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1 PPS : One Pulse Per Second
1 :1 : One-to-one relationship
1 :M : One-to-Many relationship
16PF : Sixteen Personality Factor Questionnaire
2D : Two Dimensional
3D : Three Dimensional

3D : Palair Macedonian (airline)
4D : Four Dimensional
4D FMS : 4D Flight Management System
4D-NAV : 4D Navigation
4DTN : 4D Trajectory Negotiation
4-MASt : 4-MAST group

5LNC : Five Letter Name Code
5-ST-RSG : 5-States Route Structure Group
5-STRSSG : 5-States Route Structure Steering Group
5-SRSWG : 5-States Route Structure Working Group
8.33 CP : 8.33 Contact Person
8.33 PMC : 8.33 Programme Management Cell
8.33 State : A State initially implementing 8.33 kHz channel spacing




A : Amber

A : Ampere

A : At or Above (constrained altitude)

A : Autotuned NAVAID
A : Austria

A SMGCS : Advanced Surface Movement Guidance and Control Systems

A/A : Air/Air
A/C, a/c : Aircraft
A/D : Analog-to-Digital
A/D Converter : Analogue-to Digital Converter
A/G : Air-Ground
A/I : Accident(s)/Incident(s)

A/l : Anti-ice
A/L : Auto Land 
A/P : Autopilot

A/T : Autothrottle

AA : American
AA : Approved agency

AAA: Advanced ATC System Amsterdam
AAA : Aesean Airliners Association

AAA : (or AAB, AAC...etc., in sequence) Amended meteorological message (message type designator)

AAATS : Australian Advanced Air Traffic Services  
AAC : Alpha Attenuation Coefficient

AAC : Aeronautical Administration Communication (a class of communication which supports administrative communication)

AAC : Airline Administrative Communication

AACC : Airport Associations Co-ordinating Council

AACE : Airfield Approach Control Element
AACI : Airports Association Council International
AACO : Arab Air Carriers Organisation

AAD : Assigned Altitude Deviation
AAF : ATM Added Functions
AAFCE : Allied Air Forces Central Europe
AAFG : ATM Added Functionality Sub-Group
AAG : AIS Automation Group 
AAGDI / AGADE : Automated Air/Ground Data Interchange
AAH : Autonomous Aircraft Hybrid

AAIB : Air Accident Investigation Branch (UK equivalent of NTSB)
AAIM : Aircraft Autonomous Integrity Monitoring

AAIS : Automated AIS

AAL : Above Aerodrome level
AALS : Advanced Approach and Landing System
AAM : Airbus Asset Management

AAM :  Airline Administration Message

AAME : Association of Aviation Medical Examiners
AAP : Advanced Automation Program

AAPA: Association of Asia Pacific Airlines

AAR : Airport Acceptance Rate or Airport Arrival Rate
AAR : Air-to-Air Refuelling

AAS : Advanced Automation System (the end systems for all FAA air traffic control, located at the ARTCCs

AASA : Air Lines Association of Southern Africa

AASC : Airport Authorities Steering Committee
AASI : Aeronautical Applications Service Interface
AASR : Airways and Airport Surveillance Radar
AAT : Alpha Attenuation Test

AATF : Airworthiness Assurance Task Force

AATMS : Advanced Air Traffic Management System

AATT : Advanced Aviation Transportation Technology
AAUI : Aeronautical Applications User Interface
AB : Action Button (mouse)
ABAS : Aircraft-based Augmentation System 
ABC : ATC Bypass Complex

ABET : Airspace Behavioural Engineering Technology 
ABFG : ATM Basic Functions Sub-Group
ABI : Advance Boundary Information

ABM : Abeam

ABN : Aerodrome Airport Beacon
ABPSK : Aviation Binary Phase Shift Keying

ABT : About

ABV : Above

AC : Air Canada
AC : Alternating Current

AC : Altocumulus
AC : Assessment Centre
AC : Assistant Controller
AC : Advisory Circular 
ACA : Air Traffic Centre Architecture 
ACA : Airport Co-ordinators Association
ACA : Airspace Control Activity
ACA : AUP / UUP Composition application (software)

ACA : Austrian Cockpit Association

ACAC : Arab Civil Aviation Council
Acad : Academic establishments
ACAD : Auto Computer Aided Design (Operator-Input + Display System)
ACAG : Airspace Co-ordination Agencies
ACAM : Airport Capacity Airside Modelling

ACAMS : Aircraft Condition Analysis and Management System
ACARS : Aircraft Communications, Addressing and Reporting System

ACARS ARINC communications and address reporting system (digital communications system used primarily for aircraft-to-airline messages)

ACARS MU ACARS Management Unit

ACAS : Airborne Collision Avoidance System
ACAS I : Aircraft Collision Avoidance System Version 1 
ACAS II : Aircraft Collision Avoidance System Version 2 
ACAS III : Aircraft Collision Avoidance System Version 3
ACASA : ACAS Analysis
ACATF : ATC Centre Communications Architecture Task Force

ACB : Aeroclub
ACC : Area Control Centre
ACC Controller : Area Controller
ACC Loop : Anticipation-Action-Comparison Loop 
ACCA : Air Charters Carriers Association

ACCC : Australian Competition and Consumer Commission
ACCEL : Accelerate
ACCESS : Aircraft Control Console for Experiments and Simulations Studies

ACCID : Notification of an aircraft accident
ACC-PC : ACC Planning Controller
ACCS : Air Command and Control System 
ACC-TC : ACC Tactical Controller

ACCUM : Accumulate

ACDAC : Asociacion Colombiana de Aviadores Civiles
ACDMD : Air Collaborative Decision Making Demonstrator
ACE : Allied Command Europe
ACE : Altimeter Control Equipment
ACE : ATC Communications Environment

ACF : Area Control Facility. See ACC or ARTC

ACFS : Advanced Concepts Flight Simulator (a generic "glass cockpit")
ACFT : Aircraft
ACG : Advanced ATS Concept Group
ACG : Advanced Concept Group  
ACG : ATN/CNS Consultation Group

ACG : ATS System Concept Working Group
ACG : Austro Control GmbH
ACH : ATC Flight Plan Change Message 
ACH : ATC Flight Plan Change 
ACI : Airports Council International
ACI : Area of Common Interest 
ACID : Aircraft Identification (ICAO)

ACIPLA : Asociacian Civil de Pilotos de Lineas Aereas (Uruquay)
ACK : Acknowledge(ment) message

ACL : Altimeter Check Location
ACL : ATC Clearances
ACM : Acceptance of (Radar) Co-ordination Message

ACM : Acceptable Means of Compliance
ACM : Airspace Control Measures
ACM : ATC Communication Management
ACMS : Aircraft Condition Monitoring System
ACN : Aircraft Classification Number
ACN : Airspace Co-ordination Notification
ACN : Austrian Communication Network

ACNZ : Airways Corporation of New Zealand
ACO : Airspace Co-ordination Order
ACOD : Area Conflict Detection
ACP : Accept Message
ACP : Acceptance Message
ACP : African, Caribbean and Pacific States
ACP : Aircraft Control Position (window)
ACP : Airspace Control Plan
ACP : Airspace Crossing Acceptance Message
ACP : Allied Communications Publication
ACP : Azimuth Change/Count Pulses
ACP : Area Control Procedural
ACPO : Aircraft Position Operator
ACPSC : Advisory Committee on Procurement and Sales Contracts (Eurocontrol/DF)

ACPT : Accept or Accepted

ACR : Air Carrier
ACR : Atlantic Co-ordinated Route

ACRPWG : Aircraft Crash Recovery Procedures Working Group

 ACS : Advanced Communication System 
ACS : Airspace Control System
ACS : Area Control Surveillance
ACSA : Allied Communications Security Agency
ACSE : Application Control Service Element

ACT : Active  
ACT : Activation message designator

ACT : ATC Activation message
ACT/LAM : Activation Message / Logical Acknowledgement Message
ACTF : Aeronautical Charting Task Force
ACU : Airspace / Antenna Control Unit. See BSU
AD : Administrative Domain  (ENOC)
AD : Aerodrome
AD : Air Defence
AD : Airworthiness Directive

AD : CFMU/FDOD - Airspace Data Section
ADA : Advisory Area
ADAGES : Action Plan Definition on the Basis of Architecture studies from GAAS for EATMS

ADAP : Automated Downlink of Airborne Parameters
ADAPT : ATS Data Acquisition, Processing and Transfer Panel (ICAO)
ADC : Air Defence Centre / Command
ADC : Air Data Computer
ADC : Analog to Digital Converter
ADCA : Air Defence Classification Area
ADCE : Aircraft Data Circuit-Terminating Equipment
ADCP : Air Defence Command Post
ADD : Architectural Design Document 
ADD : Average Delay per Delayed Flight
ADDI : Automated Digital Data Interchange (ICAO)

ADDN : Addition or Additional

ADDR : Address
ADE : Air Defence Element
ADE : Autonomous Display Equipment
ADEG : ATS Data Exchange Group
ADEP : Aerodrome of Departure
ADES : Aerodrome of Destination
ADEXA : Air Defence Exercise Area
ADEXP : ATS Data Exchange Presentation (message format used for IFPS) ; ATS Data Exchange Program Format

ADF : Automatic Direction Finder
ADFL : Augmented Dynamic Flight Leg

ADIRS : Air Data Inertial Reference System
ADGE : Air Defence Ground Environment

ADJ : Adjacent
ADI : Aerodrome Control Instrument

ADI : Attitude Director lndicator
ADI : Attitude Display Indicator
ADIDS : Advanced Data & Image Distribution System (CCTV Application)
ADIRS : Air Data Inertial Reference System

ADIRU : Air Data Inertial Reference Unit

ADIS : Automatic dependent surveillance and Data Link Interim System

ADIS : Automatic dependent surveillance and Data Link Interim System
ADIS (P) : Automated Data Interchange System (Panel) - ICAO
ADIZ : Air Defence Identification Zone
ADLP : Aircraft Data Link Processor (the Mode S subnetwork function onboard the aircraft that implements the OSI network layer protocols)
ADM : Administrative / Administration

ADM : Aeronautical Decision Making
ADM : Average Delay per Movement
ADM : Airborne Data Bus

ADM : Air Data Module

ADMA : Aviation Distributors and Manufactureres Association
ADMD : Airspace Data Management & Distribution
ADNC : Air Defence Notification Centre (GR)
ADNS : Aeronautical Radio Incorporated Data Network Service
ADOC : Air Defence Operations Centre
ADOLT : Air Defence Liaison Team
ADORA : Analysis and Definition of the Operational Requirements for ATM
ADP : Activity Predictor Display

ADP : ATFM Daily Plan
ADP : Automated Data Processing or Auxiliary Data Processing
ADPG : ATM Data Processing Sub-Group
ADR : Advisory Route
ADR : Air Data Reference
ADR : Airfield Damage Repair
ADR : Average Delay per Regulated Flight
ADREP : Accident/Incident Reporting System
ADRS : Air Defence Radar Site

ADS : Air Data System
ADS : Automatic Dependent Surveillance
ADS-A : Automatic Dependent Surveillance-Addressed
ADS-B : Automatic Dependent Surveillance-Broadcast
ADS-C : Automatic Dependent Surveillance-Contract
ADS-P : Automatic Dependent Surveillance-Panel (ICAO)
ADS-R : Automatic Dependent Surveillance-Report
ADSEL : Address Selective SSR System (UK)
ADSIA : Allied Data Systems Interoperability Agency
ADSP : ADS Processor

ADSP : Automatic Dependent Surveillance Panel (ICAO)

ADT : Air Data Tester
ADT : Approved Departure Time
ADTI : Additional Technical Information (ODS - ESCO)
ADUG : Airport Database User Group
ADV : Aerodrome Control Visual
ADVON : Advanced Echelon

ADZ : Advise

ADZD : Advised

ADZY : Advisory
AE : ATM Engineering
AE : Application Entity

AE : United  Arab Emirates (ISO Country Code)
AEA : Association of European Airlines

AECB : Atomic Energy Control Board
AECG : ACAS Evaluation and Co-ordination Group

AFCS Automatic Flight Control System
AEEC : Airlines Electronic Engineering Committee
AEFMP : Algeria, Spain, France, Maroc, Portugal Project
AEGIS : Airborne Early Warning Ground Environment Integrated Segment
AEGIS : ATM European Group for Improvement of Scenarios
AEG-TFK : AEG-Telefunken

AEM : Airports & Environment Management (Eurocontrol)
AENA : Aeropuertos Españoles y Navegatión Aérea (ES) / Spanish Airport and Air navigation Administration
AERA : Automated En-Route Air Traffic Control
AEREA : Association of European Research Establishments in Aeronautics

AEROSAT : Aeronautical Satellite Council

AES : Aircraft / Airborne Earth Station (ICAO - ADS)
AES : ATC Engineering Section
AES : Automatic Enhanced Surveillance
AEV : Annual Equivalent Value
AEW : Airborne Early Warning
AEWPD : Adapted EATM Work Programme Document
AF : Air Force

AF : Air France (airline)
AF : Audio Frequency (VCS)
AF : DME Arc to a Fix (ARINC 424 Path Terminator)

AFA : Association of Flight Attendants
AFAS : Aircraft in the Future ATM System
AFAST : Active Final Approach Spacing Tool
AFB : Air Force Base
AFC : Airport Facilities Control (ICAO)
AFC : ATC Frequency Change (service)

AFCAC : African Civil Aviation Commission
AFCNF : Air Force Central NOTAM Facility 
AFCS : Automatic Flight Control System

AFD : Airport Facility Directory
AFD : Associated Flight Details

AFDS : Autopilot Flight Director System (also A/P F/D)
AFFSC (E) : Air Forces Flight Safety Committee (Europe)
AFG : Advisory Financial Group (ex-FCG/Eurocontrol)

AFI : Africa-Indian Ocean Region (ICAO)
AFIL : Air Filed Flight Plan  
AFIS : Airport/Aerodrome Flight Information Service
AFISO : Aerodrome Flight information Service Officer

AFIZ : Aerodrome Flight information Zone
AFL : Actual Flight Level
AFL : Assigned Flight Level

AFM : Yes or Affirm or Affirmative or That is Correct

AFM : Airplane Flight Manual
AFMS : Advanced Flight Management System
AFMSG : Audit and Financial Matters Sub-Group
AFN : Air Traffic Services Facilities Notification

AFN: Airspace / Flow Management & Navigation Business Division (Eurocontrol)
AFP : Active Flight Plan Processing

AFP : Area Forecast Panel
AFP : ATC Flight Plan Proposal
AFPA : Automated Flight Plan to Track Association
AFPL : ADEXP Filed Flight Plan

AFRAA : African Airlines Association
AFS : Advanced Functional Simulator
AFS : Aeronautical Fixed Services

AFS : Automatic Flight System
AFSATCOM : Airborne Satellite Communication

AFT : After (time or place)

AFTN : Aeronautical Fixed Telecommunication Network

AFW : Area Flows Window

AFWA : Automatic Flight Weather Advisory
AGA : Aerodromes and Ground Aids
AGARD : Advisory Group on Aeronautical Research and Developments

AGAS : European Action Group for ATM Safety

AGATE :Advanced General Aviation Transport Experiments  
AGC : Automatic Gain Control (VCS)
AGCS : Air-Ground Communication System
AGCSG : Air/Ground Communication Sub-Group Meeting
AGDC : Air/Ground Data Communications
AGDC-SG : Air/Ground Data Communications Sub Group. See AGSG
AGDC-TF : Air/Ground Data Communications-TF (ODT)
AGDL : Air-Ground Data Link
AGDLS : Air-Ground Data Link System
AGL : Above Ground Level
AGLAE : Air-Ground Data Link Applications Experimentation

AGN : Again
AGN : Agenda
AGOD : Advisory Group on Deliverables
AGR : Agreement
AGSG : Air / Ground Data Communication Sub group
AGVC-SG : Air/Ground Voice Communication Sub Group
AHDG : Assigned Heading
AHEAD : Automation and Harmonisation of European Aeronautical Data
AHGSO : Ad Hoc Group of Senior Officials
AHMI : Airborne Human Machine Interface
AHRS : Attitude and Heading Reference System

AHS : American Helicopter Association
AI : Artificial Intelligence

AI : Air India (airline)

AIA : Aerospace Industries Association

AIAA : American Institute of Aeronautics and Astronautics

AIAA : Area of Intense Aerial Activity
AIB : Aeronautical Information Bulletin (EAD)
AIC : Aeronautical Information Circular
AICB : Air Initiated Comm-B Protocol
AICG : Ab Initio Co-ordination Group
AICG : ACAS Implementation Co-ordination Group
AICG : Airport Interface Co-ordination Group
AICM : Aeronautical Information Conceptual Model (EAD)
AID : Aid or Aircraft Identification
AIDA : Aeronautical Information and Data handling Austria
AIDC : ATS Interfacility Data Communications (ICAO)
AIDS : Aircraft Integrated Data System
AIG : ACAS Implementation Group ; Automatic Input Generation
AIG : Accident Investigation and Prevention
AIL : Aeronautical Item Location Bank

AIM : Airman’s Information Manual
AIM : ATFM Information Message  
AIM-FANS : Airbus Interoperable Modular FANS

AIMS : Airplane Information Management System (Boeing 777)
AIMS : Aircraft Integrated Monitoring (Information Management) System
AIP : Aeronautical Information Publication
AIPN : Appointing authority
AIR : Armament Initiative and Requirements
AIR 4653 : Aerospace Information Report 4653 - (Flight Management Systems Review)
AIR : Air Control
AIRAC : Aeronautical Information Regulation and Control
AIRCOM : Aircraft Communications
AIREP : Air-Report (ICAO)
AIRMET : Air Meteorological Information Report which may affect the safety of low-level aircraft operations
AIRPROX : The code word used in air traffic incident report to designate aircraft proximity (ICAO)

AIRS : Advanced Infrared Sounder
AIS : Aeronautical Information Services
AISAP : AIS Automation Specialist Panel
AISAS : Aeronautical Information Services Automated System
AISC : Aeronautical Mobile Communications System Panel
AISC : Aeronautical Industry Service Communication
AISG : AIS Automation Group
AISPOP : AIS Planning and Operations Subgroup
AISS : Aeronautical Information Server System 
AIS-TF : AIS Training Task Force
AISU : Aeronautical Information Service Unit
AITSC : Administrative IT Steering Committee
AIXM : Aeronautical Information Exchange Model
AKARD : Available Knowledge And required system Research and Development
AL : Aircraft Label
AL : Albania (ISO Country Code)
AL : Alerting Service

AL : Allegheny

ALA : Alighting Area
ALB : Alternative Label
ALCC : Airlift Central Co-ordination Centre
ALCE : Airlift Control Element
ALCM : Air Launched Cruise Missile
ALD : Airlift Division

ALERFA : Alert Phase
Alert : Alert phase

Alert Indicator : (visual or auditory) which provides information to the flightcrew in a timely manner about an event requiring pilot awareness.
ALIM : Altitude Limit (Positive RA Altitude Threshold)
ALLA : Allied Long Lines Agency
ALMC : Airlift Movement Cell
ALO : Air Force Liaison Officer

ALPA : Air Line Pilots Association

ALR : Alerting message

ALRS : Alerting Service
ALRT : Alert

ALS : Approach Lighting System
ALS : Architecture Layer Structure (ISO)
ALS : Automatic Line Switch (RMCDE)
ALS : Automatizovany Letisni System (CZ) / Automated Airport System

ALSTG : Altimeter Setting
ALT : Airborne Link Terminal

ALT :  Altitude

ALT : Alternate

ALTM : Altimerer

ALTN : Alternate Aerodrome

ALTNLY : Alternately

ALT HOLD : Altitude Hold Mode
ALTRV : Altitude Reservation System

AM : Aeromexico
AM : Airspace Management
AM : Amplitude Modulation
AM : Armenia (ISO Country Code)
AM : Arrival Manager
AM : Attribute Modification

AMA : Area Minimum Altitude
AMA : Airlift Management Agency
AMAN : Arrival Manager (APATSI)
AMC : Airspace Management Cell
AMC : ATC Microphone Check (service)

AMC : Avionics Maintenance Conference
AMC/CADF : Airspace Management Cell - ECAC Centralised Airspace Data Function
AMCP : Aeronautical Mobile Communication Panel (ICAO)
AMD : Administrative Management Domain

AMD : Advisory Map Display

AMD : Amend or Amended
AMD : Arrival manager Display
AMDP : Airspace Management Data Processing
AMDP-TF : EATCHIP Airspace Management Data Processing Task Force
AMDT : Amendment (ICAO)
AMDWP : Aeromedical Working Party
AME : ATM Message Exchange
AMEG : Air Miss Evaluation Group

AMGR : Airport Manager
AMHS : Aeronautical Message Handling Service

AMI : Airline Modifiable Information
AMI : Administrative and Management Information Software
AMID : Approach Multi-Input Device (ODID)
AMJ : Advisory Material Joint

AMLCD : Active Matrix Liquid Crystal Display
AML (WP) : Airfield Markings and Lighting (Working Party)
AMN : Airspace Management and Navigation (EATM Unit)
AMOC : ATFM Air Traffic Flow Management
AMOC : ATFM Modelling Capability

AMOS : Automatic Meteorological Observing System
AMOS : ARTAS Maintenance and Operational Support organisation

AMOSS : Airline Maintenance and Operation Support System
AMPS : American Mobile Phone System
AMS : Aeronautical Mobile Service
AMS : Airspace Management Service
AMS : ATC Model-Simulations Studies
AMS(R)S : Aeronautical Mobile Satellite (Route) Service  
AMSC : Allied Military Security Code
AMSL : Above Mean Sea Level
AMSS : Aeronautical Mobile Satellite Services
AMSS : Aeronautical Mobile Satellite System
AMSS : Automatic Message Switching System
AMSSP : Aeronautical Mobile Satellite Service Panel
AMT : ADS Mediterranean Trials
AMTI : Adaptive Moving Target Indicator
AN : Access Node (RMCDE)
ANA : Aeroportos e Navegaçao Aérea (PT)

ANA All Nippon Airways
ANA-EP : Aeroportos e Navegaçao Aérea Empresa Pública (PT)
ANC : Access Network Computer
ANC : Air Navigation Commission / Conference (ICAO)
ANCAT : Abatement of Nuisances Caused by Air Transport (ECAC environmental policy committee (ENV : AL)
ANDRA : Advanced Node for Data Relay in ATN
ANDS : ANS Department
ANERC : Advanced New En-Route Centre (UK)
ANM : ATFM Notification Message (CFMU / ECAC States)
ANOVA : Analysis of Variance

