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3D, 4D    three- or four-dimensional
4096 CODE    the octal base, four-digit code used between framing pulses of a reply to identify an aircraft or for general use and emergency codes (XPD)
A    ampere(s)
A    autotuned navaid
AAC    aeronautical administration communications
AAC    airline administrative communications
AAL    above aerodome level
AAMP    advanced architecture microprocessor
AATT    advanced aviation transportation technology
AAS    advanced automation system (FAA)
A/B    autobrake
ABC    automatic brightness control
A-BPSK    aviation binary phase shift keying
AC    advisory circular
AC    alternating current
A/C    aircraft
ACAC    air-cooled air cooler
ACARS    aircraft communications addressing and reporting system
ACAS    airborne collision avoidance system (FAA)
ACC    active clearance control
ACC    area control center
ACD    automatic conflict detection
ACE    actuator control electronics
ACE    advanced certification equipment
ACIPS    airfoil cowl ice protection system
ACF    area control facility
ACK    acknowledgment
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
ACS    active control system
ACS    audio control system
ACT    active
ACTC    airport traffic control towers
ACTD    advanced concept technology demonstration
ACU    apron control unit
ACU    autopilot control unit
ACU    antenna control unit
AD    airworthiness directives (FAA)
A/D    analog-to-digital
ADA    a computer programming language
ADC    air data computer
ADF    automatic direction finding
ADI    attitude direction indicator
ADIRS    air data inertial reference system
ADIRU    air data inertial reference unit
ADL    aeronautical data link
ADLP    aircraft data link processor (Mode S)
ADLP    airborne data link protocol
ADM    air data module
ADMS    airline data management system
ADP    air driven pump
ADR    address
ADR    alternative dispute resolution
ADRAS    airplane data recovery and analysis system
ADS    automatic dependent surveillance
ADS    air data system
ADS-A    automatic dependent surveillance- addressed
ADSA    automatic dependent surveillance- automation
ADS-B    automatic dependent surveillance- broadcast
ADSEL    address selective
ADSP    automatic dependent surveillance panel
ADSSG    ADS Study Group (ICAO)
ADSU    automatic dependent surveillance unit
AECU    audio electronic control unit
AED    ALGOL extended for design
AEEC    Airlines Electronic Engineering Committee (ARINC)
AEP    ARINC engineering practices
AEP    audio entertainment player
AERA    automated en route air traffic control
AES    aircraft earth station (Inmarsat)
AESS    aircraft environment surveillance system
AF    airway facilities
AFC    Aeronautical Frequency Committee (AEEC)
AFC    automatic frequency compensation
AFC    automatic frequency control
AFCAS    automatic flight control augmentation system
AFCS    automatic flight control system
AFD    adaptive flight display
AFD    autopilot flight director
AFDC    autopilot flight director computer
AFDS    autopilot flight director system
AFDX    avionics full-duplex Ethernet switch
AFEPS    ACARS front-end processing system
AFGCS    automatic flight guidance and control system
AFI    authority format identifier
AFIS    airborne flight information system
AFIS    automatic flight information service
AFIS    automated flight inspection system
AFM    aircraft flight manual
AFN    air traffic services facilities notification
AFS    aeronautical fixed service (ICAO)
AFS    automatic flight system
AFSK    audio frequency shift keying
AFSS    automated flight service stations
AFTN    aeronautical fixed telecommunications network
AFTRCC    Aerospace and Flight Test Radio Coordinating Council
AFU    artificial feel unit
A/G    air/ground; air to ground
AGACS    automatic A/G communication system
AGAE    A/G applications engineering
AGATE    Advanced General Aviation Transport Experiments (NASA)
AGC    automatic gain control
AGCOS    A/G communication services
AGCU    auxiliary generator control unit
AGDL    A/G data link
AGIS    A/G intermediate system
AGL    above ground level
AGR    A/G router
AGRM    air/ground router-regional manager
AGS    A/G system
AGSS    ACARS ground system standard (AEEC)
AGTS    A/G test station
AGVS    A/G voice subnetwork
AGW    ARTS gateway
AHC    attitude heading computer
AHRS    attitude heading reference system
AI    alternative interrogator
AI    artificial intelligence
AIC    aeronautical information circular
AIDC    air traffic services interfacility data communications
AIDS    aircraft/airborne integrated data system
AIED    aeronautical industry engineering and development
AIEM    Airlines International Electronic Meeting (AMC)
AIFSS    automated international flight service stations
AIL    aileron
AIMS    airport information management system
AINSC    aeronautical industry service communication
AIO    analog input/output
AIP    aeronautical information publication
AIP    analog input
AIP    Airport Improvement Program (FAA)
AIRAC    aeronautical information regulation and control
AIRCOM    digital air/ground communications service (SITA)
AIRMET    airman’s meteorological information
AIRO    analog input/reference output
AIS    aeronautical information service
AIS    automatic information services (Eurocontrol)
AISG    Applications Interface Subgroup (IATA)
AIV    accumulator isolation valve
AJPS    AFEPS journal processing system
A/L    autoland
ALC    airline link control
ALC    asynchronous link control
ALC    automatic level control
ALPA    Air Line Pilots Association
ALPS    automatic line protection service
ALS    application layer structure
ALT    airborn link terminal
ALT    altitude/alternate
ALD HOLD    altitude hold mode
ALTM    altimeter
ALTN    alternate
ALTS    altitude select
ALU    arithmetic and logic unit
AM    access module
AM    amplitude modulation
AMASS    airport movement area safety system
AMC    Avionics Maintenance Conference
AMCP    aeronautical mobile communications panel
AME    amplitude modulation equivalent
AMI    airline modifiable information
AMLCD    active matrix liquid crystal display
AMP    audio management panel
AMPL    amplifier
AMS    ARINC maintenance service
AMS    apron management service
AMS    avionics management service
AMS    acquisition management system
AMS(R)S    aeronautical mobile satellite (route) service
AMSS    aeronautical mobile satellite service
AMTOSS    aircraft maintenance task oriented support system
AMTS    aeronautical message transfer service
AMU    audio management unit
AMU    ACARS/avionics management unit
AMUX    audio multiplexer
A/N    alphanumeric
ANC    Air Navigation Commission (ICAO)
ANDC    airport and navigation data compiler
ANICS    Alaskan NAS Interfacility Communication
ANLP    ARINC network layer protocol
ANP    actual navigation performance
ANP    air navigation plan/performance
ANS    air navigation system
ANS    ambient noise sensor
ANSI    American National Standards Institute
ANTC    advanced networking test center
AO    acronymic obfuscation
AOA    angle of attack
AOC    airport obstruction chart
AOC    airport operational communications
AOC    aircraft operational control
AOC    airline operational control
AOC    aeronautical operational control
AOC    airline operations center
AOCC    airline operations control center
AODB    airport operational database
AODC    age of data, clock (GPS)
AODE    age of data, ephemeris (GPS)
AOG    aircraft on ground
AOHE    air/oil heat exchanger
AOM    aircraft operating manual
AOP    analog output
AOP    aeronautical OSI profile
AOP    airline operational procedure
AOPA    Aircraft Owners and Pilots Association
AOR    Atlantic Ocean region
AOR-E    Atlantic Ocean region-east
AOR-W    Atlantic Ocean region-west
AP    airport location (ACARS/AFEPS)
A/P    autopilot
APA    autopilot amplifier
APA    Allied Pilots Association
APANPIRG    ASIA/PAC Air Navigation Planning & Implementation Regional Group
APB    auxiliary power breaker
APB    acquisition program baseline
APC    aeronautical passenger communication
APC    aeronautical public correspondence
APC    autopilot computer
APFDS    autopilot flight director system
APMS    automated performance measurement system
API    application programming interface
APN    ARINC packet network
APP    approach control
APPR    approach
APR    actual performance reserve
APRL    ATN profile requirement list
APU    auxiliary power unit
APUC    auxiliary power unit controller
AQF    avionics qualification facility
AQP    advanced qualification program
AQP    avionics qualification procedure/program
A-QPSK    aeronautical quadrature phase shift keying
AQS    advanced quality system
ARAC    Aviation Rulemaking Advisory Committee (FAA)
ARB    arbitrary waveform generator
ARD    advanced requirement definition
ARDEP    analysis of research & development in Eurocontrol programs
ARF    airline risk factor
ARM    area regional manager
ARMC    area regional maintenance center
ARP    address resolution protocol
ARP    air data reference panel
ARRAS    airport remote radio access system
ARS    administrative region selector
ARS    automated radar summary (chart)
ARSR    area/air route surveillance radar
ART    automatic reserve thrust
ARTAS    ATM surveillance tracker & server system (Eurocontrol)
ARTCC    air route traffic control center
ARTS    automated radar terminal system
A/S    airspeed
AS-3    Avionics System Group 3 (SAE)
ASA    aircraft separation assurance
ASA    autoland status annunciator (AFDS)
ASAA    ACARS system access approval (AEEC)
ASAC    Aviation Security Advisory Committee (FAA)
ASAS    aircraft separation assurance system (AEEC)
ASC    aircraft system controller
ASC    aural synthesizer card
ASCII    American standard code for information interchange
ASCPC    air supply and cabin pressure controllers
ASCS    air supply control system
ASCU    anti-skid control unit
ASD    aircraft situation display
ASDAR    aircraft-to-satellite data relay
ASDE    airport surface detection equipment
ASDL    aeronautical satellite data link
ASDR    airport surface detection radar
ASE    altimetry system error
ASECNA    Agency for Security of Aerial Navigation in Africa and Madagascar
ASG    ARINC signal gateway
ASI    avionics system integration
ASIC    application specific integrated circuit
ASL    above sea level
ASM    airspace management
ASM    autothrottle servo motor
A-SMGCS    advanced surface movement guidance and control systems
ASOS    automated surface observation system
ASP    ACARS subnetwork protocol
ASP    altitude set panel
ASP    aeronautical fixed service systems planning (AFS)
ASP    acquisition strategy paper
ASPP    application specific programmable processor
ASR    airport surveillance radar
ASRS    aviation safety reporting system
ASSTC    aerospace simulation and systems test center
ASSV    alternate source selection valve
ASTA    airport surface traffic automation
ASTF    airspace system task force
ASTOR    Airborne Stand-Off Radar (UK)
ASV    alternate servo valve
AT    air transport
AT    at an altitude
A/T    autothrottle
ATA    Air Transport Association of America
ATA    actual time of arrival
ATAS    aviation traffic and application software
ATC    air traffic control
ATCA    Air Traffic Control Association
ATCBI    ATC beacon interrogator
ATCC    area and terminal control center
ATCRBS    ATC radar beacon system
ATCSS    ATC signaling system
ATCT    airport traffic control tower (FAA)
ATDL    air transport data link
ATE    automatic test equipment
ATE    avionics test and evaluation
ATFM    air traffic flow management
ATHR    autothrust system
ATI    airborne tracker illuminator
ATIDS    airport surface target identification system/service
ATIS    airport traffic information system
ATIS    automatic terminal information service
ATL    autothrottle limit
ATLAS    abbreviated test language for avionics systems
ATM    air traffic management
ATM    asynchronous transfer mode
ATMAS    ATM automation system
ATM DSS    ATM decision support service
ATMS    area navigation, test and management services
ATN    aeronautical telecommunication network
ATNE    ATN engineering
ATNP    ATN panel
ATP    acceptance test procedure/plan
ATPAC    Air Traffic Procedures Advisory Committee (FAA)
ATR    acceptance test report
ATR    air transport racking
ATS    air traffic services
ATS    air turbine starter
ATS    autothrottle system
ATSC    air traffic services communication
AT/SC    autothrottle/speed control
ATSGF    air traffic services geographic filter
ATSMP    air traffic services message processor
ATSO    air traffic services organization
ATSP    air traffic services provider
ATSRAC    Aging Transport Systems Rulemaking Advisory Committee (FAA)
ATSU    air traffic services unit
AUX    auxiliary
AVC    aviation VHF car rental availability(messages)
AVH    aviation VHF hotel availability(messages)
AVLAN    avionics local area network
AVLC    aviation VHF link control
AVM    airborne vibration monitor
AVN    avionics
AVOL    aerodrome visibility operational level
AVPAC    aviation VHF packet communications
AVS    aviation VHF seat availability (messages)
AWACS    airborne warning and control system
AWAS    automated weather advisory station
AWG    American wire gauge
AWIN    aviation weather information
AWIPS    advanced weather interactive processing system
AWM    auto warning mixer
AWO    all weather operations
AWOP    AWO panel
AWOS    automated/airport weather observing system
AWR    aviation weather research



