic noise reduction
  • EPR
    Engine pressure ratio
  • ETOP(S)
    Extended-range twin-engine operation(s)
  • FAA
    Federal Aviation Administration
    Full authority digital engine control
  • FAF
    Final approach fix
  • FANS
    Future Air Navigation System
  • FAT
    Free air temperature
  • FBW
  • 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
  • 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
  • GLNS
    GPS Landing and Navigation System
  • GLNU
    GPS landing and navigation unit
    Global Navigation Satellite System
  • GLS
    GBAS Landing System
  • GLU
    GPS landing unit
  • GMT
    Greenwich Mean Time
  • GND
  • 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 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
  • IAP
    Instrument approach procedure
  • IAS
    Indicated airspeed
  • ID
    Identify/Identification or identifier
  • IDS
    Information display system or integrated display system
  • IFE
    In-flight entertainment
  • IFF
    Identification Friend or Foe
    Integrated Flight Instrument and Control System
  • IFR
    Instrument Flight Rules
  • ILS
    Instrument landing system
  • IMC
    Instrument meteorological conditions
  • IND
  • 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
    Joint Tactical Information Distribution System
  • KTAS
    Knots true airspeed
  • LAAS
    Local Area Augmentation System
    Local Area Differential GPS
  • LCD
    Liquid crystal display
    Local area differential global positioning satellite
  • LED
    Light-emitting diode
  • LMM
    Locator middle marker
  • LOC
  • LOM
    Locator outer marker
  • LOPA
    Location of Passenger Accommodations
    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
  • 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
  • MIDS
    Multifunctional information distribution system
    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
  • MSP
    Modes S-Specific Protocol
  • MSSS
    Mode S-Specific Services
  • MTBF
    Mean time between failures
    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
    Navigation and communications equipment or receiver
    NAVigation Satellite Timing And Ranging (The formal name for the space-borne or satellite navigation system)
    National Center for Aircraft Technician Training
  • ND
    Navigation display
  • NDB
    Non-directional radio beacon
  • NFF
    No fault found
  • NM or NMI
    Nautical mile
    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
    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
  • P-RNAV
    precision area navigation
  • PRA
    Pre-recorded announcement
  • PSR
    Primary surveillance radar
  • PSU
    Passenger service unit
  • PTT
  • 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
  • RDMI
    Radio distance magnetic indicator
  • RDP
    Radar data processing system
  • RDR
  • REF
  • REIL
    Runway end identifier lights
  • REL
  • RF
    Radio frequency
  • RFI
    Radio frequency interference
  • RHSM
    Reduced horizontal separation minimal
  • RLG
    Ring laser gyroscope
  • RLY
  • RMI
    Radio magnetic indicator
  • R-NAV
    Area navigation
  • RNG
  • 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
  • RVR
    Runway visual range
  • RVSM
    Reduced vertical separation minimum
  • RX
  • SAR
    Search and Rescue, Smart ACMS Recorder
  • SAT
    Static air temperature
    Satellite communication
    Satellite navigation
  • SD
    Secure digital
  • SDF
    Simplified directional facility
    Selective calling
  • SID
    Standard instrument departure
  • SIU
    Satellite interface unit
  • SMS
    Short Messaging Service
  • SNR
    Signal-to-noise ratio
  • SPKR
  • SQ or SQL
  • SRS
    Speed Reference System
    Solid-state cockpit voice/data recorder
    Solid-state cockpit voice recorder
    Solid-state flight data recorder
  • SSR
    Secondary surveillance radar
  • STAR
    Standard terminal arrival route
    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)
    Tactical air navigation system
  • Tach
  • 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
  • TCU
    TACAN control unit
  • TDOP
    Time dilution of precision
  • TDR
    Transponder (in some cases)
    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
    Terminal radar approach control
    Transmit, Transmission, or Transition
  • TRK
  • 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
  • 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
  • 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
    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 with Distance measuring equipment
  • VOR/MB
    VOR marker beacon
    VOR and TACAN combination
  • VOX
    Voice transmission
  • VPA
    Vertical Path Approach
    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
    Wind direction
  • WMA
    WXR waveguide adapter
  • WMI
    WXR indicator mount
  • WMS
    Wide-area master station
  • WMSC
    Weather message switching center
    Weather message switching center replacement
  • WPT
  • WRT
    WXR receiver transmitter
  • WS
    Wind shear
  • WX
  • WXR
    Weather radar system
  • WYPT
  • XCVR
  • XFR
  • XMIT
  • XMSN
  • XMTR
  • XPDR
  • XTK
  • YD
    Yaw damper
  • Y