ANP : Actual Navigation Performance
ANP : Air Navigation Plan
ANPP : Air Navigation Plan Publication
ANS : Air Navigation Service

ANS : Answer
ANS/CR : Air Navigation Services of the Czech Republic
ANSA : International Advisory Group Air Navigation Services
ANSEP : Air Navigation Services Economics Panel (ICAO)

ANSI : American National Standards Institute

ANSIR : Advanced Navigation System Inertial Reference
ANSO : Air Navigation Services Offices (Irish aviation authority)
ANSP : Air Navigation Service Provider
ANT : Airspace and Navigation Team
AO : Aircraft Operator 
AO : Airlines Operator
AO : Arrival Operations
AO : ATM Operations
AOA : Aircraft Operating Agency (e.g. Airlines)

AOA : Angle-of-Attack

AOA : Airport Operations Area
AOB : Air Order of Battle
AOB : Angle of Bank
AOC : Advanced Operational Capability

AOC : Aerodrome Obstuction/Obstacle Chart
AOC : Aeronautical Operational Communications
AOC : Aircraft Operating Company
AOC : Aircraft Operations Centre (ICAO)
AOC : Airline Operation Control

AOC Aeronautical Operation Control (communications which support safety and regularity of flight that normally take place between aircraft and the operator)
AOC : Assume of Control (ODID)
AOC : Auxiliary Output Chip
AOC : Aeronautical Operational Control
AOC : Air Operator's Certificate

AOC : Airline Operational Communications

AOCC : Aircraft Operator Control Centre
AOCI : Airport Operators Council International
AOCP : Airborne Operational Computer Programme

AOCS Attitude and Orbit Control System

AOCU : Aircraft Operator Contol Unit

AOF : AIS Office (EAD)
AOF : Allocation of Functions

AOG : Aircraft On Ground
AOI : Aircraft Operations Information
AOI : Area of Operational Interest
AOI : AIS Office
AOIS : Aeronautical Operational Information System
AOM : Aircraft Operations Manual
AOP : Aeronautical OSI Profile
AOPA : Aircraft Owner and Pilot Associations
AOPG : Aerodrome Operations Group (ICAO)
AOPTF : Aerodrome Operations Task Force
AOR : Area of Responsibility
AOR : Atlantic Ocean Region (ICAO)
AOR-E : Atlantic Ocean Region - East (ICAO)
AORTF : ATM Added Functionality Operational Requirements Task Force
AOR-W : Atlantic Ocean Region - West (ICAO)
AOS : Airport Operations Strategy Drafting Group
AOT : Airport Operations Team
AOU : Aircraft Operator Unit 
AOWIR : Aircraft Operator What-If Re-routing
AOWP : Airport Operations Work Plan

AP : Airport
AP : Auto-Pilot
AP : Application Process

APA Allied Pilots Association
APANPIRG : Asia/Pacific Air Navigation Planning and Implementation Regional Group
APAPI : Abbreviated Precision Approach Path Indicator
APATSI : Airport / Air Traffic Systems Interface (ECAC)
APB : APATSI Project Board
APC : Aeronautical Passenger Communications / Correspondence
APC : Aeronautical Public Correspondence
APC : Assistant Planning Controller

APCH : Approach
APD : Activity Predictor Display
APDLC : Aircraft Proximity Data Link Communication (ICAO)
APDSG : ATM Procedures Development Sub-Group
APE : Analysis Programme for Evaluation
API : Application Programming Interface 
APIRG : Africa-Indian Ocean Planning and Implementation Regional Group (ICAO)
APL : Abbreviated Flight Plan 
APL : Applied Physics Laboratory
APL : ATC Flight Plan

APLGT : Airport Lighting
APM : Architecture Project Management
APMB : ACAS Programme Management Board

APMS Automated Performance Measurement System
APO : Airport Operator
APO : Aircraft Performance and Operations
APOD : Airport of Debarkation
APP : Approach Centre / Control (office/service)
APP controller/director : Approach controller/director
App. : Appendix
APPA-SG : ATFM Policies and Principles Advisory Sub-Group
APP-ASS : Approach-Assistant

APPR : Approach/Approach Mode

APR : Automatic Position Reporting

APRT : Airport

APRX : Approximate or Approximately

APS : Approach Control Surveillance
APSG : ACAS Programme Steering Group

APSG : After Passing
APT : Airport(s)
APT : Airspace Planning Team  became ANT (March 94)
APU : Auxiliary Power Unit

APV : Approve or Approved or Approval
APW : Area Proximity Warning
AQAP : Allied Quality Assurance Publication
AQG : Agency Quality Group
AQP : Advanced Qualification Programme
A-QPSK : Aviation Quadrature Phase Shift Keying
AR : Agency Representative (CIP)
AR : Air Route
AR : Automatic Reminder

AR : Argentina (ISO Country Code)
AR-1 : Approach Radar 1

ARAC Aviation Rulemaking Advisory Committee
ARB : Authoritative Representative Body
ARC 2000 : Automatic Radar Control for the 21st Century (CEE)
ARC : Airlift Requirement Centre
arc : assigned rate of climb/descent
ARC : Advanced Research for/in Air Traffic Control

ARC (ARCH) : CFMU – Archive System
ARCC : Air Rescue Co-ordination Centre
ARCH : Archives and Quality Control System 
ARCID : Aircraft Identification 
ARCOS : Arrival Co-ordination System 
ARCP : Air Refuelling Control Point
ARDEP : Analysis / Assessment of Research and Development in Eurocontrol Programmes
ARDRS : Automatic Radar Data Recording System
ARDS : ATM Architecture and overall system engineering
ARETA : ATM with RNAV in Extended Terminal Area
ARFA : Allied Radio Frequency Agency

ARFF : Airport Rescue and Fire Fighting

ARFOR : Area Forecast
ARH : Architecture
ARIBA : ATM system safety criticality Raised Issues in Balancing Actors Responsibility
ARINC : Aeronautical Radio Incorporated (a nonprofit corporation owned by member airlines to define form, fit and functions of avionics equipment)
ARINC 306 : Guidance For Designers Of Aircraft- Electronic Installations
ARINC 307 : Aircraft Integrated Data System Wire Bundle Provisions
ARINC 404A : Air Transport Equipment Cases And Racking
ARINC 406A : Airborne Electronic Equipment
ARINC 408A : Air Transport Indicator Cases And Mounting
ARINC 413A : Guidance For Aircraft Power Utilisation And Transient Protection
ARINC 414 : General Guidance For Equipment And Installation Engineers
ARINC 415 : Operation/Technical Guidelines On Failure Warning and Functional Test
ARINC 419 : Digital Data System Compendium
ARINC 421 : Guidance For Standard Subdivision of ATA Spec 100 Numbering System for Avionics
ARINC 422 : Guidance For Modification Status Indicators & Avionics Service Bulletins
ARINC 424 : Navigation System Data Base
ARINC 429 : Mark 33 Digital Information Transfer System
ARINC 528 : Airborne Tape Recorder
ARINC 533A : Airborne HF SSB/AM System
ARINC 541 : Airborne Magnetic Flight Data Recorder
ARINC 542 : Airborne Oscillograph Flight Data Recorder
ARINC 542A : Digital Flight Data Recorder
ARINC 551 : Airborne Glide Slope Receiver - Mark 2
ARINC 557 : Airborne Voice Recorder
ARINC 559A : Mark 2 Airborne HF SSB/AM System
ARINC 561 : Air Transport Inertial Navigation System - INS
ARINC 566 : Airborne VHF Communications Transceiver And Mark 1 VHF SATCOM System
ARINC 566A : Mark 3 VHF Communications Transceiver
ARINC 569 : Airborne Distance Measuring Equipment
ARINC 569 : Heading and Altitude Sensor (HAS)
ARINC 571 : Inertial Reference System (INS)
ARINC 572 : Mark 2 Air Traffic Control Transponder
ARINC 573 : Aircraft Integrated Data System (AIDS) Mark 2
ARINC 574 : Passenger Announcement, Entertainment & Service Multiplex System
ARINC 575 : Mark 3 Subsonic Air Data System (Digital)
ARINC 576 : Mark 4 Subsonic Air Data System
ARINC 577 : Audible Warning System
ARINC 578 : Airborne ILS Receiver
ARINC 579 : Airborne VOR Receiver
ARINC 585 : Electronic Chronometer System
ARINC 591 : Quick Access Recorder For Aids System (OAR)
ARINC 592 : Airborne Passenger Tape Record
ARINC 594 : Ground Proximity Warning System (GPWS)
ARINC 595 : Barometric Altitude Rate Computer
ARINC 596 : Mark 2 Airborne SELCAL System
ARINC 597 : Aircraft Communications Addressing And Reporting System (ACARS)
ARINC 597A : Enhanced ACARS Avionics
ARINC 59MA : Airborne Announcement Tape Reproducer
ARINC 600 : Air Transport Avionics Equipment Interfaces
ARINC 601 : Control/Display Interfaces
ARINC 602 : Test Equipment Guidance
ARINC 602A : Test Equipment Guidance
ARINC 603 : Airborne Computer Data Loader
ARINC 604 : Guidance For Design And Use Of built-In Test Equipment (BITE)
ARINC 605 : Users Guide For ARINC 616 Avionics Subset Of ATLAS Language
ARINC 606 : Guidance For Electrostatic Sensitive Device Utilisation & Protection, Sup. 1
ARINC 608 : Standard Modular Avionics Repair And Test System (SMART)
ARINC 609 : Design Guidance For Aircraft Electrical Power Systems
ARINC 610 : Guidance For Design and Integration of Aircraft Avionics Equipment In Simulators, Supplement 1
ARINC 611 : Guidance For The Design and Installation Of Fuel Quantity Systems, Sup. 1
ARINC 612 : BITE Glossary
ARINC 613 : Guidance for Using the Ada Programming Language in Avionics Systems
ARINC 614 : Standard Firmware Loader For Avionics Shops
ARINC 615 : Airborne Computer High Speed Data Loader, Supplement 3
ARINC 616 : Avionics Subset of ATLAS Language
ARINC 620 : Data Link Ground System Standard And Interface Specification

ARINC 622-1 : The ACARS Convergence Process
ARINC 624 : Design Guidance For Onboard Maintenance System
ARINC 626 : Standard ATLAS For Modular Test
ARINC 627 : Programmers Guide For Smart Systems Using ARINC 626 ATLAS
ARINC 629 : Multi Tester Data Bus : Part 1 - Technical Description
ARINC 629 : Multi-Transmitter Data Bus
ARINC 631 : Aviation Packet Communications Functional Description
ARINC 651 : Design Guidance For Integrated Modular Electronics
ARINC 659 : Backplane Data Bus for Integrated Modular Avionics
ARINC 701 : Flight Control Computer System
ARINC 702 : Flight Management Computer, Supplement 4 & 5
ARINC 703 : Thrust Control Computer
ARINC 704 : Inertial Reference System, Supplement 6
ARINC 705 : Altitude and Heading Reference System (AHRS)
ARINC 706 : Subsonic Air Data System
ARINC 707 : Radio Altimeter, Supplement 6
ARINC 708 : Airborne Weather Radar
ARINC 709 : Airborne Distance Measuring Equipment, Supplement 8
ARINC 709A : Precision Airborne Distance Measuring Equipment
ARINC 710  : Mark 2 Airborne ILS Receiver
ARINC 711 : Mark 2 Airborne VOR Receiver
ARINC 714 : Mark 3 Airborne SELCAL Systems
ARINC 715 : Airborne Passenger Address Amplifier
ARINC 716 : Airborne VHF Communications Transceiver
ARINC 717 : Flight Data Acquisition And Recording System
ARINC 718 : Mark 3 ATC Transponder
ARINC 719 : Airborne HF/SSB System
ARINC 720 : Digital Frequency/Function Selection for Airborne
ARINC 722 : Electronic Equipment Protection Video System
ARINC 723 : Ground Proximity Warning System (GPWS)
ARINC 724 : Mark 2 Aircraft Communications
ARINC 724A : Mark 2 ACARS Avionics
ARINC 724B : Aircraft Communications Addressing and Reporting System (ACARS)
ARINC 725 : Electronic Flight Instruments (EFIS)
ARINC 726 : Flight Warning Computer System
ARINC 727 : Airborne Microwave Landing System
ARINC 728 : Avionics Refrigeration and Cooling System (ARCS)
ARINC 729 : Analog And Discrete Data Converter System
ARINC 730 : Airborne Separator Assurance System
ARINC 731 : Electronic Chronometer
ARINC 732 : Mark 2 Airborne Passenger Audio Entertainment Tape Reproducer, Supplement 1
ARINC 735 : Traffic Alert and Collision Avoidance System (TCAS), Supplement 1
ARINC 737 : On Board Weight and Balance System. Supplement 1
ARINC 738 : Air Data and Inertial Reference System (ADIRS)
ARINC 739 : Multi-Purpose Control and Display Unit
ARINC 740 : Multiple-Input Cockpit Printer
ARINC 7411P2 : Aviation Satellite Communication System : Part 2 - Satellite Design
ARINC 741P1 : Aviation Satellite Communication System : Part I- Aircraft Installation Provisions
ARINC 741P4 : Aviation Satellite Communications System : Part 4 - Specification and Description Language
ARINC 742 : Design Guidance For Windshear Warning and Guidance Equipment
ARINC 743 : Airborne Global Positioning System Receiver
ARINC 744 : Full Format Printer
ARINC 745 : Automatic Dependent Surveillance, Supplement 1
ARINC 746 : Cabin Communications System, Supplement 1
ARINC 747 : Flight Data Recorder
ARINC 748 : Communications Management Unit (CMU)
ARINC 750 : VHF Data Radio (VDR)
ARINC 751 : Gate-Aircraft Terminal Environment Link (Gatelink) - Aircraft Side
ARINC 752 : TFTS Airborne Radio Sub-System
ARINC 753 : HF Data Link System
ARINC 757 : Cockpit Voice Recorder (CVR)
ARINC539A : Airborne 400 Hz AC Tape Reproducer
ARLO : Air Liaison Officer
ARM : ADS Report Message
ARM : Air Request Message
ARM : Anti Radiation Missile
ARM : Armenia
ARMATS : State Closed Joint-Stock Company of Armenian Air Traffic Services
ARN : ATS Routes and Associated Navigation Means
ARN-1 (Table) : Basic ATS Route Network in the Lower and Upper Airspace
ARN-2 (Table) : Radio Navigation Aids Associated with the Basic ATS Route Network Terminal Area and Instrument Approach Procedures
ARN-V2 : ATS Route Network - Version 2 (ECAC, EATM)
ARN-V3 : ATS Route Network - Version 3 (ECAC, EATM)

ARNG : Arrange
ARO : Air Traffic Service Reporting Office
ARP : Aerodrome Reference Point

ARP :  Aerospace Recommended Practice
ARP : Automated Route Planning
ARPA : Advanced Research Project Agency

ARPL : ADEXP Format Repetitive Flight Plans Message

ARQ : Automatic error Correction
ARQ : Automatic Request Repeat

ARQ : Automatic Response to Query
ARR : Arrive or Arrival or Arrival Message
ARR SP : Arrival Sequence Planner
ARS : Aeronautical Radio Navigation Service
ARS : Avoidance Routing Scheme

ARS : Special air-report (message type designator)

ARSA : Airport Radar Serve Area
ARSC : Air Rescue Sub Centre
ARSR : Air Route Surveillance Radar

ARST :Arresting (specify (part of) aircraft arresting equipment)
ART : Analysis and Replay Tool
ARTAS : Air Traffic Management Surveillance Tracker and Server System
ARTCC : Air Route Traffic Control Centre
Artemis : An ESA experimental telecommunications satellite hosting an EGNOS navigation transponder
ARTES-9 : Advanced Research in Telecommunication Systems
ARTS : Area Radar Training Squadron 
ARTS : Automated Radar Terminal System

ARU : Archive to UNIX
ARU : Airspace Reservation Unit
AS : Airspeed
AS : Airspace

AS : Altostratus
AS, A-S : Anti-Spoofing
ASA : Aircraft Situation Awareness
ASA : Automated Support to ATC
ASA : Automatic Slot Assignment
ASA System : Automatic Slot Assignment System
ASAP : Aircraft Separation Assurance Programme
ASAP : As soon as possible / practicable
ASARS : Air Surveillance Airborne Radar System
ASAS : Airborne Separation Assurance System
ASC : Ascend to or Ascending to
ASCAP : Automatic SSR Code Assignment Procedure
ASCB : Avionics Standard Communication Bus
ASCII : American Standard Code for Information Interchange / Exchange
ASCOT : Airport Slots Compliance Tools
ASDA : Accelerated Stop Distance Available
ASDAR : Aircraft to Satellite Data Relay

ASD : CFMU/ENGD - Architecture & System Design Section
ASDE : Airport Surface Detection Equipment
ASD-TF : Air Situation Display Task Force
ASE : Altimetry System Error
ASE : Application Service Element
ASECNA : Agency for the Safety of Air Navigation in Africa and Madagascar
ASEP : ACCS Surveillance Exploratory Prototype (NATO / SHAPE)
ASHTAM : NOTAM relating to volcanic and/or dust activity (ICAO)
ASI : Aerospace Sciences Inc.
ASI : Asia Region (ICAO)

ASI Air Speed Indicator

ASIC : Application-Specific Integrated Circuit
ASM : Ad-hoc Schedule Message
ASM : AirSpace Management
ASMAC : Automated System for Management of Aeronautical Information and Charting
ASMC : Airspace Management Communications
ASMGCS : Advanced Surface Movement Guidance and Control Systems
ASMI : Airport Surface Movement Indicator
ASMT : ATM Safety Monitoring Tool

ASMTF : Airspace Management Task Force
ASN : Abstract Syntax Notation
ASN 1 : Abstract Syntax Notation One
ASNO : Approach Sequence Number
ASO : Air Surveillance Officer
ASOC : Air Sovereignty Operations Centre
ASOC : Army Support Operations Centre
ASOP : Airspace Organisation and Procedures

ASOS : Automatic Surface Observing System
ASP : Adjustable System Parameter 
ASP : Aeronautical Fixed Service Systems Planning for Data Interchange Panel
ASP : Air Space
ASP : AIRCOM Service Processor (SITA)
ASP : Arrival Sequence Planner
asp : assigned speed

ASPH : Asphalt
ASPP : Aeronautical Fixed Service Systems Planning for Data Interchange Panel
ASQF : Application Specific Qualification Facility (part of EGNOS)
ASR : Airport Surveillance Radar (TAR)

ASR : Altimeter Setting Region
ASRS : Aviation Safety Reporting System
ASRT : Air Support Radar Team
ASSR : Assigned SSR code (FPPS/DECADE)
ASTA : Airport Surface Traffic Automation
ASTER : Aviation Safety Targets for Effective Regulation
ASTERIX : All-purpose Structured Eurocontrol Radar Information Exchange.
ASTP : ADS Studies and Trials Project
ASW : Anti Submarine Warfare
ASW : Air Situation Window

AT At (an altitude)
AT : Actual Time Count Down
AT : Air Transport
AT : At Time

AT…: At (following by time at which weather change is foecast to occur)
AT : Austria (ISO Country Code)

AT : Royal Air Maroc (airline)
ATA : Actual Time of Arrival
ATA : Air Transport Association (of America)
ATAC : Airspace Traffic Data Capture
ATAF : Allied Tactical Air Force

ATAFF : Air Traffic Arbitrated Free Flight
ATAG : Air Transport Action Group
ATAR : Automatic Air Reporting
ATARS : Automatic Traffic Avoidance and Resolution System
ATAS : Air Traffic Advisory Service
ATC : Air Traffic Control

ATCA : Air Traffic Control Association (US)
ATCA : Allied Tactical Communications Agency
ATCA : Air Traffic Control Assistant
ATCAP : Air Traffic Control Automation Panel (ICAO)
ATCAS : (Sweden) ATC Automated System
ATCC : Air Traffic Control Centre
ATCC : Air Traffic Control Clearance

ATCCC : Air Traffic Contol Command Centre
ATCEUC : Air Traffic Controllers European Unions Co-ordination
ATCgram : Illustration in graph form of the main functional levels of ATC systems
ATC-HMI : Air Traffic Control Human Machine Interface
ATCI : Airport ATC and Information systems
ATCO : Air Traffic Controller or Air Traffic Control Officer

ATCRBS : Air Traffic Control Radar Beacon System
ATCRU : Air Traffic Control Radar Unit
ATCS : Air Traffic Control Service

ATCS Advanced Train Control Systems

ATCSCC Air Traffic Control System Command Center

ATCSQ : ATC Safety Questionnaire

ATCT : Airport Traffic Control Tower
ATCU : Air Traffic Control Unit
ATD : Actual Time of Departure
ATD : Along Track Distance
ATDS : Airborne Tactical Data System
ATE : Automatic Test Equipment
ATFC : Air Traffic Flow Controller
ATFM : Air Traffic Flow Management

ATFM : CFMU/DEVD - ATFM Application Section
ATFMC : Air Traffic Flow Management Communications
ATFMO : Air Traffic Flow Management Organisation
ATFMP : Air Traffic Flow Management Position 
ATFMS : Air Traffic Flow Management System
ATFMU : Air Traffic Flow Management Unit
ATFR : Air Traffic Flow Regulator
ATG : Air Traffic Generator

ATHR Autothrust System

ATI : Automatic Tracking Initiation
ATIC : Administrative and Technical Inspection Committee (Agency structure)

ATIF : ATN Trials Infrastructure
ATILO : Administrative Tribunal of the International Labour Organisation

ATIS : Automatic Terminal Information Service
ATLAS : Air Traffic Land and Air Study [or Airborne Systems] (European Commission)

Atm : Tyre Pressure (KG/cm3)
ATM : Air Traffic Management

ATM : Air Transportation Management
ATM : Asynchronous Transfer Mode
ATM 2000+ : Eurocontrol ATM Strategy for the Years 2000+
ATMAS : Air Traffic Management Automated System (It. ATFM)
ATMC : Air Traffic Management Centre
ATMCP : ATM Operational Concept Panel (ICAO)
ATMCT : Air Terminal Movement Control Team Centre (NATS UK)
ATMG : Air Traffic Management Group
ATMO : Air Traffic Management Organisation
ATMOS : Air Traffic Management Operating System
ATMS : Advanced Air Traffic Management System
ATN Aeronautical Telecommunications Network (the collection of ground subnetworks, air/ground subnetworks and airborne subnetworks interconnected by ATN routers that support computer-to-computer, internetwork communication and message transfer between host computers using the OSI ISO protocol architecture)