BDMIS    business data management and invoicing system
BDS    comm-B designation subfield
BEP    back-end processor
BEPMS    BEP management system
BER    bit error rate
BFE    buyer furnished equipment
BFO    beat frequency oscillator
BGI    bus grant inhibit
BGP    border gateway protocol
BI    burn-in
BiGs    bilingual ground station (ACARS and VDL Mode 2)
Binary    base-2 counting system
BIS    boundary intermediate system
BISMS    BIS management system
BIST    built-in self-test
BiSync    binary synchronous control
BIT    built-in test
Bit    a binary digit
BITE    built-in test equipment
BLK    block/black
BMV    brake metering valve
BNR    binary
BNS    boundary notification system (squitters)
BOC    bottom of climb
BOP/COP    bit-oriented protocol/ character-oriented protocol
BP    bite processor
BPCU    bus power control unit
BPS    bits per second
BPSK    binary phase shift keying
BR    bridge
BRG    bearing
BRI    basic rate interface
BRT    brightness
BSN    backbone subnetwork
BSC    binary synchronous communication
BSCU    brake system control unit
BSP    board support package
BSU    beam steering unit
BSU    bypass switch unit
BTB    bus tie breaker
BTMU    brake temperature monitor unit
BU    backup
BUEC    BU emergency communications
BUFR    binary universal form for communication representation
BWAN    BU wide area network
Byte    a grouping of eight bits



CAA    civil aviation authority
CAAC    Civil Aviation Administration of China
CAB    Civil Aeronautics Board
C&C    command and control (also C2)
C&W    control and warning
CAASD    Center for Advanced Aviation System Development (Mitre Corp.)
CAC    caution advisory computer
C/A code    course acquisition code (GPS)
CACP    cabin area control panel
CAD    computer-aided design
CADAG    Communications, Automation and Data Link Applications Group
CADS    centralized automatic dependent surveillance
CAE    component application engineer
CAGE    commercial avionics GPS engine
CAH    cabin attendant handsets
CAI    caution annunciator indicator
CALSEL    variation of SELCAL system
CAM    computer-aided manufacturing
CARE    cooperative actions on R&D in Eurocontrol
CAS    collision avoidance system
CAS    computed airspeed
CAS    commercially available software
CASE    computer-aided software engineering
CAT    category
CAT    clear air turbulence
CAT    computer aided testing
CAT    categories (I, II, IIIa/b/c) approach
CBA    cost/benefit analysis
CBT    computer-based training
CC    connection confirm
CCB    converter circuit breaker
CCB    configuration control board
CCD    category class diagram
CCD    cursor control device
CCD    charged coupled device
CCB    configuration control board
CCIR    International Radio Consultative Committee
CCITT    Consultative Committee International Telephone and Telegraph
CCP    consolidated control panel
CCS    cabin communication system
CCTV    closed-circuit television
CD    chrominance difference
CD    carrier detect
CDA    coordinating design authority
CDG    configuration database generator
CDI    course deviation indicator
CDM    collaborative decision-making
CDMS    CDM system
CDP    continuous data program
CDR    critical design review
CDS    common display system
CDTI    cockpit display of traffic information
CDU    control display unit
CEPT    Conference Europeene des Postes et Telecommunications
CF    change field
CFDIU    centralized fault display interface unit
CFDS    central fault display system
CFDU    configurable file data unit
CFIT    controlled flight into terrain
CFM    cubic feet per minute
CFM    configuration management
CFMU    central flow management unit
CFS    cabin file server
CG    center of gravity
CHI    computer/human interface
CHIS    center hydraulic isolation system
CI    configuration item
CI    cabin interphone
CID    category interaction diagram
CIDIN    common ICAO data interchange network
CIDS    cabin interphone distribution system
CIE    Commission Internationale de I ‘Eclairage
CIP    capital investment plan
CIP    convergence & implementation program (Eurocontrol)
CIS    common information services
CIS    corporate information system
CLNP    connectionless network protocol
CLNS    connectionless network service
CLTP    connectionless mode transport protocol
CM    context/configuration management
CMC    central maintenance computer
CMCF    CMC function
CMCS    CMC system
CMD    command
CMF    common message format
CMGT    contract management
CMM    capability maturity model
CMM    component maintenance manual
CMM    common mode monitor
CMN    control motion noise
CMOS    complementary metal oxide semiconductor
CMP    configuration management plan
CMS    cabin management system
CMU    communication management unit
CNDB    customized navigation database
CNES    Centre National d’Etudes Spatiales
C/NO    carrier-to-noise density ratio
CNP    com/nav/pulse
CNS    communication, navigation surveillance
CNS/ATM    communications, navigation, surveillance/air traffic management
CODEC    coder/decoder
COM    cockpit operating manual
COM    communications
COMM    communications
COM/MET/OPS    communications/ meteorological/operations
CON    continuous
COMSAT    Communications Satellite Corp.
CONOPS    concept of operations
CONUS    continental United States
COP    character-oriented protocol
COTP    connection-oriented transport protocol
COTR    contracting officer’s technical representative
COTS    commercial-off-the-shelf
CP    central processor
CP    conflict probe
CP    control panel
CPA    closest point of approach
CPA    collision prediction and alerting
CPC    controller-pilot communications
CPC    cabin pressure controller
CPC    cursor position control
CPCI    computer program configuration item
CPCS    cabin pressure control system
CPDLC    controller-pilot data link communications
CPE    circular position error
CPI    continuous process improvement
CPM    core processor module
CPM    critical path method
CPS    cabin pressure sensor
CPS    central processing system
CPU    central processing unit
C/R    command/response
CR    change of request
CR    contrast ratio
CR    connection request
CRC    cyclic redundancy checking/code
CRD    current routing domain
CRDA    cooperative research and development agreement
CRM    crew/cockpit resource management
CRPA    controlled reception pattern antenna
CRISD    computer resources integrated support document
CRM    collision risk model
CRM    crew resource management
CRR    cutover readiness review
CRS    course
CRT    cathode ray tube
CRZ    cruise
CS    common service
CSC    common signaling channel
CSC    cargo system controller
CSC    computer software component
CSCI    computer software configuration item
CSF    command/status frame
CSMA    carrier sense multiple access
CSMA/CD    carrier sense multiple access with collision detection
CSCP    cabin system control panel
CSDB    commercial standard data bus
CSDS    cargo smoke detector system
CSEU    control systems electronics unit
CSMM    crash survivable memory modules
CSMU    cabin system management unit
C/SOIT    communications/surveillance operational implementation team
CSPA    closely spaced parallel approach
CSTAC    Commercial Space Transportation Advisory Committee