ATN RD : Aeronautical Telecommunication Network Routing Domain
ATN RDC : Aeronautical Telecommunication Network Routing Domain Confederation
ATNC : ATN and Communication Architecture
ATNI : Aeronautical Telecommunication Network Internet
ATNP : Aeronautical Telecommunication Network Panel (ICAO)
ATNSI : ATN System Inc. (US)
ATO : Actual Time Overhead of Overflying (CFMU - CASA)
ATO : Airborne Traffic Observation
ATOC : Allied Tactical Operations Centre
ATOPS : Advanced Transport Operating System
ATOT : Actual Take Off Time

ATP : At…(time or place)
ATRAC : Air Navigation Services Employee Training Concept
ATRACC : ATC System for Riga Area Control Centre
ATRK : Alone Track Error
ATS : Air Traffic Services

ATS : Automatic Throttle System

ATSA : Air traffic Services Authority (Bulgaria &Croatia)

AT-SAT : Air Traffic Selection and Training  
ATSD : Air Traffic Situation Display

ATSC Air Traffic Service Communications (Communications related to air traffic services. This includes ATC, aeronautical and meteorological information, position reporting and services related to safety and regularity of flight)

ATSEP : Air Traffic Safety Electronics Personnel
ATSIS : Air Traffic Services Investigation System
ATSN : Air Traffic Service Network
ATSO : Air Traffic Services Operator
ATSORA : Air Traffic Services Outside Regulated Airspace
ATSP : Air Traffic Service Providers
ATSSD : ATS Standards Department
ATSU : Air Traffic Service Unit
ATSup : Air Traffic Supervisor
ATT : Along Track Tolerance
ATT : Attitude Indicator

ATTN : Attention
ATWR : Apron TWR

ATYP :  Aircraft Type
ATZ : Aerodrome Traffic Zone
AU : Arbitrary Unit

AU : Australia (ISO Country Code)

AUA : ATC Unit Airspace
Aud : Audio aids
AUP : Airspace Use Plan
AUS : Airspace Utilisation Service
AUSTRO CONTROL : Österreichische Gesellschaft für Zivilluftfahrt mbH (AT)

AUTH : Authority

AUTH : Autorized or Authorization

AUTOB : Automatic Weather Reporting System
AUTOCAD : Automatic Computer Aided Design
AutoNav : Auto-Navigation
AUTOVON : Automatic Voice Network

AUW : All Up Weight

AUX : Auxilliary
AV : Audio-visual aids

AV : Avianca

AVAIL : Available

AVBL : Available

A-VASIS : Advanced Visual Approach Slope Indicator System
AVENUE : ATM Validation Environment for Use towards EATMS

AVG : Average

AVGAS : Aviation Gasoline

AVHRR Advanced Very High-Resolution Radiometer

AVI : Audio/Video Interleaved
AVOL : Aerodrome Visibility Operational Level
AVPAC : Aviation VHF Packet Communications
AW : Area Width
AW : Aerial Work
AW/P : Active Way Point
AWACS : Airborne Warning and Control System

AWAS Automated Weather Advisory Station

AWIPS Advanced Weather Interactive Processing System

AWIR : Automatically generated What-If Re-routing
AWOG : All Weather Operations Group
AWOP : All Weather Operations Panel (ICAO)
AWOS : Automatic Weather Observing System
AWP : Ancillary Working Position
AWP : Arrival Waypoint

AWR/Rn : Alternative flight plan on the basis of the Aircraft Operator „What-If“ Re-route Function (AOWIR), whereby „n“ designates the current number of the AOWIR alternative flight plan

AWTA : Advise at What Time Table
AWX : All Weather
AWY : Airway

AY : Finnair (airline)
AZ : Aerodrome zone

AZ : Alitalia (airline)
AZ : Azerbaijan (ISO countries Codes)

AZM : Azimuth




B : At or Below (constrained altitude)

B : Belgium

B : Blue
B&D : Bearing and Distance
B&H : Bosnia and Herzegovina
B/C : Benefit / Cost
B/CRS : Back Course
BA  : Barometric Altitude
BA : Bosnia and Herzegovina (ISO Country Code)

BA : Breaking Action

BA : British Airways (airline)
BAA : British Airport Authority
BADA : Base of Aircraft Data ; Aircraft performance Data Base
BAF : Belgian Air Force

BA FAIR : Braking action Fair

BALPA British Air Line Pilots Association

BA NIL : Braking Action Nil

BA POOR : Braking Action Poor
BARS : Behaviour Anchored Rating Scales
BARTCC : Berlin Air Route Traffic Control Centre

BASE : Cloud Base
Base AM : Base Arrival Manager
Base AMD : Base Arrival Manager Display

BASIS British Airways Safety Information System
BAST : Basic ATC Skills Trainer
BATAP : `Type-B' Application To Application Protocol
BAZ : Bundesamt für Zivilluftfahrt (Austria) (AT) / Austrian aviation authority

BC : Patches (meteo)

BC : Back Course
BCA : Border Crossing Authority
B-CAS : Beacon Collision Avoidance System
BCBP : Bilateral Communication Plan Co-ordination
BCD : Binary-Coded Decimal

BCFG : Fog Patches

BCMT : Beginning of Civil morning twilight

BCN : Beacon

BCST : Broadcast
Bd : Baud

BD : British Midland (airline)
BDP : Brussels ACC Computer
BDR : Battle Damage Repair

BDRY : Boundary
BE : Belgium (ISO Country Code)

BECMG : Becoming (meteo)
BEM : Boundary Estimate Message (SARP)
BENELUX : Belgium, Netherlands and Luxembourg
BER : Bite Error Rate

BERM : Snowbank(s) Containing Earth/Gravel

BF MarkAir

BFD : Basic Flight Data message
BFL : Blocked Flight Level Area

BFR : Before
BFWG : Budgetary and Financial Working Group
BG : Bulgaria (ISO Country Code)
BGD : Background
BHL-System : (Name of HR-registration system)
BIAC : Brussels International Airport Company
BIF : Deliver Implementation Benefits Faster (EATCHIP Adaptation)
BIRDTAM : NOTAM on Bird Activity
BIS : Boundary Intermediate System
BIST : Build-In Self Test 
BIT : Built-In Test
BITE : Built-In Test Equipment

BKN : Broken (meteo)

BL : Blowing (meteo)

BLDG : Building

BLO : Below clouds

BLW : Below

BMUN : Better Meet User Needs (EATCHIP Adaptation)
BN : Backbone Node (RMCDE/ RADNET)
BNC : Backbone Network Computer

BND : Bound
BNF : Backus Naur Form
BNL : Benelux
BOI : Biographical Oriented Interview

BOMB : Bombing
BOS : Behaviour anchored Rating Scales
BP : Business Plan
BPF : Band Pass Filter
BPN : Boundary Point of Entry
bps : bits per second
BPS : Boundary Point Sector
BPSK : Binary Phase Shift Keying
BPSX : Boundary Point Sector Exit

BR : Mist (meteo)

BR : Brazil (ISO Country Code)

BR : Eva Air (airline)
BRA : Basic Rate Access
BRA : Bearing, Range and Altitude

BRF : Short (used to indicate the type of approach desired or required)

BRG : Bearing
BRITE : Basic Research in Industrial Technologies for Europe = EURAM
B-RNAV : Basic Area Navigation

BRNAV : Basic Air NAVair Traffic Control Unit

BRKG : Braking

BRT Brightness
BS : Band Stop (ACS)
BS : BootStrap (RADNET Introduction - MAS)

BS : Commercial Broadcasting station
BSC : Binary Synchronous Communications 
BSP : Aircraft Parameter Downlink (service)
BSS : Best Signal Selection 
BSU : Beam Steering Unit
BTC : Basic Training Course
BTEC : Business and Technician Education Council
BTH (R) : Beyond the Horizon (Radar)

BTL : Between Layers

BTN : Between
BVR : Beyond Visual Range
BW : Bandwidth
BWP : Budget and Work Programme Planning
BY : Belarus (ISO countries Codes)

BYD : Beyond




C : Centre (runway indentification)

C : Degree Celcius

C/A Code : Course / Acquisition Code
C/d : Capacity demand ratio
C/M : Carrier-to Multi-Path Ratio
C/N : Carrier-to-Noise Ratio
C/N0 : Carrier-to-Noise-Density Ratio
C/S : Call Sign
C102 (TSO) : Helicopter Radar Approach, Issued 04/02/84 (RTCA DO-172, Issued 03/83)
C104(TSO) : Microwave Landing System (MLS) Receiving Equipment, Issued 06/82 (RTCA DO-174, Issued 03/82)
C105(TSO) : Optional Display For Weather Radar, Issued 06/84 (RTCA DO-174, Issued 03/81)
C110(TSO) : Airborne Thunderstorm Detector, Issued 01/01/01,(RTCA DO-187, Issued 11/84
C115(TSO) : RNAV Equipment Using Multi-Sensor, Issued 06/86 (RTCA DO-187, Issued 11/84)
C118(TSO) : Airborne TCAS I Equipmen4 Issued 08/88 (RTCA DO-197, Issued 3/87)
C119(TSO) : Airborne TCAS II Equipment (RTCA Do-185, Issued 09/83)
C120(TSO) : RNAV Equipment Using OMEGA/VLF, Issued 01/88 (RTCA DO-185 issued 9/83)
C2 level : Security level in the United States Department of Defense
C31d(TSO) : High Frequency (HF) Communications Transmitting Equipment, Issued 04/84 (RTCA DO-163, Issued 03/76)
C32d(TSO) : High Frequency (HF) Communications Receiving Equipment, Issued /83
C34e(TSO) : ILS Glide Slope Receive Equipment, Issued 01/88 (RCTA DO-192, Issued 07/86)
C35d(TSO) : Radio Marker Receiving Equipment, Issued 04/71 (RTCA DO-143, Issued 01/70)
C36e(TSO) : ILS Localizer Receiver Equipment, Issued 01/88 (RTCA) DO-195, Issued 11/86)
C37d(TSO) : VHF Comm transmitting Equipment, Issued 08181 (RTCA DO-157, Issued 08/81 (RTCA DO-157, Issued 08/74)
C38c(TSO) : VHF Comm Receiving Equipment; Issued 08/81 (RTCA DO-156, Issued 08/74)
C38d(TSO) : VHF Comm: Receiving Equipment, Issued 08/81 (RTCA DO-186, Issued 1/84)
C3CM(TSO) : Command, Control and Communications Countermeasures
C3T : Controller Tools and Transition Trials. See EVP.
C40c(TSO) : Airborne VOR Receiving Equipment, Issued 01/88 (RTCA DO-1996, Issued 11/86)
C41d(TSO) : Airborne ADF Equipment, Issued 05/86 (RTCA DO-179, Issued 05/82)
C50c(TSO) : Audio Selector Panel and Amps, Issued 01/83 (RTCA DO-170, Issued 01/80)
C57a(TSO) : Headsets And Speakers, Issued 01/83 (RTCA DO-170, Issued 01/80)
C58a : Aircraft Microphones, Issued 01/83 (RTCA DO-170, Issued 01/80)
C59 : Selective Calling (SELCAL) Equipment, Issued 01/01 (RTCA DO-93, Issued 2/59)
C60b : RNAV Equipment Using LORAN -C, Issued 05/88 (RTCA DO-194, Issued 11/86)
C63c : Airborne Weather Radar, Issued 08/83 (RTCA DO-173 Issued 11/80)
C65a : Doppler Radar Air Speed Equipment, Issued 08/83 (RTCA DO-158, Issued 11/75)
C66b : Airborne DME (Distance Measuring Equipment), Issued 08/81 (RTCA DO-1514, Issued 04/60)
C67 : Airborne Radar Altimeters, Issued 11/64 (RTCA DO-103, Issued 4/60)
C68a : Dead Reckoning Computer Equipment, Issued 08/83 (RTCA DO-158, Issued 10/75)
C74e : Airborne ATC Transponder Equipment, Issued 01/01 (RTCA DO 161A, Issued 05/76)
C87a : Low Range Radar Altimeters, Issued 01/01 (RTCA DO-155, Issued 01/74)
C91a : Emergency Locator Transmitter, Issued 04/85 (RTCA DO-183, Issued 5/83)
C92b : Ground Proximity Warning (GPWS) Equipment, 01/01 (RTCA DO-161A, Issued 05/76)
C94a : OMEGA Receiving Equipment, Issued 08/81 (RTCA DO-164A, Issued 09/79)

C : Centigrade

CA : Canada (ISO Country Code)
CA : Civil Aviation
CA : Conflict Alert
CA : Course to an Altitude (ARINC 424 Path Terminator)
CAA : Civil Aviation Authority (Great Britain)

CAAC : Civil Aviation Authority of China

CAAS : Class A Airspace
CAAS : Computer Aided Approach Sequencing

CAB : Civil Aeronautics Board
CAC : Centralised Approach Control
CAD : Computer Aided / Assisted Design
CADAS : Computer Controlled Avionics Data Acquisition System
CADF : Centralised Airspace Data Function (ECAC)
CADIN : Czech Automated Data Interchange Network
CADS : Combined Arrival and Departure Sequencing/Study (APATSI)
CADS : Computer aided Departure System
CAE : Computer Aided Engineering
CAEP : Committee on Aviation [Environmental] Protection Emissions Operational (Measures Working Group, WG/4) ; Commission on Aviation Environmental Protection (ICAO)
CAERAF : Common American-European Reference ATN Facility

CAI : Civil Aviation Inspection
CAI : Computer Assisted Input
CAIIS : Computer Aided Imagery Interpretation System
CAIR : Confidential Aviation Incident Reporting
CAIRDE : Civil Aviation Integrated Radar Display Equipment (IRE)
CAL : Computer Aided Learning
CALLSGN : Callsign
CALM : Computer Assisted Landing Management System
CALS : Computer-aided Acquisition and Logistic Support
CAM : Computer Aided Manufacturing
CAM : Conflict Alert Message
CAMI : Civil Aeromedical Institute
CAMOS : Central ARTAS Maintenance & Operational Support
CAMPS : Computer Aided Message Processing System
CAMUS : Czech Automated Multi radar System
CAN Proj. : Croatian Air Navigation Project
CANAC : Computer Assisted National ATC Centre (B)
CANSO : Civil Air Navigation Services Organisation
CAO : Computer Assisted Operations
CAOFA : Co-ordination of Air Operations in the Forward Area
CAP : Combat Air Patrol
CAP : Controller Access Parameters
CAPAN : Capacity Analyser
CAPC : Civil Aviation Planning Committee 
CAPE : Computer Assisted Planning Experiment

CAPP : CFMU/DEVD - Client Applications Section
CAPSIN : CAA Packet Switched Integrated Network (UK)
CAR : Caribbean Region
CARAT : Computer-Aided (Assited) Route Allocation Tool
CARD : CNS Applications - Research and Development
CARD : Conflict And Risk Display (ODID)
CARE : Co-operative Actions of ATM Research and Development in Eurocontrol
CARFE : Conference on Airport and Route Facility Economics (ICAO)
CART : Classification And Regression Trees
CAS : Calibrated (Computed) Air Speed
CAS : Close Air Support
CAS : Collision Avoidance System
CAS : Computerised Assessment System
CASA : Computer Assisted Slot Allocation 
CASE : Computer Aided Software Engineering
CASI : CFMU Aircraft Situation Image
CASOR : Civil Area Services Operations Room
CAST : Consequences of future ATM systems for air traffic controller Selection and Training
CASTA : Controller Associate for Strategic and Technical Advice
CAT x : Category x Precision Approach (I, II of III)

CAT I Facility providing operation down to 200 feet decision height and runway visual range not less than 2600 feet.

CAT II Facility providing operation down to 100 feet decision height and runway visual range not less than 1200 feet.

CAT II a Facility providing operation with no decision height limit to and along the surface of the runway with external visual reference during final phase of landing and with a runway visual range not less than 700 feet.

Cat : Category
CAT : Clear Air Turbulence

CAT : Computer Aided Testing

CAT : Commercial Air Transport
CAT : Computer Assisted Teaching / Training
CAT : Continuous Attention Task
CATCAS : Copenhagen Air Traffic Control Automated System (DK)
CATCO : Chief ATC Operations

CATIA : TF on CNS/ATM Implementation Aspects
CATSA : Croatian air Traffic Services Authority
CATSIM : CAA Air Traffic Simulator (UK)
C-ATSU : Controlling ATS Unit
CAUTRA : Automated Computer System for Air Traffic

CAVOK : Clouds and Visibility OK (Visibility, cloud and presend weather better than prescribed values or conditions)
CB : Central Battery

CB : Suckling Airways (airline)
CB : Cumulonimbus
CBA : Cost Benefit Analysis
CBA : Cross Border Area

CBAS : Class B Airspace

CBSA : Class B Surface Area
C-Band : Frequency Band
CBI : Computer Based Instruction
CBN : Common Backbone Network (subnetwork RAPNET = system of the national ATS, DFS = PSN)
CBPM : Computer-Based Performance Measure
CBS : Cost/Benefit Studies
CBT : Computer Based Tool
CBT : Computer Based Training

CC : Contractual Conditions

CC : Cirrocumulus

CCA : (or CCB, sequence) corrected meteorological message (message type designator)

CCAS : Class C Airspace
CCB : Change Control Board
CCC : Cellular CNS Concept
CCC : Central Computer Complex
CCC : Command, Control and Communications
CCC : Common Core Content (of ATC Training)
CCCC : Cross Channel Co-ordination Centre
CCCI, C3I : Command, Control, Communications and Intelligence (network)
CCDS : Code Callsign Distribution System
CCF : Centralised Control Function (LATCC)
CCFT : Cold Cathode Fluorescent Tube
CCG : CEATS Co-ordination Group
C-Channel : Circuit Mode Channel
CCIP : Code-Callsign Input Position 
CCIS : Closed Circuit Information System
CCL : Code Callsign List

CCLKWS : Counterclockwise
CCM : Computerized Control and Monitoring
CCMS : Committee on the Challenges of Modern Society 
CCP : Circuit Switched Public Data Network
CCP : Configuration Control Plan
CCR : Cancel Contract Request
CCS : Code CallSign

CCSA : Class C Surface Area
CCTV : Closed Circuit TeleVision
CCW : Counter-Clockwise

CD : Candela
CD : Conflict Display (ODID)
CD : Council Directive
CD : Course to a DME Distance (ARINC 424 Path Terminator)
CD&A : Conflict Detection and Avoidance
CD2 : Common Digitizer 2
CD-2 : Transmission format for radar data
CDA : Client Defined Area 
CDA : Conflict Display Area. Coordination Approval / CoorDination Acceptance (message)
CDA : Current Data Authority (ICAO)
CDB : Central Data Base
CDG : Roissy Charles-de-Gaulle Airport
CDI : Coordination Information
CDI : Course Deviation Indicator
CDM : Collaborate (Cooperative) Decision Making (central supporting features of gate to gate, and for enhancing capacity [airports])

CDMA : Code Division Multiple Access
CDN : Airspace Crossing Co-ordination Message / Co-ordination (message type designator)
CDP : Central Data Processing
CDP : Computer Diagnostics Program
CDPS : Central Data Processing System

CDR : Coded Departure Routes. Predefined routes used to route air traffic around areas of severe weather.
CDR : Conditional Route
CDR : Conflict Detection and Resolution
CDR : Co-ordination Request (message)
CDR : Critical Design Review
CDRL : Contracts Data Requirements List (MAS/DFS - ODS)
CD-ROM : Compact Disk / Read Only Memory
CDS : Controller Display Support
CDSEPT : Committee to Develop Standards for Educational and Psychological Testing of The American Educational research Association, The American Psychological Association, and The National Council on Measurement in Education.
CDT : Command Delivery Time
CDTI : Cockpit Display of Traffic Information
CDTS : Console Detailed Technical Specification
CDU : Control and Display Unit (pilots' interface to the FMS)
CE : Committee of Management  
CE : European Commission / Commission européenne
CEAC : Committee for European Airspace Co-ordination (NATO Group) renamed on 27.4.98 by the North Atlantic Council (=NATMC)

CEAS : Class E Airspace
CEATS : Central European Air Traffic Services (Austria, Croatia, Czech Republik, Hungary, Italy, Slovakia and Slovenia [Bosnia, Herzegowina])
CEATS LSG : Central European Air Traffic Services Legal Sub Group
CEATS UAC : Central European Air Traffic Services Upper Airspace Control Centre
CEC : Commission of the European Communities ; European Commission / Commission des Communautés Européennes (=CEE) ; Commission européenne
CEECs : Countries of Central and Eastern Europe ; Central and Eastern Europe Countries
CEF : Capacity Enhancement Function
CEFA : Co-operation for Environmentally Friendly Aviation (ERA, ACI, AEA, AECMA, EBAA, EUROCAE)
CEO : Chief Executive Officers
CEP : Circular Error Probable
CER : Cancel Emergency Mode Request
CES : Central and Eastern European States

CESA : Class E Surface Area
CESAR : Course Evaluation Sheets Analysis and Reporting
CESC : Chief Executive Standing Conference (see CEO)
CEU : Central Executive Unit (ATM / CFMU)

CEU-E : Central executive unit with Responsibility for Eastern Europe

CEU-W : Central executive unit with Responsibility for Western Europe

CEW : Civil Engineering Works

CF : Change frequency to….
CF : Course to a Fix (ARINC 424 Path Terminator)
CFAR : Constant False Alarm Rate (or Regulation)
CFB : Central Flight plan Bank
CFCF : Central Flow Control Facility 
CFD : Change to Flight Data Message
CFDS : Central Flight Data Suite (PALLAS system)
CFE : Customer Furnished Equipment
CFEP : Communications Front End Processor

CGL : Circling Guidance Light(s)
CFIT : Controlled Flight into Terrain
CFL : Cleared (Current) Flight Level
CFM : Central Flow Management (services)
CFM : EEC business area - support to ATFM 
CFMU :  Central Flow Management Unit

CFMUSC : CFMU Steering Committee
CFTPD : Central File of Transponder Performance Data (ECC)

CFR : Code of Federal Regulations
CG : Center of Gravity

CGAS : Class G Airspace

CGS Centimeter-gram-second

CH : Channel

CH : Switzerland (ISO Country Code)
CHA : Character
CHAID : Chi Square Automatic Interaction Detection

CHAN : Channel
Chap. : Chapter
CHG : Change Message

CHG : Change of Modification
CHI : Computer-Human Interface
CHIEF : Project Switzerland (CH), Italy (I), Spain (E), France (F)
CHIRP : Confidential human Factors Incident Reporting Programme

CHMI : CFMU Human Machine Interface

CI : Cirrus
CI : Configuration Item

Cl : Cost Index

CI : China Airlines (airline)
CI : Course to Intercept (ARINC 424 Path Terminator)

CIA : CFMU Internet Application
CIADN : Croatian Integrated Aeronautical Data Network
CIC : Clearances and Information Communications
CICT : Convergence and Implementation Coordination Team (renaming of SICT)
CID : Computer Interface Device
CIDIN : Common ICAO Data Interchange Network
CIEL : Common Interface Exchange Language

CIG(s) : Ceiling(s)
CIM : Customer Information Management
CIMIL : Civil/Military Co-ordination
CINCAT : Capacity Increase through Computer Assistance Tools
CINCENT : Commander in Chief Central Europe
CINTIA : Control of Inbound Trajectories of Individual Aircraft
CIO : Conventional International Origin
CIP : CFMU Implementation Plan
CIP : Convergence and Implementation Programme

CIS : Commonwealth of Independent States (States of former USSR)

CIS : Cooperative Independent Surveillance
CIS : Critical Incident Stress
CISD : Critical Incident Stress Debriefing
CISM : Critical Incident Stress Management (HRT)
CISMO : Centralised International System Management Organisation

CIT : Compressor Inlet Temperature
CIT : Critical Incidence Technique

CIT : Near or over large towns
CITRAC : Common Interface for Trajectory Calculation
CIU : Cabin Interface Unit
CIV : Civil
CJEC : Court of Justice of The European Communities (=CJEC, COJEC now European Court of Justice)
CJI : Controller Justification Indicator

CK : Check

CL : Centre Line
CL : Cleared
CL : Connectionless Mode Service

CLA : Clear type of ice formation
CLA : OCM Clearnace Echoback Message (message in the OCM Service)

CLB Climb Detent of the Thrust Levers

CLBR : Calibration

CLD : Cloud
CLD : DCL Clearance Message (message in the DCL Service)

CLG : Calling
CLIMAX : Multi-station carrier offset mode, with voting override

CLKWS : Clockwise
CLNP : Connection Less Network Protocol
CLNS : Connection Less Network Service

CLR : Clear or cleared to or clearance

CLSD : Closed
CLTP : Connection Less Transport Protocol
CLW : Communications List Window
CLX : OCM Clearance Message
cm : Centimeter
CM : Configuration (Context) Management
CM : Common Memory (CBN - CNG)
CM : Conformance Monitoring
CM : Critical Milestone (MAS/DFS - ODS)
CMA : Central Monitoring Agency (NAT)
CMA : Context Management Application

CMB : Climb
CMB : Combined (PSR and SSR)

CMC Central Maintenance Computer
CMC : Central Master Clock
CMC : Constant Mach Blimb
CMCSG : Civil and Military Co-ordination Sub-Group
CMG : Crisis management Group
CMIC : Civil Military Interface Standing Committee (New Convention)

CMIP : Contract Management and Inspection Procedures
CMIS/CMIP : Common Management Information System / Protocol
CMMC : Central Monitoring and Management Centre
CMMC : Common Maintenance Monitoring and Control
CMOS : Complementary Metal Oxid Semiconductor

CMPL : Completed or Completion or complete
CMS : Central Message Switch
CMS : Common Modular Simulator (CMTP)
CMSA : Carrier Sense Multiple Access (ICAO-ADS)

CMSND : Commisissioned
CMT : Core Management Team
CMT : Critical Milestone Test (MAS/DFS - ODS)
CMTP : Common Medium Term Plan

CMU : Communications Management Unit
CMV : Coverage Measurement Volume
CN : Change Notice

CN : China (ISO Country Code)
CN : Common Network (INTNET/RADNET)
CN : Permanent Commission for the safety of air navigation
CNACC : Common National Area Control Centre
CNATCC : Common National Air Traffic Control Centre (Bulgaria)
CNG : Common Network Group
CNL : Cancel(lation) message (ICAO)
CNS : Communication, Navigation and Surveillance
CNS : Study Group of Alternates
CNS/ATM : Communication, Navigation and Surveillance / Air Traffic Management
CNS/ATM-1 : Communication, Navigation and Surveillance / Air Traffic Management Package 1

CNTRLN : Centerline
CO : Connection Mode Service

CO Continetnal
COBALT : Common Objective Alignment Team
COBT : Calculated Off Block Time 
COC : Combat Operations Centre or Concept
COCESNA : Central American Corporation For Air Navigation Service
COCOS : Computer Controlled SSR Code Assignment Procedures
COD : Common Medium-Term Plan Overview Document
CODA : Central Office of Delay Analysis

CODE : Aircraft address (expressed in the form of an alphanumerical code of six hexadecimal characters) when required by the appropriate ATS authority

CODEC : Coder/Decorder (ACS)
CoE : Centre of Expertise
COF : Change of Frequency
COFA : Comando Operacional Força Aérea (PT)
COFAR : Common Options for Airport Regions
COFEE : Consolidated (Checked) Operational data FEEder
COG : Coordination Group (meeting of the EANPG Programme) ICAO
COHO : Coherent Oscillator
COLL : Collapse
COLOC : Change of Location of Command

COM : Cockpit Operating Manual
COM : Communications (ICAO)
CoM : EUROCONTROL Committee of Management
COM/DIV : ICAO Communications Divisional Meeting
COM/MET : Communications / Meteorology Divisional Meeting
COM/OPS : Communications / Operations
COMALF-E : Commander of Airlift Forces - Europe
COMED : Combined Map and Electronic Display
COMG : Communications Group
COMIL : Coordination Centre for Military Airspace Use 
COMIL-1N : ATS Coordination Centre for Military Airspace Utilisation - Phase 1 Network
COMLAN : COMmunication Local Area Network
Comm-B  : Mode S downlink format DF20 or 21
COMNAV : Groupe de travail sur les Télécommunications et les installations de navigation (CEAC)
COMP : Operating Company
COMPAS : Computer Oriented Metering Planning and Advisory System 
COMSEC : Communications Security
COMT : Communications Team
COMX : Undefined Future Communication System 
CON : Continuous

CONC : Concrete

COND : Condition

CONDAR : Conflict Detection and Resolution
CONDOR : Confidential Direct Occurence Report
CONF : Conflict
CONFACP : Conflict Accept
CONOPS : Concept of Operations of Mode S in Europe
CONP : Connection Oriented Network Protocol

CONS : Continuous

CONST : Construction or Constructed
CONT : Continue
Cont'd : Continued
CONUS : Continental United States
COO : Coordinator

COOR : Co-ordinate or coordination
COORD : Co-ordination

COP : Change over Point
COP : Contingency Operations Plan
COP : Co-ordination Point 
COPG : Common Operating Procedures Group
COPP : Connection Oriented Presentation Protocol
COPS : Common Operational Performance Specifications

COR : Correct or Corrected or Correction
COR : Correlate
CORA : Conflict Resolution Assistant
CorC++ : Computer language
CORE : Controlled Requirements Expression
CORE : CORE Requirements for ATM Working Positions
COROM : Cognitive Competencies Model

CO ROUTE Company Route (also CO RTE)

CORUM : Training and Human Resources Consultancy Company
COS : Chief of Staff
COS : Computer Operating Station
COSAAC : Common Simulator to Assess ATMF Concepts
COSP : Connection Oriented Session Protocol
COSPAS : Space system for the search of vessels in distress (translate. from Russian)
COST : (European) Cooperation in the Field of Scientific and Technical Research

COSU : CFMU/ENGD - Core Systems Unit
COSYNUS : AIRBUS Training Database

COT : At the Coast
COTP : Connection Oriented Transport Protocol

COTR Contracting Officer's Technical Representative
COTS : Commercial Off-The-Shelf (System)

COV : Cover or Covered or Covering
CP : Circular Polarisation
CP : Conflict Probe (PATs)
CP : Contact Person (Eurocontrol)

CP : Control Panel
CP : CWP Processor Unit
CPA : Closest Point of Approach
CPC : Constant Pitch Climb
CPC : Control and Processing Centre
CPCs : Certified Professional Controllers

CPCS : Cabin Pressure Control System
CPD : Continuous Professional Development

CPD : Coupled
CPDLC : Controller Pilot Data Link Communications
CPF : Central Processing Facility
CPI : Californian Psychological Inventory
CPL : Commercial Pilots License
CPL : Current Flight Plan (message)
CPL : Customer Priority Listing (NOG)
CPR : Conflict Prediction and Resolution
CPS : Central Print Service  / Central Processing System
CPS : Characters Per Second
CPU : Central Processing Unit
CR : Central Region
CR : Course to a VOR Radial (ARINC 424 Path Terminator)
CR : Czech Republic
CR(A)OC : Central Region (Air) Operations Centre
CRAF : Central Reservation Airspace Facility
CRAF : Civil Reserve Air Fleet
CRAF : Computer Resolution Advisory Function
CRAFS : Civilian Request for Airspace and Flight Data System
CRAM : Conditional Route Availability Message
CRATF : Communications Requirements Analysis Task Force
CRC : Control and Reporting Centre
CRC : Cyclic Redundancy Check
CRCO : Central Route Charges Office 
CRD : Conflict Risk Display
CRDA : Converging Runway Display Aid
CRDS : CEATS Research & Development & Simulation Centre
CRDS : Colour Raster Scan Display
CREME : Creating the EATCHIP Management Environment
CRF : Central Repair Facility (RMCDE - MAS)

CRITTER Civil Rotorcraft IFR Terminal-Area Technology Enhancement Research
CRM : Cockpit / Crew Resource Management
CRM : Collision Risk Modelling (ICAO - ADS)
CRM : Co-ordination Revision Message
CRMCS : Central RADNET Monitoring and Control System
CRNA : Centre Régional de la Navigation Aérienne (DGAC/DNA/SCTA, France)
CRS : Contingency Routing System
CRS : Controller Route Sequence (FPPS/DECADE)

CRS : Course
CRT : Choice Reaction Time

CRZ : Cruise
CS : Callsign or Contract Signature

CS : Cirrostratus

CS : Collapsed Sector
CSAC : Cooperative Structural Airspace Concept (ICAO)

CSAR : CFMU System Anomaly Report (FORM)
CSC : Common Signalling Channel
CSCE : Conference on Security and Cooperation in Europe

CSCW : Computer Supported Co-operative Work
CSD : Concept and System Domain

CSD Constant Speed Drive
CSD : Context and Scope Document
CSD : Context Specification Document 
CSDT : Concept & Systems Development Team
CSDT : Context and System Domain Team
CSEL : Combat survivor evader locator
CSF : Critical Success Factor (EATMS, CSD)
CSFR : Czech and Slovak Federal Republic
CSI : Combined Safety Investigation
CSI : Critical Success Indicator
CSM : Central Service Modules (RMCDE / RADNET)

CSM : Chaotic Situation Management
CSMA : Carrier Sense Multiple Access
CSMA/CD : Carrier Sense Multiple Access with Collision Detect
CSN : Channel Sequence Numbers

CSO : CFMU/ENGD/SOS - CFMU System Operations HELPDESK Team
CSP : Communication Service Provider
CSPD Unit : CEATS Strategy, Planning and Development Unit
CSPDU : CEATS Strategic Planning & Development Unit
CSR : Cursor
CSR : Customer Service Requests (NOG - database for DPN operators)
CSSR : Conventional SSR
CSU : Control Sector Unit
CSU-P : Centre Supervisor 
CT : Centre (select)
CT : Cooperative Tools (PATs)
CT : Core Tasks
CT : Core Team
CTA : Calculate Time of Arrival

CTA : Controlled-Time of Arrival
CTA : Cognitive Task Analysis

CTA : Control Area (ICAO Term)

CTAM : Climb to and maintain

CTAS Center TRACON Automation System
CTB : Co-operative Tube Based
CTC : Cancel All Contracts And Terminate Connection Request (ICAO)

CTC : Centralized Train Central

CTC : Contact
CTD : Calculated time of Departure
CTF : Communication Task Force 
CTG : Common Training Group (of AISAP)
CTI : Collegiate Training Initiative

CTL : Control
CTMO : Central Air Traffic Flow Management Organisation (ICAO concept)

CTN : Caution
CTO : Calculated Time Over
CTO : Computed Time Over (CFMU - CASA)
CTOT : Calculated Take Off Time

CTR : Center

CTR : Civil Tilt Rotor
CTR : Controller or Control Zone

CTRL Control
CTRS : Common Time Reference System 
CTS : Command Tracking Stations
CTWUEC : Committe of Transport Workers' Unions in the European Compmunity (now FST : Federation of Transport Workers' Unions in the European Union = acronym formed from its French title)
CU : Control Unit

CU : Cumulus

CUF : Cumuliform
CUG : Closed User Group
CUP : Computer Utility Program
CUP : CWP-Unit Processor
CUR : Current Sector or Centre or Controller

CUST : Customs
CV : Curriculum Vitae
CVFR : Controlled Visual Flight Rules
CVO : Code Validity Overlap
CVR : Cockpit Voice Recorder
CVR : Console Voice Recorder
CVSM : Conventional Vertical Separation Minimum

CVSRF Crew-Vehicle Simulation Research Facility (NASA Ames)
CW : Clockwise

CW : Continuous Wave
CWAR : Continuous Wave Acquisition Radar
CWBS : Contract/Complete Work Breakdown Structure
CWDPS : Central Weather Data Processing System
CWIR : CFMU Generated What-If Re-routing
CWP : Controller Working Position

CWS : Control Wheel Steering
CWS : Collision Warning System

CWY : Clearway

CX : Cathay Pacific Airways (airline)
CY : Cyprus (ISO Country Code)

CY : Cyprus Airways (airline)
CYPRO : Cyprus Project for ATC Improvements
CYTA : Cyprus Telecommunications Authority
CZ : Czech Republic (ISO Country Code)
CZM : Conventional Zero Meridian
CZW : Conflict Zoom Window (ODID)




D…: Danger Area

D : Day

D : Derated

D : Downward (tendency in RVR during previous 10 minutes)
D : Germany
D&D : Distress and Diversion
D.O.T : Department of Transport
D/A : Digital-to-Analog

D/D Drift Down
D/L : Data Link
DA : Decision Altitude
DA : Descent Adviser
DA : Dimensional Aspect
DA : Direct Access (VCS)
DA/H : Decision Altitude Height
DAA : Dynamic Airspace Allocation

DAAIS : Danger Area Activity Information Service
DAARWIN : Distributed ATM Architecture based on RNAV, Workstations, Intelligent tools, and Networks
DABS : Discrete Address Beacon System (U.S.A)
DAC : Deployable ACCS Component
DAC : Direction Aviation Civile
DAC : Dynamic Air Traffic Control Test
DACT : Dissimilar Air Combat Training
DAF : Demand Adjustment Factors

DADC Digital Air Data Computer

DAFIF : Digital Aeronautical Flight Information File
DAI : Direct Access Intercom (VCS)
DAISY : Distributed Airport Information System (RUN)
DAIW : Danger Area Altitude Warning (or Area Proximity Warning)

DALGT : Daylight

DAP : Directorate of Airspace Policy
DAP : Downlink Aircraft Parameter
DAPs : Downlinked Aircraft Parameters
DARC : Direct Access Radar Channel

DAS : Directorate ATM Strategies (Eurocontrol)
DAS : DME Based Azimuth System
DAS : Dual Attachment Station (ODS - FDDI)
DASA, Dasa : Deutsche Aerospace
DASR : Department of ATC Systems Research
DAT : Differential Aptitude Test

DATALINK Digitized Information Transfer (air/ground)
DATAS : Datalink and Transponder Analysis System
D-ATIS : Digital ATIS
DATS TF : Delegation of ATS Task Force (ANT)
D-ATSU : Downstream Air Traffic Service Unit
DAVINCI : Departure and Arrival Integrated Management System for Cooperative Improvement of Airport Traffic Flow
DB : Data Base
dB : decibel
dBi : decibel with respect to an isotropic antenna
dBm : decibel, referenced to 1 milliwatt
DBMS : Data Base/Data Bank Management System
DBS : Data Base System

DBS Direct Broadcast Satellite
dBW : decibel, referenced to 1 watt
dBZ : decibel, units of reflectivity
DC : Departure Clearance (ICAO)
DC, d.c. : Direct Current Electricity / Device Control
DCA : Department of Civil Aviation (various countries)
DCA : Director(ate) of Civil Aviation
DCAM : Department Civil Aviation of Malta
DCC : Data Country Code (CCITT X.121 Structure)

DCD : Double Channel Duplex
DCDU : Datalink Control and Display Unit
DCE : Data Circuit-terminating Equipment (RADNET / RMCDE)
DCE : Data Communications Equipment
DCF : Discounted Cash Flow
DCF77 : German time standard, emitting on 77.5 kHz with callsign DCF
DCFEP : Data (Digital) Communications Front End Processor
DCIA : Dependent Convergent Instrument Approaches

DCKG : Docking
DCL : Departure Clearance
DCM : Decomposition and Consolidation Matrix
DCM : Document Configuration Management (EATCHIP/EATM)
DCM : Downstream Clearance Message (Service)

DCMSN : Decommission

DCMSND : Decommissioned
DCOS : Deputy Chief of Staff
DCP : Display Control Panel
DCPC  : Direct Controller Pilot Communication
DCPs : Dedicated Personal Computers
DCR : Design Certification Review  
DCR : Display Control Readout (EAS)
DCRCO : Director Central Route Charges Office
DCS : Data Communications System

DCS : Double Channel Simplex
DCT : Direct (Routing)
DCT-LB : Direct Telephone - Local Battery
DCTS : Digital Communications Terminal System (UACM)
DCU : Display Control Unit
DCW : Digital Chart of the World
DDA : Downstream Data Authority
DDB : Dynamic Databank/Database
DDC : Data Display Console
DDD : Detailed Design Document
DDE : Dynamic Data Exchange
DDL : Data Description Language
DDM : Data Display Monitor
DDP : Declaration of Design Performance
DDP : Distributed Data Processing
DDU : Display Drive Unit
DE : Germany (ISO Country Code)
DEA : Data Exchange Agreement
Debrief : Debriefing

DEC Digital Equipment Corporation
DECCA : Hyperbolic Area Navigation System

DECR Decrement

DED : Director EATCHIP Development (in the former Agency structure)

DEE : Data Entry Equipment
DEEC : Director of the Eurocontrol Experimental Centre
DEFAMM : Demonstration Facilities for Airport Movement Management (Alcatel) (F)
DEG : Data Environment Generator 
Deg : Degrees (Radar Standard)

DEGS : Degrees
DEI : Directorate EATCHIP Implementation (in the former Agency structure)
DEL : Delete
DEL : Deliverable
DEM : German Marks
DEMETER : Distance Measuring Equipment Tracer
DEMETER : DME Metering (analysis tool for DME coverage / NAVSEP)
Demo : Demonstration
DEP TC : Departure Tactical Controller
DEP : Depart, Departure (Message)
DEPA : Departure Airfield
DEPCOS : Departure Coordination System

DEP PROC : Departure Procedure
DEP-VKL : Departure Controller
DER : Departure End of the Runway
DERA : Defense Evaluation and Research Agency (UK)

DERD-X : Display of Extracted Radar Data - Extention (-Mini Computer)
DERD-X/XL : Display of Extracted Radar Data - Expanded/Expanded with LAN
DES : Data Exchange System
DES : De-Suspension Message

DES : Descent

DES : Draft Eurocontrol Standard Document
DESC : Descending
DEST : Destination Aerodrome (Airfield)
DETF : Data Exchange Trest Facility

DE-TO PR Derated Takeoff Engine Pressure Ratio

DE-TO Nl Derated Takeoff Engine Fan Speed

DETR : Department of the Environment, Transport and the Regions (UK)

DETRESFA : Distress Phase

DEV : Deviation  
DEV : Domain Executive View

DEVD : CFMU – Development Division
DF : Direct to a Fix (ARINC 424 Path Terminator)
DF : Direction Finding or Display Field (VCS)
DF : Directorate Finance / Direction des Finances
DFDAU : Digital Flight Data Acquisition Unit

DFDR Digital Flight Data Recorder

DFGS/C Digital Flight Guidance System/Computer
DFIS : Data Link Flight Information Service (ICAO)
DFL : Division Flight Level
DFL : Dynamic Flight Leg
DFS : Detailed Functional Specification (CBN - CNG)
DFS : German ATC Corporation (Deutsche Flugsicherung GmbH)
DFTI : Distance from Touchdown Indicator

DGAC : Direction Générale de l'Aviation Civile (F)
DGCA : Director General of Civil Aviation of ECAC Member States
DGE : Director General Eurocontrol
DGNSS : Differential Global Navigation Satellite System
DGOF : Director General's Office
DGON : Deutsches German Institute for Navigation
D-GPS : Differential Global Positioning System (ICAO - ADS)
DGS : Director General Secretariat
DGVII : Directorate General of Transport / European Commission
DH : Decision Height
DHMI : Devlet Hava Meydanlari Isletmesi (TU) / State Agency for Aisports and air Traffic Control (Turkey)
DHP : Direct Host Processor
DHR : Directorate Human Resources
Di : Detectability
DIADAM : Distributed ATM Data Management
DIANS : Director Institute of Air Navigation Services
DIB : Directory Information Base
DICE : Direct Course Error
DID : Direct Identification Data

DIF : Diffuse
DIGEST : Digital Exchange Standards
DIL : Data Items List
DILCS : Dedicated Intelligence Loop Circuits System
DIN : Deutsche Industrie Norm

DIR Direct

DIR/INTC Direct Intercept
DIRA : Department for Interdisciplinary Relations of Aviation
DIRCAM : Direction de la Circulation Aérienne Militaire
DIS : Data Displayed
DIS : Directorate Infrastructure ATC Systems and Support (Eurocontrol, EATM)

DIS : Distance

DISABLD : Disabled

DISCR : Discrepancy
DIS/HUM : ATM Human Resources Unit (also know as HUM unit)

DIST : Distance
DIV : DIVert(ing) or DIVerging
DK : Denmark (ISO Country Code)
DL : Data Link