CSU    configuration strapping unit

CSU    channel service unit

CSU    computer software unit

CTA    control area
CTA    controlled time of arrival
CTAF    common traffic advisory frequency
CTAI    cowl thermal anti-icing
CTAS    center TRACON automation system
CTC    cabin temperature controller
CTL    control
CTMO    centralized air traffic flow management organization
CTOL    conventional takeoff and landing
CTR    control zone
CTR    center
CTRD    configuration test requirements document
CTRL    control
CTS    clear to send
CTS    conformance test suite
CTU    cabin telecommunications unit
CU    combiner unit (HUD)
CU    channel utilization
CU    control unit
CUG    closed user group
C/UT    code/unit test
CUTE    common use terminal equipment
CV/DFDR    cockpit voice and digital flight data recorder
CVR    cockpit voice recorder
CVRCP    cockpit voice recorder control panel
CW    continuous wave
CW    clockwise
CWI    continuous wave interference
CWP    controller/ed working position
CWS    control wheel steering



D8PSK    differential 8-phase-shift keying
DA    descent advisor
DA    design authority
DA    digital-to-analog
DABS    discrete addressable beacon system
DADC    digital air data computer
DADS    digital air data system
DAP    digital service access product
DAR    data access recorder
DARC    direct access radar channel
DARP    dynamic aircraft route planning
DARPA    Defense Advanced Research Projects Agency
D-ATIS    digital automatic terminal information service
DB    database
dB    decibel
dBA    dB adjusted
DBI    downlink block identifier
dBI    dB referenced to an isotropic antenna
dBI    decibels above isotopic circular
dBM    dB below 1 milliwatt
DBS    direct broadcast satellite
DBU    database unit
DBU    dial backup
dBW    dB-watts or referenced to 1 watt
DC    disconnect confirm
DC    direct current
DCAS    digital control audio system
DCD    double channel duplex
DCE    data communications equipment
DCGF    data conversion gateway function
DCL    departure clearance (European)
DCMF    data communication management function
DCMS    data communication management system
DCN    document/drawing/design change notice
DCP    data communication process
DCP    display control panel
DCS    double channel simplex
DCU    data concentration unit
DCV    directional control valve
DD    data delivery
DDA    digital differential analyzer
DDD    dual disk drive
DDM    difference in depth of modulation
DDP    declarations of design and performance
DDR    draft document review
DDS    data link delivery of expected taxi clearances
DDS    direct digital synthesizer
DDT    downlink data transfer
DECCA    a navigation system widely used by European shipping
DER    designated engineering representative
DFA    direction finding antenna
DFCS    digital flight control system
DFDAF    digital flight data acquisition function
DFDAMU    digital flight data acquisition management unit
DFDAU    digital flight data acquisition unit
DFDR    digital flight data recorder
DFDU    digital flight data unit
DFIDU    dual function interactive display unit
DFIU    digital flight instrument unit
DFS    digital frequency select
DFS    Deutsche Flugsicherung GmbH (Germany)
DFU    digital function unit
DGNSS    differential GNSS
DGPS    differential GPS
DH    decision height
DI    data interrupt
DIFAX    digital facsimile
DIP    data interrupt program
DIR    director
DIR/INTC    direct intercept
DISC    disconnect
DISCH    discharge
DIST    distance
DITS    data information transfer system
DL    data link
DL    downlink
DLAP    data link application processor
DLC    data link control
DLCI    data link control identifier
DLE    data link entity
DLK    data link (AEEC)
DLL    data link layer
DLM    data link management unit
DLME    data link and message engineering
DL/MSU    data loader/mass storage unit
DLORT    data link operational requirements team
DLP    data link processor
DLS    data link service/system
DLU    download unit
DM    disconnected mode
DMA    direct memory access
DME    distance measuring equipment
DME/N    DME normal
DME/P    DME precision
DMM    data memory module
DMS    debris monitoring sensor
DMS    data link management system
DMU    data management unit
DoD    Department of Defense
DoT    Department of Transportation
DOTS    dynamic ocean tracking system
DPI    dots per inch
DPR    dual port RAM
DPSK    differential phase shift keying
DR    dead reckoning
DRAM    dynamic random access memory
DRER    designated radio engineering representative (FAA)
DRN    document release notice
DSAD    digital service access device
DSARC    defense system acquisition review cycle
DSB    double side band
DSB-AM    DSB, full carrier digital amplitude modulation
DSDU    data signal display unit
DSF    display system function
DSP    digital signal processor
DSP    display select panel
DSP    domain specific part
DSPDRV    display driver
DSR    display system replacement
DSS    decision support services
DSU    data signaling unit
DTD    data terminal display
DTD    document type definition
DT&E    development test and evaluation
DTE    data terminal equipment
DTG    distance-to-go
DTM    demonstration test milestone
DTMF    dual tone multifrequency (telephone)
DTPDU    data protocol data unit
D-TOC    digital transfer of communications
DTU    data transfer unit
DU    display unit
DUAT    direct user access terminal
DVD    digital video disc
DVF    demonstration and validation facility
DVM    digital voltmeter
DWAN    direct WAN



EAA    Experimental Aircraft Association
EACARS    enhanced ACARS
EAD    European AIS data base (Eurocontrol)
EADI    electronic attitude director indicator
EAI    engine anti-ice
EANPG    European Air Navigation Planning Group
EAP    engine alert processor
EAROM    electrically alterable ROM
EAS    equivalent airspeed
EARTS    en route automated radar tracking system
EASIE    enhanced ATM and Mode S implementation in Europe
EATCHIP    European air traffic control harmonization & integration program
EATMS    European ATM System (Eurocontrol)
ECAC    European Civil Aviation Conference
ECACNAV    Eurocontrol navigation Web site
ECAM    electronic caution alert module
ECC    error correcting code
ECEF    earth-centered, earth-fixed
ECL    emitter coupler logic
ECL    engine control lever

ECMP    electronic component management system
ECN    engineering change notice
ECO    engineering change order
ECP    EICAS control panel
ECP    engineering change proposal
ECS    engineering compiler system
ECS    environmental control system
ECS    event criterion subfield
ECSL    left environmental control system card
ECSMC    ECS miscellaneous card
ECSR    right environmental control system card
ED    EICAS display
E/D    end-of-descent
EDA    electronic design automation
EDAC    error detection and correction
EDARC    enhanced direct access radar channel
EDC    error detection and correction
EDDS    electronic document distribution service
EDI    electronic data interchange
EDI    engine data interface
EDIF    engine data interface function
EDIU    engine data interface unit
EDMS    electronic data management system
EDP    electronic data processing
EDP    engineering development pallet
EDP    engine driven pump
EDS    explosive detection system
EDU    electronic display unit
EE    electrical engineer
EE    electronics equipment
EEAS    enhanced en-route automation system
EEC    Eurocontrol Experimental Center
EEC    electronic engine control
EEPROM    electrical erasable programmable ROM
EEU    ELMS electronics unit
EFB    electronic flight bag
EFC    expected further clearance
EFD    electronic flight display
EFDAS    European logical flight data server(Eurocontrol)
EFDP    European flight data processing(Eurocontrol)
EFIC    electronic flight instrument controller
EFIP    electronic flight instrument processor
EFIS    electronic flight instrument system
EFIS CP    EFIS control panel
EGIHO    expedited ground-initiated handoff
EGNOS    European Geostationary Overlay System
EGP    exterior gateway protocol
EGPWS    enhanced ground proximity warning system
EGT    exhaust gas temperature
EHSI    electronic horizontal situation indicator
EHV    electro-hydraulic valve
EIA    Electronic Industries Association
EIA    Electrical Institute of America
EICAS    engine indication and crew alert system
EICASC    EICAS controls
EIPI    extended initial protocol identifier
EIRP    earth incident radiated power
EIS    electronic instrument system
EIS    engine indication system
EIS    environmental impact statement
EISA    extended industry standard architecture
EIU    electronic interface unit
ELEC    electrical
ELM    extended length message
ELMS    electrical load management system
ELS    electronic library system
ELT    emergency locator transmitter
EM    element manager
EM    electromagnetic
EMATS    endurance management air traffic system
EMC    electromagnetic compatibility
EMC    entertainment multiplexer controller
EMER    emergency
EMI    electromagnetic interference
EMS    emergency medical services
EMS    engine management system
ENG    engine
ENOC    engineering network operations center
E/O    engine-out
EOD    end of day
EOM    end of message
EOT    end of text
EP    engineering project
EP    external power
EPC    engineering project contractor
EPCS    engine propulsion control system
E-PIREPS    electronic pilot reports
EPLD    electronically programmable logic device
EPR    engine pressure ratio
EPROM    erasable programmable ROM
EPS    electrical power system
ERPDU    error protocol data unit
ERB    Engineering Review Board
ERD    end routing domain
ERP    eye reference point
ERP PDU    echo replay protocol data unit
ERQ PDU    echo request protocol data unit
ERU    engine replay unit
ES    end system
ESA    European Space Agency
ESAS    electronic situation awareness system
ESAS    enhanced situational awareness system
E-Scan    electronic scanning
ESD    electrostatic discharge
ESDS    electrostatic sensitive devices
ESH    end system hello
ESID    engine and system indication display
ESIS    engine and system indication system
ESS    environmental stress screening
ESS    electronic switching system
ESSD    electrostatic sensitive devices
ESU    environmental sensor unit
ETA    estimated time of arrival
ETAS    enhanced TRACON/tower automation system
ETB    end of block (ASCII/IA5 character)
ETB    engineering test bed
ETC    estimated time of completion
ETD    estimated time of departure
ETI    elapsed time indicator
ETM    elapsed time measurement
ETMS    engine-trend monitoring services
ETMS    enhanced traffic management system
ETOP    extended twin-engine operations
ETRC    expected taxi ramp clearances
ETVS    enhanced terminal voice switch
ETX    end of transmission
EUAFS    enhanced upper air forecast system
EUPS    external uninterruptible power supply
EURATN    European ATN
EURET    European research on transport systems
EUROCAE    European Organization for Civil Aviation Equipment (European equivalent of RTCA)
EV    earned value
EVM    error vector magnitude