DL : Delta

DL : Delta Airlines (airline)

DLA : Delay or Delayed (Message)
DLA : ATS message indicator for delay (ICAO)
DLARD : Data Link Application Requirements Document (Description) (ICAO)
DLASD : DL Application System Document
DLCRD : Data Link Communication Requirement Document
DLF : Data Link Frame
DLH : Deutsche Lufthansa (Germany)
DLIC : Data Link Initiation Capability (ICAO)
DLL : Data Link Layer
DLL : Delay Locked Loop

DLP Data Link Processor (the FAA's ground automation system that supports the Mode S subnetwork (GDLP), internetwork (ATN router) and non-ATC data link application processes)
DLPU : Data Link Processing (Processor) Unit
DLR : German Aerospace Centre (formerly the `German Aerospace Research Institute)
DLS : Data Link Splitter

DLT : Delete

DLY : Daily
DLW : Departure List Window (ODID)

DM : Maerks Air Denmark (airline)
DM : Departure Manager (PATs)
DMA : Decision Making Aids
DMA : Defense Mapping Agency
DMA : Direct Memory Access
DMA : Divergence Monitoring and Alert
DMAN : Departure Manager
DMAS : Director Maastricht Control Centre

DMC : Display Management Computer
DMC : Detachment of Military Coordinators
DME : Distance Measuring Equipment
DME/P : Precise DME
DML : Data Manipulation Language

DMR : Data Modification Reques
DMS : Database Management System

DMSTN : Demonstration

DMU : Data Management Unit
DNAs : ECAC Directors of Air Navigation

DNG : Danger or Dangerous
DNIC : Data Network Identification Codes (CCITT X.121 Structure)
DNS : Digital Network Signalling

DNTKFX : DownTrack Fix

DOC : Designated Operational Coverage
DOC : Direct Operating Cost
DOC : Document (ICAO)
DoD MIL : Department of Defence - military
DoD : Department of Defence (US)
DODAR : Diagnosis, Options, Decision, Assessment and Revision
DOF : Date of Flight  
DOI : Department of Industry

DOM : Domestic
DOP : Daily Operations Plan
DOP : Dilution of Precision
DORA : Directorate Operational Research and Analysis (UK)
DOS : Disk Operating System

DOT Department of Transportation
D-OTIS : Data Link Operational Terminal Information Service
DOTS : Dynamic Ocean Tracking System

DP : Dewpoint Temperatue
DP : Discussion Paper
DP&P : Data Processing and Peripherals
DPA : Distinguishing Path Attribute
DPC : Defence Planning Committee
DPDG : Diplomatic and Protocol Drafting Group
DPE : Digital Plot Extractor
dpi : dots per inch
DPL : Deputy Project Leader
DPL : Displayed Flight Plan
DPL : Duplicate Plan
DPS : ATM Data Processing System
DPS : Detailed Production Specification
DPS : Distributed Processing System
DPSADD-TF : Data Processing Systems Architecture Description Document Task Force (ATD)
DPSK : Differential Phase Shift Keying

DPT : Depth
DPT : Dynamic Time-based Planning

DR…: Low drifting (followed by DU SA or SN)

DR : Drifting (meteo)
DR : Dead Reckoning
DR : Disaster Recovery
DRA : Defense Research Agency (UK)
DRAM : Dynamic Random Access Memory
DRC : Defence Review Committee
DRC : Dynamic Route Change
DRCP : Data Reduction Computer Program
DRDF : Digital Readout Direction Finder
DRF : Departure Flow Regulation

DRFT : Snowbank(s) caused by wind action

DRG : During
DRMS : Distance Root Mean Square

DRU Data Retrival Unit
DRUG : Dutch Radars Users Group (NL-Eurocontrol)
DRUM : Diagnostic Recorder for Usability Measurement
DS : Data Source

DS : Dust Storm (meteo)
DSA : Director(ate) Safety, Airspace, Airports and Information Services (Eurocontrol, EATM)

DSA : Directory System Agent
DSAP : Destination Service Access Point (RMCDE / RADNET)
DSB : Double Side Band (8.33 User Guide)
DSC : Downstream Clearance
DSCVHF : Digital Selective Calling - Very High Frequency
DSF : Distribution and Switching Facility
DSI : Data Source Interface 
DSI : Denmark Sweden Interface  
DSM : Departure Suspense Message
DSP : Datalink Status Panel
DSP : Digital Signal Processor
DSP : Domain Specific Part

DSPLCD : Displaced

DSPY Display (annunciation on CDU)
DSS : Data Systems Specialist
DSS : Decision Support System
DSS : Direct Subsystem
DST : Decision Support Tools
DST : Direct Support Task
DSU : Data-Source Selector Unit
DSU : Direct Support Unit
DT&E : Development, Test and Evaluation

DTAM : Descend to and maintain
DTE : Data Terminal Equipment (RMCDE)
DTED : Digital Terrain Evaluation Data (militaries ECAC)

DTG : Date Time Group
DTF : Data Link Test Facility (ICAO)

DTG Distance-to-go
DTMF : Dual Tone Multifrequence (code)
DTN : Data Transport Network
DTP : Desk Top Publishing

DTRT : Deteriorate or Deteriorating
DTS : Data Terminal Set
DTS : Data Transmission System
DTU : Data Transmission Unit (VCS)
DTVOR : Doppler Terminal VOR

DTW : Dual Tandem Wheels
DU : Display Unit

DU : Dust (meteo)
DUA : Dedicated User Area
DUA : Directory User Agent
DUAT : Direct User Access Terminal
DUAU : Data Update and Access Unit

DUC : Dense Upper Cloud

DUR : Duration
DVAS : Documentation and Visual Aids Specialist
DVI : Direct Voice Input
DVO : Direct Voice Output
DVOR : Distance VOR
DVOR : Doppler VOR

DVORTAC : Doppler VOR and Tacan
DVP : Development and Verification Platform (part of EGNOS)

DW : Dual Wheels
DWP : Departure Waypoint
DYNAV : Dynamic Route Availability

DZ : Drizzle
DZ : Algeria (ISO countries Codes)




E : East

E : Spain

E/D End-of-Descent

E/O Engine-Out
E+M : signalling
EA : Europe Airsports
EAA : European Aviation Agency
EAC : East Assistant Controller
EACAC : Evolutionary AIR Ground Cooperative ATM Concept
EACG : European ATFM Consultation Group
EACNSISG : EATCHIP Architecture and CNS Infrastructure Sub-Group
EAD SGR : EAD Sub-Group
EAD : Earliest Arrival Date
EAD : European AIS Database
EADCOS : EAD Co-ordination Group
EADI : Electronic Attitude Director Indicator
EADTF : European AIS Database Task Force
EAG : European ATFM Consultation Group and its two Subgroups (Operations and Systems Sub-Group)
EAG : Event Analysis Group
EAIP / EAIP-TF : Electronic Aeronautical Information Publication (Task Force)
EAM : Eurocontrol Airspace Model
EAMG SSG : EAMG Systems Sub-Group
EAMG :  European ATFM Management Group (supervision of the CFMU)
EAN : European ATSO Network
EANPG : European Air Navigation Planning Group (ICAO)
EAP : EATCHIP Alignment Process
EARTS : En-Route Automated Radar Tracking System

EAS Equivalent Airspeed
EAS : EUROCONTROL Advisory Service / Division
EAS : European AIS System
EASA : European Aviation Safety Authority (Agency)
EASG : EASIE ATM Support Group
EASIE : Enhanced Air Traffic Management and Mode S Implementation in Europe
EAT : Expected / Estimated Approach Time
EATCFMU : European Air Traffic Central Flow Management Unit
EATCHIP LO : EATCHIP Liaison Officer
EATCHIP OCD : Operational Concept Document
EATCHIP : European Air Traffic Control Harmonisation and Integration Programme (see EATM)
EATCOS : ECAC TF on the Integration of European ATC Systems
EATF : EATMS Architecture Task Force
EATM : European Air Traffic Management Programme (former EATCHIP)

EATMP : The European Air Traffic Management Programme
EATMS : (Future) European Air Traffic Management System
EATN : (European) Experimental Aeronautical Telecommunication Network 
EAWDG : EATMS Architecture Workshop Drafting Group

EB : Eastbound
EB : Executive Board (of the EUROCONTROL Agency)
EBAA : European Business Aviation Association
EBCDIC : Extended Binary Coded Decimal Interchange Code
EBP : Emergency Bypass Processor 
EC : European Commission
EC : European Community
EC : Executive Controller (also referred to as `Radar Controller')
EC : Eyes closed
ECA : Executive Controller Assistant
ECAC  : European Civil Aviation Conference
ECAC area : European Civil Aviation Conference Area
ECAC Reference Levels : European Civil Aviation Conference Area Reference Levels
ECAC Strategy : European Civil Aviation Conference Strategy
ECAF : ECAC Centralised Airspace Facility
ECAM : Electronic Centralised Aircraft Monitoring (airbone display)
ECARDA : European Coherent Approach to Research and Technological Development for ATM
ECBAG : EATCHIP Cost-Benefit Advisory Group
ECC : EATCHIP Co-ordination Committee
ECC-AIRS : European Co-ordination Centre for Aircraft Incident Reporting Systems (EC)
ECCG : Experimental Centre Consultation Group
eCE : enlarged Committee for Route Charges
ECEF : Earth-Centered-Earth-Fixed

ECET : End of Civil Evening Twilight
ECG : EATCHIP Communication Gateway
ECHO : EATCHIP CNS/ATM Holistic Model Using RM-ODP
ECHQ : Eurocontrol Headquarters
ECI : EAD Client Interface
ECIP : European Convergence and Implementation Plan
ECIPD : Document ECIP
ECIT : EAD Client Interface Terminal
ECM : EATCHIP Co-ordination Meeting
ECM : Electronic Counter Measure / Message
ECM : Executive Control Message
ECM : Extended Callsign Menu
ECMA : European Computer Manufacturers' Association
ECMT : European Conference of Ministers of Transport
eCN : enlarged Commission

ECON Economy (minimum cost speed schedule)
ECP : Engineering Change Proposal
ECP : Expedite Clearance Procedure
ECR : Event Contract Request (ICAO)
ECRSG : EATMS Concept & Requirements Sub-Group
ECRG : Experimental Centre Review Group

ECS Environmental Control System
ECSC : European Conference on Satellite Communications
ECT : European Coordination Team
ECTF : EATMS Concept Task Force
ECU : European Currency Unit
Ed(s) : Editor(s)
ED50 : European Datum 1950 (Geodetic system)
ED70 : European Datum 1970 (Geodetic system)
ED87 : European Datum 1987 (Geodetic system)
EDA : Electro-Dermal Activity measurement
EDAG : European Delay Analysis System Advisory Group
EDAS : European Delay Analysis System
EDAS : European Delay Analysis System
EDB : Environmental Data Base

EDCT : Expect Departure Clearance Time
EDD / TID : EDD / Touch Input Device
EDD : Electronic Data Display
EDDF : Environmental Data Processing and Distribution Function
EDDUS : EDD Update System
EDD-VKL : EDD-controller/planner-controller
EDI : Electronic Data Interchange
EDIFACT : Electrical Data Interface for Administration Commerce and Transport 
EDISOFT : Empresa de Serviços e Desenvolvimento de Software, S.A. (PT)
EDMS : Engineering Data Management System (ODS - MAS)
EDP : Electronic Data Processing
EDP : Environmental Data Processing
EDPD : Environmental Data Processing and Distribution
EDS : Explosives Detection System
EE : Estonia (ISO Country Code)
EEB : European Environmental Bureau

EEC : Electronic Engine Control
EEC : EUROCONTROL Experimental Centre
EEC : European Economic Community
EEC/BSC : Eurocontrol Experimental Centre / Building Steering Committee (decision DG)
EEE : Etudes, Essais and Experimentation
EEG : Electroencephalogram
EEI : Essential Elements of Information
EEPROM : Electrically Erasable Programmable Read-Only Memory 
EES : European Eastern States
EET : Estimated Elapsed Time

EFAS : Electronic Flash Approach Light

EFAS : En Route Flight Advisory Service

EFC : Expect(ed) Further Clearance
EFDFMG : EUROCONTROL Flow Data and Flow Management Group
EFDP : European Flight Data Processing

EFIS : Electronic Flight Instrument System

Eff : Effective from (date)
EFL : Entry Flight Level
EFL : Estimated Flight Level
EFMS : Experimental Flight Management System
EFP : España-France-Portugal Plan (co-operation agreement)
EFPD : Extended Flight Plan Description
EFPM : Extended Flight Plan Message
EFPS : External Front Processing System (PALLAS system)
EFQM : European Foundation for Quality Management
EFR : Extended Flight Rules (FREER)
EFS : Electronic Flight Strip
EFS : Extended Flight Store
EFTA : European Free Trade Association
EG : Egypt (ISO Countries Codes)
EGA : Enhanced Graphics Adapter
EGATCM : Eurocontrol Guild of Air Traffic Controllers - Maastricht
EGATS : EUROCONTROL Guild of Air Traffic Services
EGERIA : Engineering Group for European Integration ATC
EGIP : European Gateway for INO Provision
EGNOS : European Global Navigation Overlay Service (SNA)
EGNOS-EM : European Global Navigation Overlay Service - East Mediterranean

EGPWS : Enhanced Ground Proximity Warning System

EGT Exhaust Gas Temperature
EGU : European Gliding Union
EHA : European Helicopter Association
EHD : Danger Area  (followed by identification) [NL]
EHF : Extremely High Frequencies
EHQ : Eurocontrol Headquarters
EHR : Restricted Area (followed by identification) [NL]
EHSI : Electronic Horizontal Situation Indicator
EHT : Extemely High Tension

EI : Air Lingus (airline)
EIA : Electronic Industries Association
EIB : European, Investment Bank

EICAS Engine Indicating Crew Alerting System
EIF : Extended Interface Function
EIIC : Electronics Installation and Implementation Centre
EIPA : European Institute of Public Administration
EIRP : Effective / Equivalent Isotropic Radiated Power
EIS : Environmental Information Sampling

EIU Electronic Interface Unit
EL : Electro-Luminescent

ELBA : Emergency Location Beacon-Aircraft
EL/KYB : EL Keyboard
ELEV : Elevation (environment)
ELINT : Electronic Intelligence
ELM : Extended Length Message

ELR : Extra Long Range
ELS : Electronic Library Service (System)
ELS : Emergency Landing Strip
ELT : Emergency Locator Transmitter
ELW : Extended Label Window

EM : Emission
EMAS : Environmental Management Audit System (Hamburg Airport)

EMBD : Embedded (cumulonimbus) in a layer
EMC : ElectroMagnetic Compatibility
EMCC : EATM Management Coordination Committee
EMCON : Emission Control

END : Stop-end (related to RVR)
EME : Expert militaire d'Eurocontrol

EMER : Emergency
EMERALD : EMErging and Activities of reLevance to ATM concept Definition (European Commission)

EMERG : Emergency
EMEU : Eurocontrol Military Expert Unit
EMF : Exercise Management Facility (Simulator)
EMG : EAD Management Group
EMG : ElectroMyoGram
EMG : Emergency (ICAO)
EMH : EATCHIP Management Handbook
EMI : Electromagnetic Interference
EMIRA : Eurocontrol Maastricht Information Retriever Application
EMIS : EATCHIP Management Information System
EMM : Extractor Monitoring Message
EMOTION 7 : European Maintenance Of TCAS II Logic Version 7.0 (EMOTION 7)
EMP : ElectroMagnetic Pulse
EMS : EATCHIP Management Support

EMS Emergency Medical Services  
EMS : European Mobile System
EMSO : EATCHIP Management Support Organisation
EMSS : European Mobile Satellite Services
EMT : Eye-Movement tracking
EMTO : ECAC Medium Term Objectives Group (to deal with `Constraints to Growth'
EMU : Extended Memory Unit
EN : Euro Norm (CEE)

ENE : East-North-East
ENG : Engineering / Engine

ENGD : CFMU – Engineering Division
ENHANCE : EuropeaN Harmonised Aircraft Noise Control modelling Environment (NATS-DORA)
ENJJPT : Euro-NATO Joint Jet Pilot Training
ENOC : European Network Operating(tion) Concept
ENPRM : European Notice of Proposed Rule-Making
ENR : En-route (ICAO)
ENRI : Electronic Navigation Research Institute (USA - ADS)

ENRT : En Route
ENV : Environment System 
EO : Executive Objectives (EATMS - CSD)
EO : Eyes Open

EOBD : Estimated Off Block Date
EOBT : Estimated Off Block Time 
EOC : Edge Of Coverage
EOCD : EATMS Operational Concept Document
EODP : EATMS Options Discussion Paper
EOG : ElectroOculoGram
EOIG : EGNOS Operators and Infrastructure Group - the ATS providers in the states formerly known as the IKD States
EOLIA : European Pre-operational Datalink Applications Project
EONS : Eurocontrol Open and Generic Graphic System
EOQ : European Organisation for Quality
EP : Expert Panel
EPAC : EATCHIP Policy and Allocation Committee
EPAC : Eurocontrol Programme Appraisal Committee
EPB : EATCHIP Project Board
EPC : Enhanced Planning and Coordination function (project of MDP phase I)
EPCM : Enhanced Planning Control Message
EPD : EATCHIP Planning Division 
EPG : EASIE Policy Group
EPHOS : European Handbook for Open Systems
EPIC : European Programme for the Implementation of a Common geodetic reference frame (WGS 84)
EPIC : Extended PCM Interface Controller (ACS)
EPM : EATCHIP Planning Method
EPM : Electromagnetic Protection Modification
EPMB : EASIE Programme Management Board

EPR Engine Pressure Ratio
EPR, DGS/EPR : External and Public Relations
EPROM : Erasable-Programmable Read-Only-Memory
EPRT : External Processing Response Time
EPS : Exercise Preparation Suite (Simulator)
EPSU : European Public Service Union
EPT : Estimated Parking Time
EPT : Eurocontrol English language Placement Test
Eqpt : Equipment
EQUATOR : Environment for Qualitative Temporal Reasoning (AI)

EQPT : Equipment
ER  : En-Route
ER TC : En-Route Tactical Controller
ERA : European Regional Airlines Organisation
ERABIS : (Swedish) Route Invoicing System
ERATO : En Route Air Traffic Organiser
ERCG : External Relations Coordination Group
ERCS : EXM Resistant Communications System
ERD : End Routing Domain
ERDF : European Regional Development Fund
ERFA : Conference on the Economics of Route Air Navigation Facilities and Airports (ICAO)

ERIP : EAD Remote Interface Package
ERM : En-Route Metering
ERM : Estimate Revision Message
ERN : Earth Referenced Navigation
ERNP : European Radio Navigation Plan (European Commission)

EROPS : Extended Range Operations by Twin-Engine Aircraft

ERP : Effective Radiated Power
ERP : Event-Related Potential
ERP : Extracted Route Points (FPPS/DECADE)
ER-PC : En-Route Planner Controller

ERR : Error Message
ERS : Early Retirment Scheme
ERS : Extracted Route Sequence
ERSS : Eurocontrol Radar Surveillance Standard
ERT : Estimate Revision Message
ERT : Execution Reference Time
ERV : ECM Resistant Voice

ES : Elementary Sector
ES : Emergency System 
ES : End Service / System
ES : Eurocontrol Standard (Document)
ES : Spain (ISO Country Code)
ESA : Electronically Scanned Array
ESA : European Space Agency (=ASE)

ESE : East-South-East
ESARR : Eurocontrol Safety Regulatory requirements
ESCAPE : EUROCONTROL Simulation Capability And Platform for Experimentation
ESCAT : Emergency Security Control of Air Traffic
ESCO : Executive Support and Coordination Office
ESDF : Environmental Static Data Processing and Distribution Function
ESDI : Enhanced Small-Device Interface
ESF : Essential Support Facilities
ESL : Entry Sequence List
ESME : Enhanced Simulation Modelling Environment
ESP : En-route Spacing (Program)
ESPRIT : European Strategic Programme for Research and Development in Inform.Technology

EST : Estimated
EST : Boundary Estimate Message
EST : Estimate message designator
ESTEC : European Space Technology and Research Centre
ESTEEM : Elaboration of a Strategy for the Transition from EATCHIP phase III to the EATMS
ESUP : Eurocat Support System
ET : (Shuttle) External Tank
ET : Executive Task
ETA : Estimated Time of Arrival / Estimating Arrival
ETD : Estimated Time of Departure
ETE : Estimated Time of Entry
ETFDD : Electronic Tabular Flight Data Display
ETFDM : Electronic Tabular Flight Data Message
ETFMS : Enhanced Tactical Flow Management System
ETG : European GNSS Tripartite Group (European Community, Eurocontrol, European Space Agency)
ETL : Extended Track Label
ETMA : Extended Terminal Manoeuvring Area
ETO : Estimated Time Overhead (significant point)
ETOPS : Extended Range Twin Engined Operations
ETOT : Estimated Take Off Time
ETR : ETSI Technical Report
ETRAS : Easy Transported Radar Analysis System
ETREM : Eurocontrol Technical Requirements Model (EAS)
ETRF : European Terrestrial Reference Frame
ETS : Early Termination of Service
ETSI : European Telecommunications Standardi(sation) Institute

ETX End of Transmission
ETX : Estimated Time of Exit
EU : Electronic Unit
EU : European Union
EU-ACA : European Union Airport Coordinators Association (represent more than 120 airports throughout the European Union)
EUCARF : European Central Altitude Reservation Facility
EUM, EUMED, Eumed : Europe Mediterranean Air navigation Region (ICAO)
EUR ANP : Air Navigation Plan in Europe (ICAO Region)
EUR ATN : European ATN
EUR RAN : European Regional Air Navigation (Meeting)
EUR RASC : Regional AIS System Centre inside the ICAO EUR region
EUR : Euro
EUR : European
EUR : European Region (ICAO)
EURACA : European Air Carrier Assembly
EURAM : European Research in Advanced Materials = BRITE
EURAP : European Regional ATS Packet Switching Network (DAKOS+CBN)
EURATN : European experimental Aeronautical Telecommunications Network / Réseau européen de télécommunications aéronautiques
EURET : European Research for Transport (European Communities) ; Specific Resource and Technological Development Programme in the Field of Transport
EURO : Eurocontrol
EURO/5-States RSG : Eurocontrol/5-States Route Structure Group
EUROCAE : European Organisation for Civil Aviation Equipment manufacturers
EUROCAEDS : European Organisation for Civil Aviation Equipment
EUROCONTROL : European Organisation for the Safety of Air Navigation
EUROSIM : Eurocontrol Simulator at the Institute of Air Navigation Services
EUROSTAT : Statistical Office of the European Communities
EUR-RAN : European Regional Air Navigation

EV : Every
EVAS : EATMS Validation Strategy
EVP : EATM Validation Project (formerly C3T)
EVS : Enhanced Visual System
EVS : Evaluation System

EW : Eurowings (airline)
EWA : Error Warning Area
EWAN : EGNOS Wide Area Network
EWBS : EATCHIP Work Breakdown Structure
EWG : Executive Working Group
EWP : EATCHIP Work Programme
EWP : EATM Work Programme
EWP : Enhanced Working Position
EWPA : EATCHIP Work Programme Adaptation
EWPD : EATCHIP Work Programme Document
EWPD : EATM Work Programme Document
EWS : Early Warning System
EWS : Experimental Workstation Simulator
EWT : EATMS Working Team (CSD)
ex GDR : ex German Democratic Republic
EXC : Executive Controller

EXC : Exept

EXEC Execute

EXER : Exercise(s) or Exercising or to Exercise
EXP : Expected
EXPLT : Extrapolate
EXSPEC : Exercise Specification

EXTD : Extend or Extending
extra EUR RASC : Regional AIS System Centre outside the ICAO EUR region

EXY : Easyjet (airline)




F : Fahrenheit

F : France

F : Fixed
F&CM : Flow And Capacity Management
F/G : Foreground
F18 : Field 18 of Flight Plan

FA Final Approach
FA : Course from a Fix to an Altitude (ARINC 424 Path Terminator)
FAA : Federal Aviation Administration 
FAA : Federal Aviation Authority
FAA-STD-042 : National Airspace System Open System Interconnection Naming and Addressing (ISO Standards for Open Systems Interconnection and Data Communication published by ISO, International Standards Organisation).
FAATC : FAA Test Centre

FAC : Facilities
FAC : Final Approach Course (same as IS)
FAC : Flight Augmentation Computer
FACC : Feature and Attribute Coding Catalogue
FACF : Final Approach Course Fix
FACTOR : Development of Functional Concepts from the EATMS Operational Requirements
FACTS : Future Area Control Tools Support
FADEC : Full Authority Digital Engine Control
FAF : Final Approach Fix
FAI : Fédération Aéronautique Internationale (F)


Failure The inability of a system, subsytem, unit or part to perform within previously specified limits.