F    fahrenheit
FA    final approach
FAA    Federal Aviation Administration (U.S.)
FAA/EURO    FAA/Eurocontrol R&D committee
FAATC    FAA Technical Center
FAC    flight augmentation computer
FADEC    full authority digital engine/electronic control
FAF    final approach fix
FAI    first article inspection
FANS    Future Air Navigation System (ICAO)
FAR    federal acquisition regulation
FAR    federal aviation regulation
FAST    final approach spacing tool
FAT    factory acceptance test
FBL    fly by light
FBO    fixed-base operator
FBW    fly by wire
FC    functional capability
FC    foot candles
FCA    functional configuration audit
FCC    flight control computer
FCC    Federal Communications Commission
FCDC    flight critical direct current
FCP    flight control processor
FCP    flight control panel
FCS    frame check sequence
FD    flight dynamics/director
FD    final data
FDAF    flight data acquisition function
FDAU    flight data adquisition unit

FDB    flight plan data bank
FDDI    fiber distribution data interface
FDEP    flight data entry panel
FDH    flight deck handset
FDI    fault detection and isolation
FDIMU    flight data interface management unit
FDIO    flight data input/output
FDM    frequency division multiplex
FDMA    frequency division multiple access
FDPS    flight data processing system
FDR    flight data recorder
FDRS    flight data recorder system
FDP    flight data processor
F&E    facilities and equipment
FEATS    future European air traffic management system
FEC    forward error correction
FEP    front-end processor
FF    fuel flow
FFIC    free flight implementation committee
FFS    full flight simulator
FGC    flight guidance computer
FHA    functional hazard assessment
FIB    forwarding information base
FIFO    first in, first out
FIR    flight information region
FIS    flight information services
FIS-B    FIS-broadcast
FIX    position in space usually on aircraft’s flight plan
FL    flight level
FL    foot lampert
FLCH    flight level change
FLIR    forward-looking infrared
FLW    forward-looking windshear radar
FM    frequency modulation
FMA    flight mode annunciator
FMAC    Frequency Management Advisory Council
FMC    flight management control/computer
FMCF    flight management computer function
FMCS    flight management computer system
FMCW    frequency-modulated continuous wave
FMEA    failure mode and effects analysis
FMF    flight management function
FMP    flight mode panel
FMS    flight management system
FMSG    Frequency Management Study Group (ICAO)
FMU    fuel metering unit
F/O    first officer
FOC    full operational capability
FOC    fuel/oil cooler
FODA    flight operations data assurance
FOG    fiber optic gyro
FOQA    flight operational quality assurance
FOV    field of view
FPA    focal plane array
FPA    flight path angle
FPAC    flight path acceleration
FPC    flight profile comparator
FPGA    field programmable gate array
FPM    feet per minute
FPV    flight path vector
FQIS    fuel quality indicating system
FQPU    fuel quality processor unit
FQR    formal qualification review
FR    frame relay
FRA    flap retraction altitude
FRAD    frame relay access device
FRM    frame reject mode
FRMR    frame reject
FRP    Federal Radionavigation Plan
FRPA    fixed reception pattern antenna
FRQ    frequency
FSAS    flight service automation system
FSE    FANS systems engineering
FSE    field service engineer
FSEMC    Flight Simulator Engineering and Maintenance Conference
FSEU    flap slat electronics unit
FSF    Flight Safety Foundation
FSM    flight schedule monitoring
FSS    flight service station
FSWE    FANS software engineering
FT    functional test
FTE    flight technical error
FTP    file transfer protocol
FTPP    fault tolerant power panel
FVHF    future VHF system study (Eurocontrol)
FW    failure warning
FW    firewall router
FWC    flight warning computer
FWD    forward
FWS    flight warning system
FY    fiscal year



G/A    ground/air or ground-to-air
GA    general aviation
GA    go-around
GAAS    gallium arsenide
GACS    genetic ATN communications service
GAIT    ground-based augmentation and integrity technique
GAMA    General Aviation Manufacturers Association
GAO    General Accounting Office
GATM    global ATM
GBAS    ground-based augmentation system
GBST    ground based software tool
Gbyte    gigabyte (billion bytes)
GCA    ground-controlled approach
GCAS    ground collision avoidance system
GCB    generator circuit breaker
GCC    ground cluster controller (ACARS)
GCS    ground clutter suppression
GCU    generator control unit
GDAP    growing danger of acronym proliferation
GDLP    ground data link processor
GDOP    geometric dilution of precision
GDP    ground delay program
GENOT    general notice
GEO    geosynchronous/geostationary earth orbit
GEP    ground entry point
GES    ground earth station
GFE    government furnished equipment
GFI    general format identifier
GFSK    Gaussian frequency shift keying
GG    graphics generator
G/G    ground/ground
GGR    G/G router
GGS    GPS ground station
GGTFM    ground-ground traffic flow management
GH    ground handling
GHz    gigahertz
GI    group identifier
GIB    GNSS integrity broadcast
GIC    GNSS integrity channel
GIC    GPS integrity channel
GICB    ground-initiated comm-B
GIHO    ground initiated handoff
GIP    government-industry partnership
GIS    geodetic information system
GIS    graphical information system
GL    ground location (ACARS/AFEPS)
GL    group length
GLC    geographic locator codes
GLNS    GPS landing and navigation system
GLONASS    Global Navigation Satellite System (Russia)
GLS    GPS landing system
GLU    GPS landing unit
GM    guidance material
GMC    ground movement control
GMDS    ground mobile data service
GMT    Greenwich mean time
GMU    GPS monitoring unit
GNA    global network architecture
GNE    gross navigational error
GNR    global navigation receiver
GNSS    global navigation satellite system
GOS    grade of service
GOSIP    government open systems interconnection profile
GPADIRS    global positioning, air data, inertial reference system
GPCBT    guidelines for the production of computer-based training (Eurocontrol)
GP&C    global positioning and communications
GPIB    general purpose instrument bus
GPP    general purpose processor
GPS    Global Positioning System (Navstar)
GPS L1    GPS L1 frequency
GPSSU    GPS sensor unit
GPU    ground power unit
GPWC    ground proximity warning computer
GPWS    ground proximity warning system
GR    ground router
GRIP    gridded binary (National Weather Service model output)
GRP    geographic reference point
GS    ground speed/station
G/S    glideslope
GSC    ground station controller (ACARS)
GSE    ground support equipment
GSIF    ground station information frame
GSM    global systems mobile
GSMS    ground station management system
GSP    glare shield panel
GTC    data link ground terminal computer
GUI    graphical user interface
GVE    graphics vector engine
GW    gateway
GWS    graphical weather services



HAD    hardware architecture document
HARS    high altitude route system
HCI    human-computer interface
HCP    heads-up control panel
HDG    heading
HDG SEL    HDG select
HDISK    hard disk
HDL    hybrid data link
HDLC    high-level data link control
HDLC-B    HDLC-balanced
HDLMS    hybrid data link management system
HDOP    horizontal dilution of precision
HDP    hardware development plan
HDTV    high-definition television
HE    altitude error
HF    high frequency
HF    human factors
HFDL    high frequency data link
HFDM    high-frequency data modem
HFDR    high frequency data radio
HFI    human factors integration
HFNPDU    high frequency network protocol data unit
HFS    high frequency system
HFSG    human factor study group
HFSNL    high frequency subnetwork layer
HFWG    human factors working group
HGA    high gain antenna
HGAS    HGA system
HGC    head-up guidance computer
HGS    head-up guidance system
HGS    HFDL ground station
HHLD    heading hold
HIL    horizontal integrity limit
HIRF    high intensity radiated field
HLCS    high lift control system
HLE    higher layer entity
HLL    high level language
HMI    human-machine interface
HMOS    high density metal oxide semiconductor
HMU    height monitoring unit
HO    handoff
HOCSR    host/oceanic computer system replacement
HOW    hand-over word
HP    high pressure
HP    holding pattern
hPa    hecto Pascal
HPA    high power amplifier
HPC    high pressure compressor
HPR    high power relay
HPSOV    high pressure shutoff valve
HPT    high pressure turbine
HRD    home routing domain
HRM    home regional manager
HS-DSAD    high speed frame relay service access device
HSI    horizontal situation indicator
HSIT    hardware and software integration test
HSL    heading select
HSR    high stability reference
HSRP    hot standby routing protocol
HTC    highest two-way channel
HUD    head up display
HVPS    high voltage power supply
HWCI    hardware configuration item
HX    heat exchanger
HYD    hydraulic
HYDIM    HYD interface module
Hz    Hertz (cycles per second)



I&TE    integration and test engineering
IACSP    international aeronautical communications service provider
IAGS    integrated ARINC ground station
IANA    Internet assigned number authority
IAOA    indicated angle of attack
IAOPA    International Council of Aircraft Owners and Pilots Association
IAPS    integrated avionics processing system
IARP    inverse address resolution protocol
IAS    indicated airspeed
IAT    investment analysis team
IATA    International Air Transport Association
IBAC    International Business Aviation Council
IC    integrated circuit
IC    intercabinet
ICAO    International Civil Aviation Organization
ICARD    ICAO five-letter name code & route designator system
ICC    IAPS card cage
ICCAIA    International Coordinating Council of Aerospace Industries Association
ICD    interface control document/drawing
ICD    interactive design center
ICD    installation control drawing
ICM    interline communications manual
ICMP    Internet control message protocol
ICNIA    integrated communications, navigation and identification avionics
ICS    interface control specification
ICSS    integrated communication switching system
ICU    integrated control unit
ICU    instrument comparator unit
ID    identifier/identification
IDC    internal diagnostic capabilities
IDC    indicator display/control
IDD    interface design document
IDEN    integrated digital enhanced network
IDG    integrated drive generator
IDI    initial domain identifier
IDP    initial domain part
IDRP    interdomain routing protocol
IDS    integrated display system
IDS    inter-domain system
IDS    ice detection system
IDU    interactive display unit
IEC    International Electrotechnical Commission
IEC    IAPS environmental control module
IEC    International Engineering Consortium
IED    insertion extraction device
IEEE    Institute of Electrical and Electronics Engineers
IF    intermediate frequency
IFALPA    International Federation of Airline Pilots Association
IFATCA    International Federation of Air Traffic Controllers’ Association
IFC    indicated final cost
IFE    in-flight entertainment
IFPS    integrated initial flight plan processing system
IFR    instrument flight rules
IFRB    International Frequency Registration Board
IGES    intermediate ground earth station
IGES    standardized graphics exchange file
IGIA    Interagency Group on International Aviation
IGV    inlet guide vane
ILA    International Law Association
ILM    independent landing monitor
ILS    instrument landing system
ILSP    integrated logistics support plan
IMA    integrated modular avionics
IMC    instrument meteorological conditions
IMG    implementation manager group
INFO    information frame
INAV    interactive navigation
IN.HG.    inches of mercury
INMARSAT    International Maritime Satellite Organization
INMS    integrated network management system
INS    inertial navigation system
INTELSAT    International Telecommunications Satellite Organization
InterNIC    Internet Network Information Center
I/O    input/output
IOC    initial operating capability
ION    Institute of Navigation
IOR    Indian Ocean region
IOS    Internet operating system
IOT & E    initial operational test and evaluation
IP    Internet protocol
IPACG    Informal Pacific ATC Coordination Group
IPC    interprocess communication
IPC    intermediate pressure compressor
IPD    industrial products division
IPI    initial protocol identifier
IPL    illustrated parts list
IPR    Internet protocol router
IPT    integrated product team
IPT    intermediate pressure turbine
IR    infrared
IRAC    Interdepartmental Radio Advisory Committee
IRP    integrated refuel panel
IRR    internal rate of return
IRS    inertial reference system
IRS    interface requirements specification
IRU    inertial reference unit
IS    intermediate system
ISA    industry standard architecture
ISA    Instrument Society of America
ISC    integrated systems controller
ISDN    integrated services digital network
ISDOS    information system design and optimization system
ISH    intermediate system hello
ISLN    isolation
ISO    International Standards Organization
ISO PA    ISO protocol architecture
ISP    integrated switching panel
ISR    interrupt service routine
ISSN    intermediate system subnetwork
ISSS    initial sector suite system/subsystem
ISU    initial signal unit
IT    information technology
ITM    IT management
ITS    integrated test system
ITSE    integrated test and support environment
ITU    International Telecommunications Union
ITWS    integrated terminal weather system
IUPS    internal uninterruptible power supply
IV    isolation valve


JAA    Joint Aviation Authority
JAR    joint airworthiness requirement
JAR-AWO    JAR-all weather operations
JATO    jet assisted takeoff
JCAB    Japanese Civil Aviation Bureau
JFET    junction field effect transistor
JPS    journal processing system
JRC    Joint Resource Council
J/S    jammer-to-signal ratio
JSAT    joint system acceptance test
JTAG    Joint Test Action Group
JTIDS    joint tactical information distribution system
JV    joint venture



KB    kilobytes (thousand bytes)
KBITS    kilobits
Kbps    kilobits per second
kgls    kinematic GPS landing system
KHz    kilohertz (1000 cycles per second)
KPS    KB per second
KTS    knots
KVA    kilovolt-ampere
KW    kilowatt



L1    L-band carrier (1575.42 MHz)
L2    L-band carrier (1227.6 MHz)
LAAS    local area augmentation system
LACAC    Latin American Civil Aviation Commission
LADGPS    local area differential GPS
LAHSO    land and hold short operation
LAN    local area network
LAPB    link access protocol, balanced
LAT    latitude
LBA    Luftfahrt-Bundesamt (Germany)
LCA    layered component architecture
LCC    leadless chip carrier
LCD    liquid crystal display
LCF    link control field
LCI    logical channel identifier
LCN    local communications network
LCP    lighting control panel
LCR    link connection refusal
LDA    landing directional aid
LDA    laterally displaced approach
LDCC    leaded chip carrier
LDCS    local departure control system
LDGPS    local area differential global positioning satellite
lDOC    long distance operational control
LDRCL    low density radio _ communications link
LDU    lamp driver unit
LE    link establish
LED    light-emitting diode
LEO    low earth orbiting
LF    low frequency
LFR    LF radio range
LGA    low gain antenna
LHP    lighting HIRF protection
LIMNATRAN    limited North Atlantic regional air navigation
LINCS    long-haul/leased interfacility national airspace communications system
LISN    line impedance stabilization network
LLC    logical link control
LLWAS    low-level windshear alert system
LME    link management entity
LMI    logical management interface
LMM    locator middle marker
LMT    local mean time
lNA    low-noise amplifier
LNAV    lateral navigation
LOB    left outboard
LOC    localizer/location
LOM    locator outer marker
LON    longitude
LORAN    long-range air navigation
LOS    line of sight
LPB    loss prevention bulletin
LPC    low pressure compressor
LPDU    link protocol data unit
LPT    low pressure turbine
LRC    long-range cruise
LRM    line replaceable module
LRR    long-range radar
LRU    line replaceable unit
LSB    least significant bit
LSB    lower sideband
LSD    least significant digit
LS-DSAD    low speed frame relay service access device
LS-FRAD    low speed frame relay access device
LSI    large scale integration
LSK    line select key
LSN    local subnetwork
LSP    link state PDU
LTC    lowest two-way channel
LV    lower sideband voice
LVL    level
LVDT    linear voltage differential transducer
LVPS    low voltage power supply