FAF Final Approach Fix

FAL : Facilitation of International Air Transport
FAN : False Alarm Normaliser (radar)
FANOMOS : Flight track and Aircraft NOise MOnitoring System (RMCDE)
FANS : Future Air Navigation Systems (ICAO)
FANS-1 : Future Air Navigation Systems 1, an initial operational datalink package for the South Pacific
FANS-A : Future Air Navigation Systems A, an initial operational datalink package for AIRBUS aircraft
FANSTIC : Future ATS and New Systems Impacts on Cockpit

FAP : Final Approuch Point
FAP : Future ATM Profile (simulation Brétigny)

FAR : False Alarm Rate
FAR : Federal Aviation Regulations (federal rules under which flight operations are conducted)

FAR Federal Acquisition Regulation

FARAWAY : Fusion of Radar and ADS Data through two WAY datalink
FAS : Final Approach Segment
FAS : Flight level Allocation System
FASID : Facilities And Services Implementation Document (ICAO)

FAST Final Approach Spacing Tool
FASTER : Future AO-ATM-Airports Synergy Towards Enhanced Operations
FAT : Factory Acceptance Test
FAT : Force Aérienne Tactique
FATAC : French Air Force Tactical Air Command
FATMI : Finnish ATM Integration

FATO : Final Approach and Take-off Area
FATUREC : Federation of Air Transport User Representatives in the EEC
FAWP : Final Approach Waypoint
FAX : Facsimile
FB : FallBack

FBL : Light (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA = light rain)
FBS : Fall-Back System

FBO Fixed Based Operator
FC : Course from a Fix to a Distance (ARINC 424 Path Terminator)
FC : Feeder Controller
FC : Formalised Clearances
FC : Frequency Change

FC : Funnel Cloud (meteo) (tornado or water spout)
FCA : Funtional Configuration Audit (MAS - ODS)
FCB : Frequency Coordinating Body
FCC : Federal Committee for Communications
FCC : Flight Control Computer
FCC : Flow Co-ordination Cell
FCD : Flow Control Decision
FCDS : Frequency Channel and Distribution System
FCE : Flow Control Execution
FCG : Financial Consultation Group (AFG)
FCM : Flight Confirmation Message 
FCNP : Fire Control and Navigation Panel
FCO : Future Concepts (EATCHIP domain)
FCOM : Flight Crew Operating Manual
FCOT : Future Concepts Team
FCR : Flow Control Request
FCS : Frame Check Sequence (RMCDE)

FCST : Forecast

FCT : Friction Coefficient
FCTL : Flow Control

FCU : Flight Control Unit
FD : Course from a Fix to a DME Distance (ARINC 424 Path Terminator)
Fd : Doppler Frequency
FD : Flight Data
FD : Flight Director
FDA : Flight Data Assistant

FDB : Full Data Block

FDAMS Flight Data Acquisition and Management System

FDC Flight Data Company
FDDI : Fiber Distributed Data Interface (LAN - RMCDE / MAS)
FDDI : Fiberoptical Digital Data Interchange
FDE : Flight Data Exchange
FDE-ICD : Flight Data Entry - Interface Control Document
FDFM : Flight Data and Flow Management
FDFMG : Flight Data and Flow Management Group 
FDG : Flight Data Group (MAS)
FDG : Flight plan Data Generator
FDM : Flight Data Message
FDMA : Frequency Division Multiplex Access
FDMAS : Flight Data Management Automated System (It. ATFM)
FDMD : Flight Data Management and Distribution
FDO : Flight Data Operations Division

FDOD : CFMU – Flight Data Operations Division
FDP : Flight Data Processing / Flight-plan Data Processor
FDPD : Flight DATA Processing and Distribution
FDPS : Flight Data Processing System
FDR : Flight Data Recorder (CDB / CFMU)
FDS : Flight Data Section
FDSU : Flight Data Storage Unit
FE : tones injected by the Far End switch
FEAST : First European ATCO Selection Test Package  
FEATS : Future European Air Traffic (Management) Systems (ICAO)
FEC : Forward Error Correction
FED : Fonds européen de développement
FEDER  : Fonds européen de développement régional (= ERDF)
FEP : Front End Processor
FES : Fixed Earth Station

FEW : Few

FF : Fuel Flow
FFA : Functional Failure Analysis 
FFAS : Free Flight Airspace
FFI : Final Factory Inspection (CBN - CNG)
FFM : Frankfurt/Main
FFM : Free Flight Mode
FFTF : Future Functions Task Force (4-States/Eurocontrol)
FFU : Fire Fighting Unit

FG : Fog (meteo)

FGS/C Flight Guidance System/Computer
FHA : Functional Hazard Assessment

FI/P : Flight Inspection Permanent

FI/T : Flight Inspection Tempray

FI : CFMU/MSB – Finance Team
FI : Finland (ISO Country Code)

FI : Iceland Air (airline)

F : Flight Instructor
FIAT : First Installed Article Test
FIB : Forward Information Base
FIC : Flight Information Centre
FIC : Frequency Intercom
FIDS : (Swedish) Flight Information Display System
FIFO : First in, First out

FILTIM : Date and Time Stamp of original Message
FIN : Financial Services
FIN : Finland

FIO : Flight Information Office
FIR : Flight Information Region
FIRST : Flexible Independent Radar Skill Trainer (MAS)
FIS : Flight Information Service

FISA : Automated flight Information Service
FIS-B : Flight Information Service - Broadcast
FISC : Flight Information Services Communications
FISO : Flight Information Service Officer
FIT : Factory Inspection Test
FIT : Flight Integration Task
FIT : Flight Plan Input Terminal
FITAMS : Flight Trials of ATN and Mode S activity
FIW : Flight Input (Information) Workstation 
FIX : Fixpoint,
Position in space usually on aircraft's flight plan
FL : Flight Level
FLAS : Flight Level Allocation Scheme
FLAS : Flight Level Allocation System

FLCH Flight Level Change

FLD : Field

FLG : Flashing

FLIDRAS Flight Data Replay and Analysis System
FLIP : Flight Information Publication
FLIPCY : Flight Plan Consistency
FLO : ATS/ATFM Co-ordination meeting (ICAO)
FLO : Flow meetings
FLOE : Informal ATS / ATFM Co-ordination Meeting - Europe East
FLOEast : Informal Flow control Meeting - Europe East (ICAO/EANPG)
FLOS : Flight Level Orientation Scheme
FLOW : Informal ATS / ATFM Co-ordination Meeting - Europe West
FLOWest : Informal Flow control Meeting - Europe West (ICAO/EANPG)

FLR : Flares (Parachute flares)
FLS : Flight Suspension Message 

FLT : Flight
FLT/PLN : Flight Plan
FLTAB : Flight Level Table

FLTCK : Flight Check

FLUC : Fluctuating or fluctuation or fluctuated
FLTP : Flexible Luxembourg Training Platform

FLW : Follow(s) or following

FLY : Fly or Flying
FM : Course from a Fix to a Manual Termination (ARINC 424 Path Terminator)
FM : Flow Manager

FM : Flight Management
FM : Frequency Management

FM : From

FM…: From (followed by time weather change is forecast to begin)

FMA Flight Mode Annunciator: display on or near the PFDs of the current modes of autoflight system
FMAQ : Flight Management Attitudes Questionnaire
FMC : Flight Management Computer (also FMCS - FMC System)
FMCG : Flow Management Co-ordination Group

FMD : CFMU – Flow Management Division
FMEA : Failure Modes and Effects Analysis
FMECA : Failure Modes, Effects and Criticality Analysis
FMG : Flow Management Group (ICAO)
FMGC : Flight Management and Guidance Computer
FMGS : Flight Management and Guidance System
FMP : Flow Management Planning / Position (CFMU - ECAC States)
FMPG : Flow Management Planning Group
FMS : Flight Management System
FMU : Flight Management Unit
FMU : Flow Management Unit
FN : False Negative

FNA : Final Approach
FNM : Flight Notification Message 
FNPT : Flight and Navigation Procedure Trainer

FO First officer
FOC : Full Operational Capability
FOCA : Federal Office for Civil Aviation (Switzerland)
FOCA : Floor of Controlled Airspace
FOM : Figure of Merit (ICAO - ADS)

FOQA Flight Operations Quality Assurance
FOR-DEC : Facts, Options, Risks and Benefits, Decision, Execution and Check
FOU : Frequency of Use
Four-state BFWG : Four-State Budgetary and Financial working Group
FP 5 : Fifth Framework Programme of the European Community for Research, Technological Development and Demonstration
FP : False Positive
FP : Flight Plan
FP : Framework Programme (of the European Commission)
FPA : False Plot Analysis

FPA Flight Path Angle

FPA Focal Plane Array
FPAP : Flight Path Alignment Point
FPB : Flight Progress Board
FPCP : Flight Path Control Point

FPD : Flight Plan Data
FPDETF, FPRDETF : Flight Plan related Data Exchange Task Force
FPF : Flight Plan Fallback
FPFS : First Planned First Served
FPL : Filed Flight Plan (ICAO format)
FPL : Full-Performance Level  
FPLA : Field Programmable Logic Array

FPLA : CFMU/DEVD - Flight Plan Application Section
FPLMTS : Future Public Land Mobile Telecommunications System
FPM : Feet-per-Minute
FPM : Flight Path Monitor (PATs)
FPM : Flight Position Monitor
FPM : Flight Progress Message
FPP : Flight Plan Processing
FPPS : Flight Plan Processing System
FPPU : Flight Planning and Flight Progress Updating

FPR : Flight Plan Route
FPS : Flight Plan Server  
FPS : Flight Progress Strip
FPS : Functional Performance Specification 
FPT : Flight Plan Terminal
FPWO : Flight Plan Work Station Operator 
FPZ : Flight Path Zone (ODID)

FQIS Fuel Quantity Indicating System
FQR : Formal Qualification Review
FR : France (ISO Country Code)

FR : From

FR : Fuel Remaining
FRA : Failure Reporting and Analysis 
FRA : Free Route Airspace

FRA Flap Retraction Altitude

FRA Federal Railroad Administration
FRB : Failure Review Board  
FREER : Free Route Experimental Encounter Resolution
Freq : Next Sector frequency
FRF : Further Route of Flight
FRG : Federal Republic of Germany

FRH : Fly Runway Heading
FRM : Financial Resources Management Core Team

FRNG : Firing

FRONT : Front (relating to weather)

FRQ : Frequent
FRS : Functional Requirements Specifications 
FRUIT : False Replies from Unsynchronised Interrogator Transmissions ;  Friendly Replies Unsynchronised in Time.

FRZN : Frozen (meteo)
FS : Foot Switch (VCS
FS : Functional Statement (ICAO - ADS)
FSA : First System Activation (message)
FSD TF : Functional Specification Development Task Force (EASIE/MODE S)

FSF Flight Safety Foundation
FSK : Frequency Shift Keying

FSL : Full Stop Landing

FSM : Flight Schedule Monitor.
FSM : Frequency Shift Modulation
FSP : Flight Strip Printer
FSPEC : Field SPECification  : field of variable length, indicating which data fields are present in a record and in which order (see also Record)
FSS : Automated/Flight Service Station

FST : First
ft : Feet
FTC : Fast Time Constant
FTE : Flight Technical Error
FTE : Full Time Employee
FTE : Full Time Equivalent
FTFM : Filed Tactical Flight Model 
FTmn : False Track Length Mean
FTP : File Transfer Protocol
FTprob : False Track Probability
FTS : Fast-Time Simulation System
FTsd : False Track Length Standard Deviation
FTT : Flight Technical Tolerance

FU : Smoke (meteo)
FUA : Flexible Use of Airspace
FUAG (FUSG) : Flexible Use of Airspace Group (sub-group of APT)
FUCOZOC : Fuel Consumption Estimator in a ZOC
FUSG : Flexible Use of Airspace Sub-Group (Sub-Group of ANT)
FUT, FCO : Future Concepts
FVS : Flight Verification System
FWC : Flight Warning Computer
FX : Field Extension Indicator (ASTERIX)
FY : Fiscal Year
FYP : Five Year Programme
FYROM : Former Yugoslav Republic of Macedonia

FZ : Freezing (meteo)

FZDZ : Freezing Drizzle

FZFG : Freezing Fog

FZRA : Freezing Rain




G/A : Ground to Air

G/G : Ground / Ground
G/T : Gain over noise Temperature Ratio

G : Green

G : Gusts (meteo)

GA : Garuda (airline)
GA : General Aviation

GA : Go-Around
GAAP : Generally Accepted Accounting Principles
Ga-As : Gallium-Arsenid
GAAS : Generic Approach for ATM Systems

GAC : General Aviation Centre
GACS : Generic ATN Communication Service
GAF : German Air Force
GAFLO : German Air Force Liaison Officer
GAFO : German Air Force Office
GAFOR : General Aviation Forecast (Meteo)
GAIT : Ground-Based Augmentation and Integrity Technique
GAME : GEADGE/ADKAR Message Exchange

GAMET : Area forecast for low-level operations

GAR : Go-Around
GARTEUR : Group for Aeronautical Research and Technology in Europe
GASC : Global Aviation Satellite Communications System
GASR : Group of AGA Safety Regulators (AOT list)
GAT : General Air Traffic or Terminal
GATE : Group of ATM in the Eastern Part of the ICAO EUR Region, including Middle Asia
GB : United Kingdom (ISO Countries Codes)
GBA : Geostationary Broadcast Area
GBAS : Ground Based Augmentation System
GBCC : Ground Based Control Complex
GC : Graphics Controller
GC : Ground Control/Controller
GCA : German Cockpit Association
GCA : Government Quality Assurance
GCA : Ground Controlled Approach
GCAS : Ground-based Collision Avoidance System
GCE : General Certificate of Education
GCL : Graphical Information Category Cursor Line (EAS)
GCS : Ground Control Segment
GCSE : Generate Certificate of Secondary Education
GCST : Group for Coordination of STAR (Studies, Tests and Applied Research)
GCTA : Gestion des Courants de Trafic Aérien (=ATFM)
GCWP : Generic Controller Working Position
GDCA : General Directorate for Civil Aviation (SP)
GDCE : Ground Data Circuit Terminating Equipment
GDLP : Ground Data Link Processor (the Mode S subnetwork function within the ground system that implements the OSI network layer protocols)
GDM : Graphical Information Category Dynamic Maps
GDOP : Geometric Dilution of Precision
GDP : Diplomatic and Protocol Drafting Group
GDP : General Data Processor
GDP : Gross Domestic Product

GDP : Ground Delay Program
GE : Georgia (ISO Countries Codes)
GEADGE : German Air Defense Ground Environment
GEMS : Generic Error-Modelling System
GEN : General
GENOFIC : General North Sea Flight Information Centre

GEO : Geographic or True
GEO : Geostationary Satellite Orbit
GEOREF : Geographical Reference
GEOSTAR : Multipurpose Satellite System Using Fixed Orbit Satellites 
GERAC : EANGP WG on Coordination of the Implement & Operation of an Improved EUR AFTN/AFS
GERAC : Group on European Regional AFTN/AFS Implementation and Operation Coordination
GES : Ground Earth Station (ICAO - ADS)
GETALIS : Sistema de Gestão de Tráfego Aéreo de Lisboa (PT) / Future Lisboa Air Traffic Management System

GF : Gulf Air (airline)
GFDI : GNSS Fault Detection and Isolation
GFM : Graphical Information Category Fixec Maps
GGCS : Ground/Ground Communication System (ICAO)
GGDC : Ground/Ground Data Communication
GGDC-SG/GGDCSG : Ground/Ground Data Communications Sub-Group
GGVC-SG/GVCSG : Ground/Ground Voice Communications Sub-Group
GHMI : Ground Human-Machine Interface
GHz : Gigahertz
GIB : Global Navigation Satellite System Integrity Broadcast
GIB : GPS Integrity Broadcast
GIC : Geostationary Integrity Channel
GIC : GNSS Integrity Channel
GICB : Ground Initiated Comm B Protocol (Mode S)
GIPS : Giga Instructions Per Second
GIPS : General Image Processing System
GIPS : Global Initial Positioning System
GIS : Geographical Information System

GLD : Glider
GLONASS : Global Orbiting Navigation Satellite System (USSR)
GLOSS : Global Sea Level Observing System
GLSU : GPS Landing System Unit
GM : Guidance Material
GMC : Ground Movement control
GMD : General Meeting of Directors

GMS : Global Positioning System Monitoring System
GMS : Ground Monitoring System
GMS : Ground Movement Surveillance
GMT : Greenwich Mean Time. See UTC
GMU : GPS (Height) Monitoring Unit
GNC : Global NAVCOM (IATA/ICAO Conference)
GND : Ground Control service / facility
GND : Ground Level

GNDCK : Ground Check
GNE : Gross Navigational Error
GNLS : GNSS Navigation and Landing System
GNLU : GNSS Navigation and Landing Unit
GNP : Gross National Product
GNSS : Global Navigation Satellite System
GNSSP : Global Navigation Satellite System Panel (ICAO)
GOMS : Goals, Operators, Methods, Selection (rules)
GOTV : GNSS Operational Test and Validaton

GOVT : Government
GP : Gilde Path
GPIWG : Glide Path Intercept Waypoint
GPS : (Satellite Navigation and) Global Positioning System / Geographical Paging System, a technique for deriving location from space-based assets.
GPS : Geographical (Paging) Positioning System
GPSSU : GPS Sensor Unit
GPTP : Guided Part-Task Practice
GPV : GNSS Performance Validation
GPWS : Ground Proximity Warning System (warns of inadequate separation from ground and excessive sink rate close to ground)

GR : Hail >5mm (meteo)
GR : Greece (ISO Country Code)
GRACE : Geographical Association and Classification of Events

GRADU : Gradual or Gradually

GRAF Ground Replay and Analysis Facility
GRADE : Ground Return Area Digital Eliminator
GRANAS : Global Radio Navigation System

GRASS : Grass landing area

GRIB : Processed meteorological data in the form of grid point values (aeronautical meteorological code)
GRIGRI : Gestures, Recognition on Interactive Graphical radar Images
GROBI : Graphical Object Interface
GROUP SIMUL : Group Simulation

GRP Geographical Reference Points

GRVL : Gravel

GS : Small hail or snow pellets (meteo)
GS : Glideslope
GS : Graphical Station
GS : Ground Speed

GS : Gound Stop
GSA : Guided Skill Acquisition
GSE : Ground Support Equipment

GSFC Goddard Space Flight Center  
GSIMUL : Guided Simulation
GSM : Global System for Mobile Communications
GSM : Graphical Information Category Scale Marking
GSNA : Ground-Supported Navigation Advisory
GSO : Geosynchronous Orbit
GSO : Group of Senior Officials
GT : Ground Transmitter
GT2 : Ghost Track rate (radar standard)
GTB : General Tool Box
GTC : Gain Time Control
GTE : Groupe tripartite européen
GtG programme : Gate-to-Gate programme
GTID : Group training - Instructor-dependent
GTIS : Ground-based Traffic Information System
GTMD : Group Training - Material-dependent
GTO : Geosynchronous Transfer Orbit
GTP : Groupe de travail "Pensions" / Pensions Working Group (= PWG)
GTr : Ghost Track Rate
GTRC : General Technical Requirements and Conditions
GTS : Global Telecommunications System
GTVS : Ground based Transponder performance Verification System (SCT)
GUI : Graphical User Interface
GUIDE : General User Interface Device

GW Gross Weight
GWL : Graphical Information Category Weather Lines




H24 : Continuous Day and Night Service

: Hungary
H, h : Hour
H/M/L : High/Medium/Low (ATC Complexity)
HA : Holding to an Altitude (ARINC 424 Path Terminator)

HAA : Height Above Airport

HAC Hughes Aircraft Co.  
HAD : Human Aspects Development
HADAMARD : Multi-radar processing written in ADA

HAI Helicopter Association International
HALO : High Altitude, Low Opening
HALS / DTOP : High Approach Landing System / Displaced Threshold Operations
HAMMER : High-level All-purpose Monitoring and Management Equipment for RADNET