M    mach number
MA    message assurance
MAA    maximum authorized IFR altitude
MAC    medium access controller
MACC    military area control center
MACS    multiple access communication system
MAHWP    missed approach holding waypoint
MALDT    mean administrative and logistics delay time
MAN    metropolitan area network
MAP    missed approach
MAPt    missed approach point
M/ASI    mach/airspeed indicator
MASPS    minimum aviation system performance standards
MAST    multiaircraft simulation terminal
MAT    maintenance access terminal
MAV    micro air vehicle
MAWP    missed approached waypoint
MAX    maximum
MB    marker beacon
MBE    multiple bit error
MBER    minimum bit error rate
MBPS    megabytes per second
MC    master change
MCA    minimum crossing altitude
MCB    microwave circuit board
MCC    maintenance control computer
MCDP    maintenance control display panel
MCDU    multifunctional control display unit
MCN    manufacturing control number
MCP    maintenance control panel
MCT    max continuous thrust
MCU    multifunction/modular concept unit
MDA    minimum descent altitude
MDC    maintenance diagnostic computer
MDCRS    Meteorological Data Collection and Reporting Service
MDL    multipurpose data link
MDR    mode digital radio
MDS    minimum discernible signal
MDT    maintenance display terminal
MDT    mean downtime
MEA    minimum en route altitude
MEC    main equipment center
MEL    minimum equipment list
MEO    medium earth orbit
MES    main engine start
MET    meteorology
METAR    meteorological aviation routine weather report
MF    medium frequency
MFCP    multifunction control display panel
MFD    multifunction display
MFDS    MFD system
MFDU    MFD unit
MFIT    mean fault isolation time
MFM    maintenance fault memory
MGSCU    main gear steering control unit
MGR    manager
MHD    magnetic hard drive
MHS    message handling service
MHz    megahertz
MIB    management information base
MIC    microphone
MicroEARTS    micro en route automated radar tracking system
MIDU    multi-purpose interactive display unit
MILSPEC    military specification
MIL-STD    military standard
MIMO    multi-input/multi-output
MIN    minimum/minute
MIPS    management interface protocol specification
MIPS    million instructions per second
MKR    marker
MLA    maneuver limited altitude
MLM    mid-level management
MLS    microwave landing system
MLW    maximum landing weight
MM    mass memory
MMI    man-machine interface
MMIC    monolithic microwave integrated circuit
MMR    multimode receiver
MMS    maintenance management system
MMW    millimeter wave
MNCID    management network category interaction diagram
MNPS    minimum navigation performance specification
MNS    managed network service
MO    managed object
MO    magneto-optical
MOA    military operation area
MOA    memorandum of agreement
MOCA    minimum obstacle clearance altitude
MOD    modification
MOD    magneto-optical drive
MODEM    modulator/demodulator
MOPR    minimum operational performance requirements
MOPS    minimum operational performance standards
MORA    minimum off-route altitude
MOS    metal oxide semiconductor
MOU    memorandum of understanding
MPAR    multipurpose airport radar
MPCU    multiport protocol converter unit
MPEL    maximum permissible exposure level
MPS    maintenance processor system/ subsystem
MRA    minimum reception altitude
MRR    manufacturing revision request
MRT    mean repair time
Ms    millisecond
MSB    most significant bit
MSC    message sequence chart
MSCP    mobile satellite service provider
MSD    mass storage device
MSG    message
MSI    medium scale integration
MSK    minimum shift keying
MSL    mean sea level
M-SNDCF    mobile-subnetwork dependent convergence function
MSP    Mode S specific protocol
MSSR    monopulse secondary surveillance radar
MSSS    Mode S specific services
MSU    mode select unit
MT    minimum time
MTA    message transfer agent
MTBF    mean time between failures
MTBO    mean time between outages
MTBR    mean time between removal/repairs
MTTR    mean time to repair
MTTRS    mean time to restore service
MTBUR    mean time between unscheduled removal
MTBUR    mean time between unit replacements
MTC    maintenance terminal cabinet
MTD    maintenance terminal display
MTF    maintenance terminal function
MTI    moving target indicator
MTM    module test and maintenance
MTMBIU    MTM bus interface unit
MTTDA    mean time to dispatch alert
MTTF    mean time to failure
MTTM    mean time to maintenance
MTTMA    mean time to maintenance alert
MTTR    mean time to repair
MTTUR    mean time to unscheduled removal
MU    management unit
MUS    minimum use specification
MUSE    multiuser system environment
MUX    multiplexer
MWARA    major world air route area



N1    fan speed
N2    intermediate compressor speed
N3    high-speed compressor
N/A    not applicable
NACA    National Advisory Committee for Aeronautics
NCAR    National Center for Atmospheric Research
NADIN    national airspace data interchange network
NADIN II    NADIN packet switch
NAILS    national airspace integrated logistics support
NAK    negative acknowledgment
NAS    national airspace system (FAA)
NAS    national aircraft standard
NASA    National Aeronautics and Space Administration
NASPALS    national airspace system precision approach and landing system
NAT    North Atlantic region
NAT    North Atlantic tracks
NATA    National Air Transport Association Inc.
NATCA    National Air Traffic Controllers Association
NAT/NAM/PAC    North Atlantic/North American/Pacific
NATS    National Air Traffic Services (UK)
NATS    North Atlantic track system
NAT TFG    NAT Traffic Forecasting Group
NAV    navigation
NAVAID    navigational aid
NBAA    National Business Aircraft Association
NC    numerical control
NCD    no computed data
NCI    not currently implemented
NCP    NAS change proposal
NCS    network control system
NCS    network coordination station
ND    navigation display
NDB    non-directional radio beacon
NDI    nondestructive inspection
NDI    non-developmental item
NE    network element
NEMA    National Electrical Manufacturers Association
NESDIS    national environmental satellite data and information service
NET    network entity title
NEXCOM    Next generation air/ground Communications system
NEXRAD    next-generation weather radar
NFF    no fault found
NIAC    NAS Information Architecture Committee (FAA)
NICE    NAT implementation management group cost effectiveness
NIMS    NAS infrastructure management system
NIR    network interface router
NIRV    network interface router VDL
NIS    not in service
NISC    NAS information security coordination
NIST    National Institute of Standards and Technology
NIU    North American ISDN User Forum (NIST)
NIP    network interface processor
NL    network layer
NLM    network loadable module
NLP    network layer protocol
NLR    Netherlands National Aerospace Laboratory
NM    network management
NM    nautical mile
NMC    National Meteorological Center
NMCCD    network management category class diagram
NMCD    network management category diagram
NMF    network management function
NMIRS    network management interface requirements specification
NMP    network management plan
NMS    network management system
NOAA    National Oceanic and Atmospheric Administration
NOC    network operations center
NOC    note of change
NOCAR    North Atlantic oceanic concept and requirements
NOCC    national operational control center
NO COM    no communication
NOI    notice of inquiry (FCC)
NOPAC    North Pacific
NOTAM    notice to airmen
NOTUS    notice to users (ARINC)
NPA    non-precision approach
NPDU    network protocol data unit
NR    network router
NRD    network routing domain
NRP    national route program
NRZ    non-return to zero
NS    network service
NSAP    network service access point
NSC    network service center
NSDU    network service data unit
NSEL    NSAP selection
NSEU    neutron single event upset
NSSL    National Severe Storms Laboratory
NTIA    National Telecommunications and Information Administration (U.S.)
NTF    no trouble found
NTSM    National Transportation Safety Board (U.S.)
NUI    network user identification
NVM    non-volatile memory
NVRAM    non-volatile RAM
NWS    National Weather Service (U.S.)



O&M    operations and maintenance
OAC    oceanic area control center
OAS    oceanic automation system
OASIS    operational and supportability implementation system
OASYS    obstacle avoidance system
OAT    operational acceptance test
OAT    outside air temperature
OATS    orbit and attitude tracking system
OBP    operational build plan
OBS    omnibearing selector
OBS    optical bypass switch
OCA    oceanic control area
OCC    operations control center
OCD    oceanic clearance delivery
OCIG    Oceanic Communications Improvement Group
OCP    oceanic clearance processor
ODA    open document architecture
ODAPS    oceanic display and planning system
ODIAC    operational requirements for ATM air/ground data communications (Eurocontrol)
ODID    operational display and input development
ODL    optical data link
ODL    oceanic data link
OEM    original equipment manufacturer
OEU    overhead electronics unit
OFDM    orthogonal frequency division multiplexing
OFDPS    oceanic flight data processing system
OFP    operational flight program
OGE    operational ground equipment
OHU    overhead unit (HUD)
OID    object identifier
OJT    on-the-job training
OLAN    onboard local area network
OLDI    on-line data interchange
OM    outer marker
OMB    Office of Management and Budget (U.S.)
OMS    onboard maintenance system
OMT    object modeling technique
OOA    object-oriented analysis
OOD    object-oriented design
OOOI    out/off/on/in
OPAS    overhead panel ARINC 629 system
OPBC    overhead panel bus controller
OPS    operations
OPS    OPS per second
OPSPECS    OPS specifications
OPU    overspeed protection unit
O-QAR    optical quick access recorder
OR    operational requirements
ORD    operations readiness demonstration
ORD    operational requirements document
OS    operating system
OSDS    oceanic systems development support
OSE    open systems environment
OSI    open systems interface/ interconnection
OSIE    OSI environment
OSI-RM    OSI reference model
OSPF    open shortest path first
OSR    order status report
OTA    Office of Technology Assessment (U.S.)
OT&E    operational test and evaluation
OTFP    operational traffic flow planning
OTH    over the horizon
OTP    Office of Telecommunications Policy (U.S.)
OTS    off the shelf
OVHT    overheat



P2FEP    PETAL-II front-end processor
P3 I    preplanned product improvements
PA    passenger address
PA    power amplifier
PAC    path attenuation compensation
PACIS    passenger address and communication interphone system
PAD    packet assembler-disassembler
PAL    programmable array logic
PAM    pulse amplitude modulation
PAMRI    peripheral adapter module replacement item
PANS-OPS    procedures for air navigation services-aircraft operations
PAR    precision approach radar
PAT    process action team
PAU    passenger address unit
PAWES    performance assessment and workload evaluation
PAX    passenger
PBD    place bearing/distance (waypoint)
PBID    post burn-in data
PBX    public/private branch exchange
PC    printed circuit
PC    personal computer
PCA    physical configuration audit
P-Code    GPS precision code
PCB    printed circuit board
PCC    pilot controller communication
PCI    peripheral component interface (32-bit local bus)
PCI    protocol control information
PCM    pulse code modulation
PCMIA    personal computer memory card interface association
PCO    protocol converter unit
PCU    program coordination office
PCU    passenger control unit
PCU    power control unit
PD    profile descent
PDB    performance data base
PDC    pre-departure clearance
PDCU    panel data concentrator unit
PDD    package design document
PDDI    product definition data interface
PDF    primary display function
PDL    program design language
PDM    predefined controller text message
PDM    project development manager
P-DME    precision DME
PDN    public data network
PDOP    position dilution of precision
PDR    preliminary design review
PDS    persistent data storage
PDS    primary display system
PDU    protocol data unit
PECT    peer entity contact table
PED    portable electronic device
PER    packed encoding rule
PERT    program evaluation and review technique
PETAL    preliminary Eurcontrol test of air/ground data link
P/F    poll/final
PF    power factor
PF    pilot flying
pFAST    passive final approach spacing tool
PFC    primary flight computer
PFCS    primary flight control system
PFD    primary flight display
PHARE    Program for Harmonized ATM research in Europe (Eurocontrol)
PHY    physical
PI    parameter identifier
PIA    performance, integrity and availability
PICS    protocol implementation conformance statements
PID    parameter identifier
PID    primitive identifier
PID    process ID
PIREP    pilot report
P&L    profit and loss
PL    parameter length
PL    project leader
PLA    power lever angle
PM    program manager
PM    phase modulation
PMA    parts manufacturer approval
PMA    permanent magnet alternator
PMAT    portable maintenance access terminal
PMC    provisional memory cover
PMC    PCI mezzanine card
PMG    permanent magnet generator
PMOS    p-type metal oxide semiconductor
PMP    project/program management plan
PMS    performance management system
PN    pseudo noise
PNCS    performance navigation computer system
PND    primary navigation display
PNF    pilot not flying
PNR    point of no return
PO    part of
POA    plain old ACARS
POC    point of contact
POC    proof of concept
POH    pilot’s operating handbook
POP    point of presence
POR    Pacific Ocean region
POTS    plain old telephone system/service
PPDU    physical layer protocol data unit
PPI    planned position indicator
PPL    processor-to-processor link
PPM    pulse position modulation
PPM    pages per minute
PPM    parts per million
PPP    point-to-point protocol
PPS    packets per second
PPS    pulse per second
PPS    precise positioning service
PRAIM    predictive RAIM
PRF    pulse repetition frequency
PRI    primary rate interface
PRM    precision runway monitor
PROM    programmable ROM
PRN    pseudo random noise
PRSOV    pressure regulating and shutoff valve
P/RST    press to reset
PS    power supply
PSA    PS assembly
PSD    port sharing device
PSDN    packet switched data network
PSE    packet-switching exchange
PSEU    proximity sensor electronic unit
PSL    projected service life
PSL/PSA    problem statement language/ problem statement analyzer
PSM    power supply modules
PSN    packet switching network
PSPL    preferred standard parts list
PSR    primary surveillance radar
PSS    proximity sensor system
PSTN    public switched telephone network
PSU    passenger service unit
PT    total pressure
PTD    performance test domain
PTI    packet type identifier
PTM    peripheral transition module (I/O interface for SBC)
PTR    production test requirements
PTS    problem tracking system
PTSD    production test specification document
PTT    push to talk
PTU    power transfer unit
PV    parameter value
PVC    permanent virtual circuit
PVD    plan view display
PVT    position, velocity, time
PWM    pulse-width modulation
PWR    power



QA    quality assurance
QAP    QA plan
QAR    quick access recorder
QDR    quality defect report
QDR    quality deficiency report
QEC    quadrantral error corrector
QM    quality management
QMP    QM plan
QMS    QM system
QOP    quality operating procedures
QRH    quick reference handbook
QOS    quality of service
QP    quality procedure
QT    qualification test
QVL    qualified vendor list



RA    routing area
RAA    Regional Airline Association
RAAF    Royal Australian Air Force
RAC-GAT...    Russian/American Coordinating Group for Air Traffic Control.
RAD    rapid application development
RAF    requirements analysis folder
RAF    Royal Air Force (UK)
RAI    radio altimeter indicator
RAIM    receiver autonomous integrity monitoring
RALA    request automatic line adapter
RALT    radar altimeter
RAM    random access memory
RCE    radio control equipment
RCL    radio communications link
RCO    remote communications outlet
RCP    radio control panel
RCR    routing and circuit restoral
RCU    remote control unit
RC&W    rack connectors and wiring
R&D    research and development
RD    routing domain
RDARA    regional domestic air route area
RDC    routing domain confederation
RDF    RD format
RDI    RD identifier
RDP    radar data processing
RDR    radar
RDSS    radio determination satellite system
RDT&E    research, development, test and evaluation
RE&D    research, engineering and development
REDAC    Research, Engineering and Development Advisory Committee (FAA)
REQ    request
RER    residual error rate
RF    radio frequency
RFC    request for comments
RFI    radio frequency interference
RFI    request for information
RFO    request for offer
RFP    request for proposal
RFQ    request for quote
RFU    radio frequency unit
RGB    red green blue
RGCSP    Review of the General Concept of Separation Panel (ICAO)
RGS    relay ground station
RH    radio handler
RHF    ridiculously high frequency
RHO    response on handoff
R&M    reliability and maintainability
RHSM    reduced horizontal separation minima
RIB    routing information base
RIP    routing information protocol
RISC    reduced instruction set computer
RLE    response on link establishment
RLS    reliable link service
RM    regional manager
RM&A    reliability, maintainability and availability
RMI    radio magnetic indicator
RMMS    remote maintenance monitoring system
RMP    risk management plan
RMS    risk management system
RMS    root mean square
RNAV    area navigation
RNP    required navigational performance
RNR    receive not ready
RO    radio operator
ROA    recognized operating agency
ROC    rate of climb
ROC    rest of operational capability
ROD    rate of descent
ROM    read only memory
ROM    rough order of magnitude
RON    remain over night
RP    routing protocol
RPDE    rapid preliminary development effort
RPM    revolutions per minute
RPOA    Recognized Private Operation Agency (CCITT)
RR    receive ready
RRI    router reference implementation
RSDP    reliable sequencing delivery-confirmation protocol
RSN    regional subnetwork
RSP    required surveillance performance
RSSI    received signal strength indicator
RT    radio telecommunication
RTA    required time of arrival
RTC    red time clock
RTCA    Radio Technical Commission for Aeronautics
RTCM    Radio Technical Commission for Maritime Services
RTK    real-time kinematic
RTM    radio transmission module
RTOS    real time operating system
RTO    rejected takeoff
RTR    remote transmitter receiver site
RTS    request to send
RTTI    run-time type identification
RTU    radio tuning unit
RU    rack unit (1 inch)
RVR    runway visual range
RVSM    reduced vertical separation minimum
R/W    read/write
RWM    R/W memory
RWR    radar warning receiver
RX    receiver
RZ    return to zero