HAPI : Helicopter approach path indicator
HAT : Height Above Touchdown
HATR : Hazardous Air Traffic Report
HAW : Horizontal Aid Window (ODID)

HBARO Barometric Altitude

HBN : Hazard Beacon
HBS : Hotline Back-up System
HCA : Human-Centred Automation
HCAA : Hellenic Civil Aviation Authority
HCD : Hard Copy Device
HCI : Human Computer Interface
HCP : Hard Copy Printer

HD : Air Holland (airline)
HD : Harmonisation Documents
HDB : Historical Data Base 
HDBK : Handbook
HDD : Head Down Display

HDF : High frequency direction-finding station
HDG : Heading

HDG SEL Heading Select
HDLC : High Level Data Link Communication
HDLC : High Level Data Link Control 
HDOP : Horizontal Dilution of Precision


HE Altitude Error
HED : Heading
HEIDI : Harmonisation of European Incident Definitions Initiative for ATM (SQS)

HEL : Helicopter
HEL : High Energy Laser

HELI : Heliport
HELLANET : Hellenic aeronautical Network
HEO : Highly inclined Elliptical Orbit
HERA : Human Error in ATM  
HERAS : Hellenic Radar System
HERMES : Harmonised En-Route Metering and Spacing (Sequencing)
hex : hexadecimal
HF : High Frequency
HF : Holding to a Fix (ARINC 424 Path Terminator)
HF : Human Factors (Modules = HRT)
HFDL : High Frequency Data Link
HFIAI : Human Factors in Incident and Accident Investigation (HRT)
HFS : Human Factors Studies
HFSG : Human Factors Study Group (ICAO)
HFTE : Human Factors Testing and Evaluating
HFX : Holding Fix
Hg : Mercury

HGT : Height or Height Above
HHmm : Hours and minutes
HHMMSS : hour-hour / minute-minute / second-second

Hl : High
HI FI SIM : High-Fidelity Simulator
HIDE : Harmonised, Integrated Development Environment
HIFA : Human Integration in Future ATM Systems
HIPERLAN : High Performance Local Area Network
HIPS : Highly Interactive Problem Solver

HIRL : High Intensity Runway Lights
HIRO : High Intensity Runway Operations

HIRS High-Resolution Infrared Sounder
HIRTA : High Intensity Radio Transmission Area
HIT : Hardware Integration Test (MAS/DFS - ODS)
HIT : Hughes Improved Terminal

HIWAS : Hazardous Inflight Weather Advisory Service

HJ : Sinrise to Sunset
HLD : Hold List
HLDC : High Level Data Link Control

HLDG : Holding
HLLC : High Level Link Layer Control
HLT : Heavy Load Threshold
HM : Holding to a Manual Termination (ARINC 424 Path Terminator)
HMATTF : Handling of Military Air Traffic Task Force
HMD : Horizontal Miss Distance (filter) (TCAS/ACAS)
HMI : Human Machine Interface or interaction
HMR : Helicopter Main Routes
HMT : Hand Microphone Telephones
HMU : Height Monitoring Unit (in connection with RVSM)
HMZ : Slovenian National Hydrometeorological Institute

HN : Sunset to Sunrise
HND : Hand over keyboard button
HNS : Host Nation Support
HNSE : Horizontal Navigation System Error

HO : Service available to meet operational requirements
HOA : Hand-off Acceptance
H-OFF-A : Hand-Off Accept
H-OFF-P : Hand-Off Propose
HOL : High Order Language

HOL : Holiday
HOLD : Hold(ing)
HOOD : Hierarchical Object Oriented Design
HOP : Hand-off Proposal
HOP : Harmonisation of Operational Procedures (AT, CH, DE)
Hor : Horizontal
HOSP : Hospital Flight/Aircraft

Host Computer Facility located at the ARTCC which operates user application software, as well as certain peer network layer protocols required to communicate with adjacent ATN routers.

Host Processor "End system" as defined by ISO that includes the OSI upper layer protocols (i.e., transport layer and above) and application processes
Hp / hPa : hectopascal
HP : High Precision

HP : Holding Pattern
HP : Horse-Power
HPA : High Power Amplifier
HPC : Hughes Programming Centre (NPC)
HPD : Horizontal Polar Diagram

HPRES Pressure Altitude
HPRT : HMI Preview Response Time
HPZ : Helicopter Protection Zone
HQ : Headquarters (EUROCONTROL Agency)
HR : Croatia, Republic of Croatia
(ISO Country Code)

HR : Hour
HR : Human Resources
HRA : Human Reliability Assessment / Analysis
HRD : Human Resources Directorate
HRFG : Human Resources Framework Group
HRI : Human resources International (Israël)
HRIS : Human Resources Information System
HRM : Human Resources Management
HRP : Human Resources Planning and Corporate Services
HRPTSG : Human Resource Planning and Training Study Group (ICAO)
HRS : ATM Human Resources Management Programme (EATM)
hrs : hours
HRSC : Human Resources Steering Committee (Training Programme Ab Initio, CC)
HRT : Human Resources Team
HRV : Heart-Rate Variability

HS : Service available during hours of scheduled operations
HS : Headset
HSCT : High-speed Civil Transport
HS-DTS : High Speed Data Transmission System

HSI Horizontal Situation Indicator
HSM : High Speed Modem
HST : Hypersonic Transport
HTA : Hermes Training Aircraft
HTA : Hierarchical Task Analysis
HTD : History Trial Dots 
HTI : Human Technology Integration
HTZ : Helicopter Traffic Zone
HU : Hungary, Republic of Hungary (ISO Country Code)
HUD : Head up Display
HUM RES : Human Resources

HUM : Humanitarian
HUM : Human Resources (Domain/Unit)
HUMR : Human Resources

HURCN : Hurricane

HV : Transavia (airline)

HVDF : High and very high frequency direction finding stations at the same location

HVY : Heavy

HVY : Heavy (used to indicate the intensity of weather phenomena)
HW, h/w : Hardware
HWCI : Hardware Configuration Item
HWCI : Hardware Configuration Item (MAS/DFS - ODS)
HWG : Harmonisation Working Group
HWP : Holding Waypoint

HX : No Specific working hours
Hz : Hertz (cycle per second)

HZ : Haze (meteo)




I : Italy
I and Q Channels : In-phase and Quadrature channels
I(Fd) : MTI Improvement Factor
I/A : Incident Analysis
I/O : Input / Output
I/R : Interrogator/Responsor
I²SLS : Improved Interrogation Side Lobe Suppression
IA : Indirect Access

IA Inspection Authorization
IA : International Alphabet
IA/CC : Indirect Access/Common Control
IA-5 : International Alphabet Number 5
IAAE : International Association of Airport Executives

IAC : Instrument Approach Chart

IAC : Integrated Avionics Computer
IACA : International Air Carrier Association
IACH : Individual ATC Flight Plan Changes 
IACS : INTERGRAPH Aeronautical Charting System
IACSP : International Aeronautical Communications Service Providers
IAEA : International Atomic Energy Agency
IAF : Initial Approach Fix
IAFP : Individual ATC Flight Plan Proposal
IAG : Interim Airport Group
IAG : International Association of Geodesy
IAIP : Integrated Aeronautical Information Package 
IAL : Instrument Approach and Landing (Chart)
IAL : International Air-radio Limited (UK)
IAM : Institute of Aviation Medicine
IAMP : Initial Approach Waypoint
IANS : Institute of Air Navigation Services (Luxembourg)
IANSSC : IANS Steering Committee
IAO : In and out of clouds

IAOA : Indicated Angle-of-Attack
IAOPA : International Council of Aircraft Owner and Pilot Associations

IAR : Intersection of Air Routes
IAR : Instrument Autonomous Rules
IAR, IARTF : Institutional Arrangements and Requirements Task Force
IARR : IFPS ARR Message – Individual Arrival Message
IAS : Indicated Air Speed
IATA : International Air Transport Association
IATTF : IFPS Acceptance Test Task Force
IAW : In accordance with
IAWP : Initial Approach Waypoint

IB : Iberia (airline)
IB : Information (display) Button
IBAA : International Business Aviation Association
IBAC : International Business Aviation Council
IBAP : Industry Based Prototype
IBILS : Integrity Beacon Landing System  

IBN : Identification Beacon
IBP : Industry-Based Pre-operational Platform and Validation
IBRD : International Bank for Reconstruction and Development (= BIRD)

IC : (very small) Ice Crystals (meteo) (also know as Diamond dust)
IC : Integrated Circuit
IC : Intercom
ICAA : International Civil Airport Association

ICAAS : Integrated Control in Avionics for Air Superiority
ICAO : International Civil Aviation Organisation

ICARD : ICAO Codes and Route Designator System
ICB : International Competitive Bidding
ICBM : Intercontinental Ballistice Missile
ICCS : Integrated Communication Control System
ICCT : Internal Communications Core Team
ICCU : Intercomputer Communications Unit
ICD : Interface Control Document

ICE : Icing

ICET : IATA Capacity Enhancement Team
ICHG : IFPS Change Message
ICIP : Inital CIP (APT)
ICM : Interline Communications Manual
ICNI : Integrated Communications, Navigation and Identification
ICNL : IFPS Cancellation Message
ICNL : Individual Cancel 
ICO : Intermediate Circular Orbit
ICP : Interactive Control Panel
ICP : Internal Clarification Project
ICR : Integrated Cancellation Ratio
ICR : Interactive Conflict Resolution
ICWG : Interface Control Working Group
ICWS : Integrated Control Work Station
ID : Identification (ICAO)
ID : Information Display
IDA : Indirect Access (VCS)
IDA : Initial Distribution Area
IDB : Integrated Database (DBE + DBC)
I-DCTS : Interim Digital (Data) Communications Terminal System

IDENT Identification Identify, Identifier
IDHS : Intelligence Data Handling System
IDMS : Integrated Database Management System
IDP : Initial Domain Part
IDRP : Inter Domain Routing Protocol
IDS : Information Display System
IE : Ireland
(ISO Country Code)
IEC : International Electrotechnical Commission/Committee
IEEE : Institute of Electrical and Electronic Engineers (US)
IEP : Information Exchange Programme

IEPR Integrated Engine Pressure Ratio
IES : Interface Editor System
IETF : Internal EATMS Task Force
IF : Initial Fix (ARINC 424 Path Terminator)
IF : Intermediate (approach) Fix
IF : Intermediate Frequency
IFA : Image Frequency Attenuation
IFALPA : International Federation of Airline Pilots Association
IFATCA : International Federation of Air Traffic Controllers Associations
IFATSEA : International Federation of Air Traffic Safety Electronic Associations
IFD : Initial Functional Description / EASIE
IFDS : Interactive Flight Data System

IFE : In-Flight Entertainment

IFIM : International Flight Information Manual
IFF : Identification Friend or Foe
IFFITAF : IFPS-DBE Functional Interface System Task-Force
IFFN : Identification Friend, Foe or Neutral
IFG-NME WG : Implementation Facilitation Group of the National Management Experts Working Group
IFL : Intermediate Flight Level
IFLIPS : Integrated Flight Prediction System

IFOG : Interferometric Fiber Optic Gyro (see FOG)
IFOR : Implementation Forces (UN, NATO)

IFP : Keyword from IFPS used in FIELD 18 to provide a warning
IFPD : Individual Flight Plan Data
IFPL : IFPS Filed Flight Plan
IFPL : Individual Flight Plan Message

IFPO : IFPS Workstation Operaror
IFPPS : Integrated Flight Plan Processing System
IFPRU : IFPS Responsible Unit
IFPS : Integrated Initial Flight Plan Processing System  

IFPU1/RPL : CFMU/FDOD - IFPS Unit - Haren Brussels (Belgium)
IFPU2 : Integrated initial Flight Plan Processing System (Unit 2) CFMU/FDOD - IFPS Unit - Brétigny-sur-Orge (France)
IFR : Instrument Flight Rules
IFRB : International Frequency Registration Board
IFTO : International Federation of Tour Operators

IG : Meridiana (airline)
IGA : International General Aviation
IGCN : Independent Ground Communications Network

IGFET Insulated Gate Field Effect Transistor
IGP : Ionospheric Grid Point
IGS : International GPS Reference Network
II : Interrogator Identity
IIMSES : Initial Implementation of Mode S Enhanced Surveillance (a common project UK, France, Germany, Benelux, including POEMS)
IIS : Internal Information System
IISLS : Improved Interrogation Side Lobe Suppression
IKBS : Intelligent Knowledge Based System
IKD States : In Kind Delivery States (France, Germany, Italy, Spain, UK, represented by their ATS providers: DNA, DFS, ENAV, AENA, NATS)
IL : Israël (ISO Countries codes)
ILO : International Labour Organisation / Organisation Internationale du Travail (=OIT)
ILS : Instrument Landing System
ILS : Integrated Logistic Support
ILSP : Integrated Logistic Support Program

IM : Inner Marker
IM : Information Management
IMA : Integrated Modular Avionics
(see AIMS )
IMAL : Integrity Monitoring Alarm Limit
IMAWP : Initial Missed Approach Waypoint
IMC : Instrument Meteorological Conditions
IMF : International Monetary Fund

IMG : Immigration
IMM : Interacting Multiple Models : a generally applicable algorithm of track state estimation
IMO : International Maritime Organisation / Organisation maritime Internationale (= OMI)
IMP : Implementation Services
IMPACT : Informal Management Panel for ATC Training
IMPACT : Information Market Policy Actions
IMPACT : Innovative Methodology for the Projection of ATM Concepts onto the Training of ATCOs
IMPACT : Methods and tools to assess IMPACT on future ATM systems
Impl : Implementation

IMPR : Improve or Improving

IMT : Immediate or Immediately
IMTEG : ILS/MLS Transition EUR Group 
IMUX : Input MUltipleXer

IN : Inch, Inches

INA : Initial Approach

INBD : Inbound

INC : In Cloud(s)
InCAS : Interactive Collision Avoidance Simulator

INCERFA : Uncertainty Phase

INDEFLY : Indefinitely
IND SIMUL : Individual Simulation
Ind : Industry

INFO : Information
INFR-C : Infrastructure Creation

in.hg. inches of mercury
INI : Initial Approach Controller

INIT Initialization
INM : Integrated Noise Model (software developed by the US FAA, manufacturer: Aerospatiale Matra Airbus)
INMARSAT : International Mobile Satellite Organisation 
INO : International NOTAM Operation

INOP : Inoperative

INP : If Not Possible

INPR : In Progress

INR Image Navigation and Registration

Ins : Inches
INS : Inertial Navigation System
INST : Installation

INSTL : Install or Installed or Installation
INSTAR : Institutional Arrangements for European Air Traffic Management
INSTILUX : Eurocontrol Institute of Air Navigation Services (LU)

INSTR : Insturment
Int : International

INT : Interesection

INTC Intercept
INTELSAT : International Telecommunications Satellite Organisation
Interactive : Interactive training
INTERCAUTRA : Internal CAUTRA protocol
INTL : International
INTNET : Integration Network (for flight data exchange)

INTRG : Interrogator

INTRP : Interrupt or Interruption or Interrupted

Intruder : Aircraft against which TCAS issues an advisory

INTSF : Intensify or Intensifying

INTST : Intensity
INU : Inertial Navigation Unit
INV : Innovative Studies and Technological Assessment (ARDEP)
INV : Inverse / Inverted
INWP : Intermediate Waypoint
IO, I/O : Interoperability - Input / Output
IOATF : IFPS Operational Advisory Task Force

IOBD : Initial Off-Block Date

IOBT : Initial Off-Block Time
IOC : Initial Operational Capability
IOCD : Initial Operational Concept Document
IOCP : Internal Operational Clarification Project
IOD : Issue of Data
ION : Institute of Navigation
IOP : Input / Output Processor (RMCDE)
IOR : Indian Ocean Region (ICAO)
IOR : INMARSAT Indian Ocean Region
IOSS : Input Output Sub System
IP : Information Button (mouse)
IP : Information Paper
IP : Internetwork Protocol
IPAG : Intellectual Property Advisory Group (Policy Guidelines for Intellectual Property Rights)
IPAS : Integrated Preparation and Analysis System
IPB : Inner Performance Boundary (Tunnel Concept)
IPC : Intermittent Positive Control
IPCC : Intergovernmental Panel for Climate Change
IPG : Integration Project Group
IPL : Initial Programme Loading
IPL : Intermediate Flight Plan
IPR : Intellectual Property Rights
IPRT : Internal Processing Response Time
IPS's : Intellectual Proprietary Rights
IPSE : Integrated Programming Support Environment
IPSky : Internet Technology in the Sky
IPT : Internal Processing Time

IPT Integrated Product Team
IPv6 : Internet protocol version 6
IQ : Intelligence Quotient
IQ : Iraq (ISO countries codes)

IR : Ice on Runway

IR : Infrared
IR : Integrated Receiver
IR : Iran (ISO countries codes)

IR : Iran Airlines (airline)
IRAS : Interactive Radar Analysis System
IREN : Incident Reporting European Network
IRF : Incident Report Form (DECADE)
IRF : Interrogation Repetition Frequency (radar standard)
IRIG : (clock)
IRL : Ireland
IRMA : Intermediate Redesigned MCC Architecture (ESCO/DECADE)
IROI : Instantaneous Return on Investment
IRPL : Internal Repetitive Flight Plan
IRR : Internal Rate of Return
IRS : Inertial Reference System
IRS : Interface Requirements Specification
IRS : Intermediate Route Sequence (FPPS/DECADE)
IRT : Interrogation Repetition Time
IRU : Inertial Reference Unit
– part or IRS
IRVR : Instrument Runway Visual Range
IS : Iceland (ISO Country Code)
IS : Interface Specification
IS : Intermediate System

ISA : Inertial Sensor Assembly - part of IRS
ISA : Innovative Slot Allocation
ISA : Instantaneous Self-Assessment
ISA : International Standard Atmosphere

ISB : Independent Sideband
ISDN : Integrated Services (switched) Digital Network (=RNIS)

ISDU : Inertial System Display Unit
IS-ES : Intermediate System - End System
ISL : Intermediate Supplementary Flight Level
ISLS : Interrogation Side Lobe Suppression
ISO 10737 : Transport Layer Management (Standards For Open Systems Interconnection And Data Communication Published by ISO)
ISO 7498-3 : Basic Reference Model Part 3 : Naming And Addressing (Standards For Oven Systems Interconnection And Data Communication Published By (ISO)
ISO 8072 : Transport Service Definition (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8073 AD 1 : Connection-Oriented Transport Protocol Addendum 2 : Class Four Operation Over Connectionless Network Service (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8073 : Connection-Oriented Transport Protocol Specification (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8208 : International Organisation for Standardisation X.25 Packet Level Protocol for Data Terminal Equipment Document.
ISO 8326 : Basic Connection-Oriented Session Protocol Specification (Standards For Open System Interconnection And Data Communication Published By ISO)
ISO 8327 : Basic Connection-Oriented Session Protocol Specification (Standards For Open Systems Interconnection And Data Communication Published By IS0)
ISO 8348 AD 1 : Network Service Definition, Addendum 1 : Connectionless Mode Transmission (Standards For Oven Systems Interconnection And Data Communication Published By ISO)
ISO 8348 : Network Service Definition (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8473 : Protocol For Providing The Connectionless-Mode Network Service (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8649 : Service Definition For The Association Control Service Element (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8650 : Protocol Specification For The Association Control Service Element (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8822 : Connection-Oriented Service Definition (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8823 : Connection-Oriented Presentation Protocol (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 8878 : International Organisation For Standard Use Of X25 To Provide OSI (Open Systems Interconnection) Connection Mode Network Services (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 9000 : International Standards For Quality Management, 1990
ISO 9072-1 : Remote Operations - Part 1 : Model. Notation And Service Definition (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 9072-2 : Remote Operations - Part 2 : Protocol Specification Version (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 9545 : Protocol For Providing The Connectionless-Mode Network Service (Standards For Oven Systems Interconnection And Data Communication Published By ISO)
ISO 9595 : Common Management Information Service Definition (Standards For Open Systems Interconnection And Data Communication Published By ISO)
ISO 9596 : Management Information Protocol - Part 1 : Specification (Standards For Oven Systems Interconnection And Data Communication Published By ISO)
ISO : International Standards Organisation / Organisation internationale de normalisation

ISOL : Isolated
OSI : Open System Interconnexion
ISPACG : Informal South Pacific ATS Co-ordination Group
ISQMS : Integrated Safety and Quality Management System (Safety Domain)
ISR : Independent Standby Radio
ISS : Implementation Support Services ; Implementation Support to States  
ISS : Indirect sub-System
ISSS : Initial Sector Suite System (FAA)
IST : Indirect Support Task
IT : Information Technology
IT : Italy (ISO Country Code)
ITA : Integrated Task Analysis (of ATCOs)
ITA : International Telegraph Alphabet
ITA-2 : International Telegraph Alphabet Number 2
ITAEG : Information Technology Advisory Expert Group (Standardisation, EPD - CEN/CENELEC/ETSI)
ITAM : Integrated Task Analysis Methodology
ITF : International Transport Workers Federation
ITI : Italian Interface
ITID : Individual Training- Instructor-dependent
ITIRS : International Terrestrial Reference System
ITM : Intermediate Approach controller
ITMD : Individual Training - Material-dependent
ITR : International Transit Route
ITSTC : Information Technologie Steering Committee
ITT : Invitation Property Rights
ITU WARC-95 : International Telecommunication Union World Radio Conference
ITU : International Telecommunications Union
ITU-T : International Telecommunications Union - Telephone
IUCM : IFPS Unit Configuration Manager
IVR : Immersive Virtual Reality

IVSI : Instantaneous Vertical Speed Indicator
IVSN : Initial Voice Switched Network
IWGE : International Working Group on (air) Exercises
IWP : Intermediate Waypoint




JAA : Joint Aviation Authority (consists of 29 ECAC National Aviation Authorities)
JAA AMC : JAA Acceptable Means of Compliance
JAA OPS : Joint Aviation Authorities Operations Committee
JAAB/JAA-B : Joint Boards
JAAC/JAA CE : JAA Committee
JAARC : JAA Research Committee
JAC : Joint Airmiss Committee (UK)
JACC : Joint Area Control Centre

JAL : Japan Air Lines
JAMC : Joint Airspace Management Cell (UK)
JAR : Joint Aviation Requirements

JAR  :Joint Airworthiness Regulations

JAR : Joint Airworthiness Requirement
JAR-OPS : Joint Airworthiness Requirements Operations