S0    Segment 0
S1    Segment 1
SA    selective availability
SA    situational awareness
SABENA    Societe Anonyme Belge d’Exploitation de la Navigation Aerienne
SAD    software architecture document
SADT    software architecture design team
SAE    Society of Automotive Engineers
SAI    System Architecture and Interfaces Subcommittee (AEEC)
SAM    slot allocation management
SAM    South American region
SAP    service access points
SAPPHIRE    satellite and aircraft database program for system integrity research
SAR    search and rescue
SARPS    standards and recommended practices (ICAO)
SAS    station address set
SASS    surveillance analysis support system (Eurocontrol)
SAT    systems and acceptance testing
SATCOM    satellite communications
SATNAV    satellite navigation
SB    service bulletin
SBAS    satellite-based augmentation system
SBC    single board computer
SBD    schematic block diagram
SC    special committee (RTCA)
SCAT    special category
SCCI    system controller and cockpit indicator
SCD    system category diagram
SCPC    single carrier per channel
SCSI    small computer system interface
SDD    system/software design document
SDDN    software-defined data network
SDF    software development folder
SDI    source destination identifier
SDLC    synchronous data link control
SDM    software development methodology
SDP    software development plan
SDR    system design review
SDRAM    synchronous dynamic random access memory
SDU    satellite data unit
SE    systems engineering
SEI    Software Engineering Institute
SEL    select identifier
SELCAL    selective calling
SEMP    system engineering management plan
SETA    system engineering and technical assistance (contractor)
SEWG    security working group
SFDF    subsystem fault detection function
SFE    supplier-furnished equipment
SFT    software fault tolerance
SICAS    secondary surveillance radar improvements and collision avoidance systems
SID    standard instrument departure
SIGMET    significant meteorological information
SI&T    software integration and test
SISG    Systems Implementation Subgroup (IATA)
SIT    system integration and test
SITA    Societe Internationale de Telecommunications Aeronautiques
SITD    system integration test description
SITP    system integration test plan
SITP/D    SITP/description
SITR    system integration test report
SLA    service level agreement
SLC    synchronous link control
SLH    system level health
SLI    system level interface
SLM    standard length message
SLoC    source lines of code
SLUC    system level use case
SLV    service level verifier
SM    systems management
SMA    surface movement advisor
SMART    standard modular avionics repair and test
SMB    serial mezzanine board
SMD    surface mount device
SMDS    switch multimegabit data service
SME    system management entity
SMGCS    surface movement guidance and control systems
SMI    standard message identifier
SMR    specialized mobile radio
SMS    spectrum monitoring system
SMT    standard message text
SN    subnetwork
SNA    system network architecture
SNAC    SN access
SNCR    SN connection reference
SNDCF    SN dependent convergence function
SNDCF/P    SNDCF/protocol
SNICF    SN independent convergence function
SNLE    SN link establishment
SNMP    simple network management protocol
SNMPv1    SNMP version 1
SNPA    SN point of attachment
SNPDU    SN protocol data unit
SNR    signal-to-noise ratio
SNSDU    SN service data unit
SOH    start of header
SOI    system operator instructions
SOIA    simultaneous offset instrument approach
SOM    software operator manual
SOIT    satellite operational implementation team
SON    statement of operational need
SOW    statement of work
SPCR    system problem/change report
SPICE    STANS preparation integrator for CNS/ATM environment (Eurocontrol)
SPM    software programmer’s manual
SPS    software product specification
SPS    standard positioning service
SQ    service quality
SQAP    software quality assurance plan
SQB    SQ/billing processor
SQD    SQ data
SQP    signal quality parameter
SRAM    static random access memory
SREJ    selective reject
SRM    selective reject mode
SRR    system/software requirements review
SRS    software requirements specification
SRU    shop replaceable unit
SSA    source selection activity
SSAC    source selection advisory committee
SSB    single side band
SSDD    system/segment design document
SSEB    source selection evaluation board
SSR    secondary surveillance radar (ICAO/FAA)
SSS    surveillance server system
SSS    system/segment specification
SSU    subsequent signal unit
STANAG    standardization agreement
STANS    simulation for a total air navigation system (Eurocontrol)
STAR    standard terminal arrival route
STARS    standard terminal automation replacement system (FAA)
STB    systems test bed
STC    supplemental type certificate (FAA)
STCA    short-term traffic advisory
STD    standard
STD    system technical description
STDMA    synchronized time division multiple access
STF    SATCOM tracking facility
STIU    satellite telecommunications intermediate unit
STM    serial transition module
STP    system test plan
STP/D    STP/description
STR    system technical report
STR    system test report
STVS    small tower voice switch
STX    start of text
SU    signal unit
SUA    special use airspace
SUM    software user manual
SUPPS    regional supplementary procedures
SUT    system under test
SVC    switched virtual circuit
SvRR    service readiness review
SVU    satellite voice unit
SW    software
SWIT    software integration and test
SWIT    switched virtual circuit
SWTP    software technology plan
SWTRR    software test readiness review
SYS    system identifier
SYSCAT-B    system category-B (FAA message format)
SysCI    system configuration item
SysDD    system design document



TA    traffic advisory (TCAS)
TACAN    tactical air navigation
TAF    terminal aerodrome forecast
TAF    terminal area forecast (ICAO)
TAOARC    Terminal Area Operations Aviation Rulemaking Committee (FAA)
TAR    trials ATN router
TAP    tower automation program
TASS    terminal air surveillance system
TAWS    terrain avoidance warning system
TC    transport connection
TCA    terminal control area
TCAS    traffic alert collision avoidance system
TCP    transmission control protocol
TCP/IP    TCP/Internet protocol
TCS    tower communications system
TD    technical documentation
TDLS    tower data link services
TDM    time division multiplexer
TDMA    time division multiple access
TDST    tower data services terminal
TDWR    terminal Doppler weather radar
T&E    test and evaluation
TECOM    technical committee
TEI    text element identifiers
TELCO    telephone company
TERPS    terminal en route procedures
TERPS    terminal instrument procedures (FAA)
TES    trials end system (for ATN)
TFC    traffic
TFM    traffic flow management
TFR    temporary flight restriction
TFTP    trivial file transfer protocol
TG    transmission gate
TG4    maximum time between GSIF’s timer
TG5    maximum link overlap timer
TGT    target
TIA    Telecommunications Industry Association
TIP    tower integration program
TIS    traffic information service
TL    terminal location (ACARS/AFEPS)
TLS    target level of safety
T&M    time and materials
TM    timer-media access control
TM    technical manual
TMA    traffic management advisor
TMC    traffic management coordinator
TMC    test, monitor and control
TM&O    telecommunications management and operations
TMS-T    traffic management system transition
TMU    traffic management unit
TO    technical order
TOC    transfer of communications
TOR    terms of reference (ICAO/FAA)
TP    test point
TP4    transport protocol class 4
TPDU    transport protocol data unit
TPF    transaction processing facility
TPL    terminal permission list (ACARS/AFEPS)
TPM    technical performance management
TQM    total quality management
TRACON    terminal radar approach control
TRB    technical review board
TRD    transit routing domain
TRR    test readiness review
TS    time source
TS    transport service
TSA    technical services agreement
TSAP    transport service access point
TSC    term service commitment
TSC    transportation system center
TSDU    transport service data unit
TSG    technical subgroup
TSG    technical standards and guidelines
TSO    technical standard order (FAA)
TSP    transmitted signal power
TSS    technology support and services
TSTM    time source transition module
TT    test tools
TURB    turbulence
TVE    total vertical error
TWDL    two-way data link communications
TWIP    terminal weather information for pilots
TWP    technical work program
TX    transmit



UA    unnumbered acknowledgment
UART    universal asynchronous receiver transmitter
UAT    universal access transceiver
UATP    universal air travel plan
UAV    unmanned air vehicle
UBI    uplink block identifier
UCI    user computer interface
UD    user data
UDP    user datagram protocol
UHF    ultra-high frequency
UI    unnumbered information
UIR    upper information region
UL    uplink
ULWG    upper layer working group
UML    unified modeling language
UP    universal platform
UPRM    universal platform resource management
UPS    uninterruptible power supply
UPSMS    UPS management supply
URET    user request evaluation tool
URL    universal resource locator
USC    United States code
UTC    universal coordinated time
UTP    unshielded twisted pair
UUT    unit under test
UWB    ultra wide-band



V    volt
v8208    vdlM2 8208 protocol
VAC    volts alternating current
VANS    value-added network services
VAR    value-added reseller
VAP    value-added processor
VAS    value-added services
VC    virtual circuit
VCB    virtual circuit bridge
VCP    video cassette player
VCU    VDL control unit
VDC    volts direct current
VDD    version description document
VDL    VHF data link
VDLM2    VDL Mode 2
VDLM3    VDL Mode 3
VDLM4    VDL Mode 4
VDR    VHF data radio
VDU    visual display unit
VER    version
VFR    visual flight rules
VGA    video graphics adapter
VGS    VDLM2 ground station
VHF    very high frequency
VLSI    very large scale integration
VMC    visual meteorological conditions
VME    versa module Eurocard bus
VME    VHF management entity (VMEbus)
VMECC    versa module Eurocard card cage
VMON    VNMS health monitoring
VNAV    vertical navigation
VNMS    VDLM2 network management system
VOCRAD    voice radio
VOR    VHF omni-directional radio range
VPN    virtual private network
VRG    VDL reference guide
VSAT    very small aperture terminal
VSCS    voice switching and control system
VSD    VDL specific DTE address
VSM    vertical separation minimum
VSRS    voice switch replacement system
VSWR    voltage standing wave radio
VTAM    virtual telecommunications access method
VTOL    vertical takeoff and landing
VTS    vessel traffic system
V&V    verification and validation



WAAS    wide area augmentation system
WACS    wireless airport communication system
WADGPS    wide area differential GPS
WAFC    world area forecast center
WAN    wide area network
WARC    World Administrative Radio Conference
WARP    weather and radar processor
WASP    wireless access service point
WATRS    west Atlantic route structure
WBS    work breakdown structure
WC    waypoint capture
WG    working group
WJHTC    William J. Hughes Technical Center (FAA)
WGS    world geodetic system
WMO    World Meteorological Organization
WMSCR    weather message switching center replacement
WP    work procedure
WPR    waypoint position report
WPT    waypoint
WSDDM    weather support for deicing decision-making
WSR    weather surveillance radar
WWW    world wide Web
WX    weather
WXR    weather radar



X    cancel
XID    exchange identification
XFR    transfer
XMIT    transmit
XMTR    transmitter
XS    Societe Internationale de Telecommunications Aeronautiques (SITA)
XTI    X-open transport interface
XTP    express transfer protocol




Z    Zulu (Greenwich mean time)
ZFW    zero fuel weight
ZOC    zone of convergence
ZVF    zero velocity filter