JATO Jet Assisted Takeoff
JD TF : Job Description Task Force
JIT : Joint Implementation Team (chaired by Eurocontrol) (ESCO) MADAP/KARLDAP

JL : Japan Air Lines (airline)
JMCT : Job Management Consultative Team [job analysis]
JOINT : Joint Operational Incidents Training
JOT : Joint Operational Team (ESCO)

JP : Japan (ISO Country Code)
JPDA : Joint Probabilistic Data Association
JPEG : Joint Photographic Expert Group
JSP : Joint Services Publication

JSRA Joint Sponsored Research Agreement
JST : Joy Stick
JTIDS : Joint Tactical Information Distribution System

JTST : Jet Stream

JU : JAT – Yugoslavian Airlines (airline)
JURG : Joint Users' Requirements Group (Eurocontrol Representative' in the IATA/AEA )




K : Thousend

K, k : Symbol for kilo (103)
KAR : Karlsruhe
KARLDAP : Karlsruhe Automatic Data Processing and Display System
KB : Kilo Byte
Kbps : Kilobits per second
KBS : Knowledge-Based System

KCAS : Calibrated Airspeed expressed in Knots
KDS : Keyboard Display System (Station)

KE : Kenya (ISO Country Code)

KE : Korean Airlines (airline)
KECU : Thousands of European Currency Units
KfV : Kuratorium für Verkehrssicherheit (AT) / The Austrian Traffic Safety Board

KG : Kilogram
Khz : KiloHertz
KIAS : Knots Indicated Air Speed
KIDS : Karlsruhe Interim DCTS
KIS : Keyboard Input Station

KL : KLM – KLM Cityhopper (airline)
KLDAP : KARLDAP + Langen (D)

KLM : Royal Dutch Airlines
KLOC : thousand lines of code
km, KM : kilometer

KM : Air Malta (airline)
Km/h ,KMH : kiliometres per hour
KNMI : Koninklijk Nederlands Meteorologisch Instituut (NL) / Royal Netherlands Meteorology Institut
KOX : Karlsruhe Operational Exchange

kPa : KiloPascal
KPA : Key Performance Area (PRC)
KPI : Key Performance Indicator
KPT : Karlsruhe Planning Team
KR 20 : A measure of the internal consistency, or homogeneity, or scalability, of a test material (Ferguson, 1976).
KR : Knowledge of Result
KSA : Knowledge, Skills, Abilities
KSAO : Knowledge, Skills, Abilities, and Other personal requirements
KT/KTS : knots (i.e. 1 NM/hour)
KTD : Keyboard Tabulator Display

KU : Kuwait Airways (airline)
KUAC : Karlsruhe Upper Aispace Control Centre
Kurtosis : A term which refers to the flatness or peakedness of one distribution in relation to another (Ferguson, 1976).
KW, kW : Kilowatt
KYB : Keyboar

KZ : Nippon Cargo Airlines (airline)




l : Liter

L : Left (also: runway identification)

L : Locator
L : Luxembourg
L : Tones injected by the local switch
L/T : Long-Term
LA : LAN Adapter
LA : Local Action

LAA : Local Airport Advisory
LAA : Local Area Argumentation

LAADR : Low Altitude Airway Departure Route
LAAS : Local Area Augmentation System
LACK : Logical Acknowledgement
LACK : The positive logical response message used for air/ground data communications, as defined within the ICAO Manual for ATS Data Link Applications
LAD : Look Ahead Display
LADGNSS : Local Area Differential GNSS
LADGPS : Local Area Differential Global Positioning System
LAF : Local Adaptation Functions

LAHSO : Land and Hold Short Operations
LAM : Ljubljana ATC Data Processing System
LAM : Logical Acknowledgement Message

LAM : The positive logical response message used for ground/ground data communications, as defined within the Eurocontrol Standard for On-Line Data Interchange

LAMPS : Long Term ATCO Manpower Planning Simulation

LAN : Inland
LAN : Local Area Network

LANDA : Logistics and Administration
LANSU : Local Air Navigation Service Unit (DFS)
LAP-B : Link Access Procedure (Protocol type B)
LAR/LRR : Long Range Radar
LARS : Lower Airspace Radar Service
LAS : Last Assigned Landing Slot
LAS : Lower Airspace Sector
LASER : Light Amplification by Stimulated Emission of Radiation
LASKA : Learning And Skills Acquisition
LAT : Latitude
LATC : Local Air Traffic Control
LATCC : London Air Traffic Control Centre
LATCO : Licensing of Air Traffic Control Officers (ICAO Study Group)
LAU : Local Approach Unit

LAWRS : Limited Aviation Weather Reporting Station

LB : Pounds (weight)
LB : Local Battery (circuits)

LC : Local Control
LCC : Lifetime Cycle Costing
LCD : Liquid Cristal Display
LCG : Load Classification Group
LCIPD : Local Convergence and Implementation Programme Document / Document CIP local
LCM : Late Change (modification) Message (designator) 
LCN : Load Classification Number
LCN : Local Communications Network

LCTD : Located
LDA : Landing Distance Available

LDA : Localizer Type Directional Aid

LDAH : Landing Distance Available Helicopter
LDB : Limited Data Block

LDG : Landing
LDGNSS : Local Differential Global Navigation Satellite System


LDI : Landing Direction Indicator
LDT : Logistic Delay Time
Lect : Lecture
LED : Light Emitting Diode
LEFCO : Project for the procurement of new ATM facilities in Nicosia ACC
LEFD : Local Essential Flight Details

LEN : Lenght
LEO : Low Earth Orbit
Lesson : Lesson / Demonstration
LF : Late Filer

LF : Later Filter
LF : Low Frequency

LFA : Local Flying Area
LFC : (Swedish) Air Defence Centre or (unit)
LFHB : Low Flying Handbook
LFL : Last (reported) Flight Level
LFP : Low Pass Filter
LFPP : Limited Flight Plan Processing

LFR Low-frequency Radio Range
LFS : Low-Fidelity-Simulation

LFU : Late Filer and Udater
LFV : Luftfartsverket (CAA of Sweden)

LGT : Light or Lighting

LGTD : Lighted

LH : Left Hand (turn)

LH : Lufthansa (airline)
LHCP : Left Hand Circular Polarisation
LHR : London Heathrow (UK)

LIDAR : Light Detection and Ranging
LIDO : Lufthansa Integrated Dispatch Operation

LIH : Light Intensity High

LIL : Light Intensity Low

LIM : Light Intensity Medium

LIM : Limit
LIM/MID/RAN : Limited Middle East Regional Air Navigation Conference (ICAO)
LIP : Light-pen

LIP : Limited Installation Program (e.g. TCAS)

LIRL : Low Intensity Runway Lights
LISREL : Linear Structural Relations
LIW : Label Input Window
LLC : Link Layer Control
LLC : Logical Link Control (RMCDE)
LLC-I : Logical Link Control - Class I
LLM : L-band Land Mobile
LLT : Low Light Television
LLTR : Low Level Transit Route
LLWAS : Low Level Windshear Alert System
LLZ : Localizer (part of an ILS system)

LM : Compass Locator at ILS Middle Marker
LM : Low/Medium ATC Complexity

LMM Compass locator at the middle marker
LMO : Leadership Management and Organisation 
LMT : Local Mean Time
LNA : Low Noise Amplifier
LNA/DPLX : Low Noise Amplifier/Diplexer
L-NAV : Lateral Navigation (provides computer description of aircraft's planned lateral flight path that can be tracked by the autoflight system; lateral path can be shown on map display.)

LNG : Long (used to indicate the type of approach desired or required)
LNO : Olno (Belgium sector indication)
LO : Local Oscillator

LO : Locator Outer

LO : Low
LoA : Line of Action
LOA : List of Abbreviations
LoA, LOA : Letter of Agreement ; Letter of Offer and Acceptance
LOC : Lines of Communications
LOC : Localiser Beam

LOC : Local or Locally or Location or Located

LOE : Line Oriented Evaluation
LOFT : Line-Orientated Flight Training
LoL : Loss of Licence

LOM : Compass Locator at the Outer Marker
LON : Longitude

LONG : Longitude
LOP : Local Operating Procedure
LOPAR : Low Powered Acquisition Radar
LORAN : Long Range Navigation (electronic pulse system for oceanic navigation)

LORAN-C : A hyperbolic grid navigation system
LOS : Level Safety
LOS : Line of Sight

LOS : Line-Oriented Simulation

LO : LOT Polish Airlines (airline)

LOW : Lower airspace
LR : Linear Regression
LRC : Legal ReCording
LRC : Legal Requirement Cell

LRC Long Range Cruise

LRG : Long Range
LRL : Local Recording Logistics
LRM : Line Replaceable Module
LRM : Logical Rejection Message

LRN : Long Range Navigation
LRR : Long Range Radar (SRE)
LRS : Local Route Sequence
LRU : Line Replaceable Unit
LRU : Lowest Replacable Unit
LRW : Long Range Warning 
LS : Loudspeaker
LSA : Logistic Support Analysis

LSAS : Longitudinal Stability Augmentation System (MD-11)
LSB : Least Significant Bit
LSC : Life Support Cost (Cyprus)

LSI : Large Scale Integration
LSP : Loud Speaker

LSR : Loose Snow on Runway(s)

LSRRTI : Leningrad Scientific Research Radio Technical Institute

LSS : Lightning Sensor System

LT : Left Turn

LT : Local Time
LT : Lithuania (ISO Country Code)
Lt : Sequence Time Requirement

LTD : Limited
LTF : Licensing Task Force
LTIOV : Latest Time Information of Value
LTM : Local Traffic Management
LTM : Long Term Memory
LTOG : Long Term Objectives Groups (EASIE, PHARE, FEATS, COPS etc)
LTP : Landing Threshold Point
LTP : Legal and Technical Panel
LTSS : Long Term Systems Studies

LTT : Landine TeleTypewriter
LTV : Load Threshold Values

LU : Late Updater
LU : Luxembourg (ISO Country Code)
LUG : Leerdam Users' Group
LUGS : Link up Glons-Semmerzake
LUX : Luxembourg (ISO countries Code)
LV : Laser Vision
LV : Latvia (ISO Country Code)

LV : Light and Variable (related to wind)
LVA : Large Vertical Aperture
LVB : Luchtverkeersbeveiliging (RLD-NL)

LVE : Leave or Leaving

LVL : Level

LVL CHG Level Change
LWG : Licensing Work Group

LX : Crossair (airline)

LY : El Al Israel Airlines (airline)

LYR : Layer or Layered

LZ : Balkan Bulgarian Airlines




M:M : Many-to-Many relationship

M : Mach Number  (followed by figures)

M : Manual Tuned NAVAID

M : Million
M : Modules (replaceable)
M : Symbol for Mega (10+6)
m : Symbol for milli (10-3)
m. : meter

m : Nautical mile (preceded by figures)
m/sec : Metres per second

M/ASI : Mach/Airspeed Indicator
M/T : Medium-Term

MA : Malev Hungarian (airline)
MA : Member Association
MA : Message Assurance
MA : Morocco (ISO Countries Codes)

MAA : Maximum Authorized IFR Altitude
MAC : Management Advisory Committee

MAC : Mean Aerodynamic Chord
MAC : Medium Access Control (RMCDE)
MAC : Message for the Abrogation of Coordination
MAC : Mid-Air Collision
MAC : Military Airlift Command
MACC : Manchester Area Control Centre
MACC : Military Area Control Centre
MACE : Multi-criteria analysis for Concept Evaluation
MACEN : Mando Centra
MACS : Multiple Access Communications System
MAD : Model of Activity for Design
MADAP : Maastricht Automated Data Processing and Display System
MADREC : Maastricht Data Recording
M-ADS : Modified Automatic Dependent Surveillance (ICAO)
MAESCAPE : Eurocontrol Simulation Capability and Platform for Experimentation tailored to Maastricht UAC requirements
MAESTRO : Means to Aid Expedition and Sequencing of Traffic with Research and Optimisation 

MAG : Magnetic
MAHF : missed Approach Holding Fix
MAHWP : Missed Approach Holding Waypoint

MAINT : Maintenance

MALS : Medium Intensity Approach Light System

MALSF : Medium Intensity Approach Light System with Sequenced Flashers

MALSR : Medium Intensity Approach Light System with Runway Alignment Indicator Lights
MAN : Manual Message
MAN : Metropolitan Area Network
MANACT : Manual Activation message
MANTEA : Management of Surface Traffic in European Airports

MAP : Aeronautical Maps and Charts
MAP : Mapping
MAP : Military Assistance Program

MAP : Missed Approach

MAPPER : Maintaining, Preparing & Producing Executive Reports
MAPt : Missed Approach Point

MAR : At Sea
MAR : Mode A Reconstructor

MARAS : Middle Airspace Radar Advisory Service
MARRES : Manual Radar Return Exploitation System
MARS : Maastricht Reserve System
MARS : Military Air Route Structure
MARSA : Military Authority Assumes Responsibility for Separation of Aircraft
MART : Message Acknowledge Response Time
MARTOS : MADAP Real-Time Operating System
MAS (UAC) : Maastricht Upper Area Control Centre
MAS : Manage Airspace
MAS : Manual Assume of Control Message

MAS : Manual A1 Simplex

MAS : Message Assurance Service
MAS : Middle Airspace
MAS : Military Agency for Standardisation
MAS : Multiple Access Store
MASAW : Minimum Safe Altitude Warning

MASI : Mach Airspeed Indicator
MASOR : Military Area Services Operations Room
MASP : Minimum Aviation Specification Performance
MASPS : Minimum Aircraft System Performance Specification (ICAO) ; Minimum Aviation System Performance Standards
MASS : Multi-Aircraft Simplified Simulator
MAST 4 : 4 States Integration and Maastricht Development Steering Group
MAST : Multi-Aircraft Simulation Terminal
MAT : Mackinnon Aerospace and Training
MAT : Message Acknowledge Time
MATCC : Military ATC Centre
MATE : Multi-Aircraft Training Environment
MATIAS : Magyar (Hungarian) Automated and Integrated Air Traffic Control System
MATO : Military Air Traffic Operations
MATRAC : Military Air Traffic Radar Control Centre
MATS : Manual of Air Traffic Services
MATSE : ECAC Transport Ministers' Meeting on the Air Traffic System in Europe
MATWP : Missed Approach Turning Waypoint

MATZ : Militairy Aerodrome Traffic Zone

MAU : Modular Avionics Unit
MAV : Medium Access Control
MAWP : Missed Approach Waypoint

MAX : Maximum

MAX CLB Maximum engine thrust for two-engine climb

MAX CRZ Maximum engine thrust for two-engine cruise
MAZ : Mini ASCAP-ZKSD Coupling
MB : Mega Byte
Mb : Millibars
MB : MariBor
MB-II : Multibus II (RMCDE)

MBA : Micro Burst Alert (used to warn of a loss of 30 knots or more associated with convective activity)
MBO : Management by Objectives
Mbps : Mega Bits per second
MBR : Mittel-Bereich radar

MBST : Microburst
MC : Main Computer
MC : Monaco (ISO Countries Code)

MCA : Minimum Crossing Altitude  
MCC : Main Computer Complex (Maastricht)
MCC : Military Control Centre
MCC : Mission Control Centre
MCDU : Maintenance and Control Display Unit
MCDU : Multi-Function Control and Display Unit (part of FMS)
MCDU : Multi-purpose Control and Display Unit (ACARS)
MCE : Management Centre Europe (seminars/courses)
MCF : Manning Calculation Formula
MCG : Maastricht Co-ordination Group
MCG : Minimum Climb Gradient
MCH : Modified Cooper-Harper rating scale for system workload assessment
MCMG : Military Committee Meteorological Group
MCP : Management Control Point

MCP : Mode Control Panel (pilots' interface to the autoflight system; usually located centrally just below cockpit glare shield)  
MCS : Master Control Station
MCS : Monitoring and Control System
MCS : Multi-Aircraft Cockpit Simulator
MCSG : Military Committee Staff Group
MCT : Maastricht Co-ordination Team

MCW : Modulated Continuous Wave

MCT : Maximum Continuous Thrust
MCTR : Military CTR
MCU : Main CWP-Unit

MCU : Modular Concept Unit (Spitzer)

MCU : Minimum Configuration Unit

MCU : Modular Component Unit
MD : Moldova (ISO Country Code)

MD : McDonnell-Douglas

MDA : McDonnell-Douglas Aerospace
MDA/H : Minimum Descent Altitude/Height

MDAU : Maintenance Data Acquisition Unit

MDCN : Military Diplomatic Clearance Number; for military aircraft
MDD : Meteorological Data Distribution (function)
MDF : Main Distribution Frame

MDF : Medium Frequency direction-finding Station

MDH : Minimum descent Height
MDI : Manage Document Inputs
MDI : Minimum Departure Interval

MDL Multipurpose Data Link
MDP : Maastricht Development Plan
MDP : MADAP Data Processor
MDS : Management Document Storage
MDS : Minimum Detectable Signal
MDT : Mean Down Time
MEA : Minimum En-route Altitude (ICAO)
MEB : Main Earthing Bar
MECA : Model for the Economical evaluation of the Capacities of the ATM system
MECO : Main Engine Cutoff
MECU : Millons of ECU

MEHT : Minimum eye height over threshold (for visual approach slope indicator system)

MED : Medium
MEDLL : Multipath Delay Lock Loop
MEF : Minimum Essential Facilities
MEFISTO : Modelling, Evaluating and Formalising Interactive Systems using Tasks and Interaction Objectives
MEG : Magnetoencephalography
MEL : Minimum En-route Level

MEL : Minimum Equipment List
MEMPAC : CBT on Memory, Perception, Cognition and Attention
MEO : Medium Earth Orbit
MES : Mobile Earth Station
MET : Meteorological or request METAR
MET : Meteorological (office)
MET/AIS : Meteorological and Aeronautical Information processing System
METAR : Aviation Routine Weather Report
METAR : Meteorological Aerodrome Report
METAR : Meteorological Aviation Routine Weather Report / Actual Report
MEURO : Millions of EURO
MF : Manning Factor
MF : Medium Frequency
MF : Metering Fix
MF : Multiplication Factor
MFA : Message Format Area
MFAL : Major Functional Areas List 
MFC : Multi-Frequency Coding (telephone system)
MFC/LB : Multi-Frequency Coding / Local Battery

MFD : Multi Function Display
MFDA : Military Flight Data Assistant
MFL : Military Flight List
MFLOPS : Million Floating Point Operations per Second
MFPU : Mobile Field Processing Unit
MFS : Message from Shanwick
MFUR : Most Frequently Used route
MGC : Main Graphics Controller
MGT : Management
MGV : Miss Generation Volume

MH : Malaysia Airlines (airline)

MHDF : Medium and high frequency direction-finding station (at the same location)

MHRS :Magnetic Heading Reference System
MHS : Message Handling Service
MHT : Multi Head Tracking
MHT : Multi Hypothesis Technique

MHVDF : Medium, high and very high frequency direction-finding station (at the same location)
Mhz : Megahertz

MI : Shallow (meteo)
MIB : Management Information Base
MIC : Microphone (VCS)
MICAM : Military Code Allocation Method

MID : Mid-point (related to RVR)
MID : Middle-East Region (ICAO) / Moyen-Orient
MIDAS : Man-machine Integration Design analysis System

MIDAS Multi-discipline Data Analysis System
MIDS : Multi-Function Information Distribution System
MIF : MTI Improvement Factor

MIFG : Shallow fog
MIG : Mikojan - Gurevich
MIL : Military
MILATCC : Military Air Traffic Control Centre
MILE : Multiple Integrated Laser Engagement System
MIL-HDBK : Military Handbook
MILREP : Military Representation
MILSATCOM : Military Satellite Communications

MILSPEC Military Specifications
MIL-STD : Military Standard
MIN : Message Identification Number
min : minutes

MIN : Minimum

MINIT : Minutes in Trail. A specified interval between aircraft expressed in time
MINIPLN : Set of Flight plan related information provided by an FPPS to an ARTAS Unit, used for track labelling

MINLINEUP : Minimum time to line-up for take-off
MIO : Military Sector Input Operator
MIP : Multinational Information Production
MIPS : Million Instructions per Second
MIR : Master Inspection Record
MIRACULIX : Multi Interface Radarformat Calculator and User Line Information Exchange

MIRL : Medium Intensity Runway Lights
MIS : Management Information Service/Systems User
MIS : Management Information System
MIS : Manual Input Station

MIT : Miles in Trail. A specified interval between aircraft expressed in nautical miles.
MITRE : Massachusetts Institute for Technology, Research and Engineering
MIW : Message In Window
MK : Macedonia (ISO Country Code)

MKR : Marker Radio Beacon
MLD : Military Liaison Division
MLDT : Mean Logistic Down Time

MLA : ManeuverLimited Altitude

MLE : Landing Gear Extended Placard Mach Number
MLS : Microwave Landing System
MM : Mental Model
MM : Middle Marker
mm : Millimetre

MMEL : Master Minimum Equipment List
MMI : Man-Machine Interface. See HMI
MMIL : Martin-Marietta International Link

MMO : Main Meteorological Office

MMO : Mach Max Operating
MMOC : Martin-Marietta Overseas Corporation
MMPI : Minnesota Multi-phasic Personality Inventory
MMR : Multi-Mode Receiver

MN Magnetic North
MNC : Major NATO Commander

MNCC : Multinational Coordination Centre

MNM : Minimum
MNPS : Minimum Navigation Performance Specification
MNPSA : Minimum Navigation Performance Specification Airspace
MNS : Mobile Network Services
MNT : Mach Number Technique

MNT : Monitor, Monitoring, or Monitored

MNTN : Maintain
MNWG : Multi-national Working Group
MOA : Memorandum of Agreement

MOA : Militairy Operating Area
MOB : Mobile
MOC : Memorandum of Co-operation
MOC : Minimum Obstacle/Obstrucion Clearance (required)

MOCA Minimum Obstruction Clearance Altitude
MOCBITE : Maastricht Operational Computer Based Information, Training and Examination System
MOD : Ministry of Defence

MOD : Moderate (used to indicate the intensity of weather phenomena, interference or static reports e.g. MOD RA = moderate rain)

MOD : Modified/Modification

Mode S Type of secondary surveillance radar (SSR) equipment which provides Mode A and Mode C interrogations, discrete address (Mode S) interrogations from the ground or air, and a data link capability

MODIS Moderate-resolution Imaging Spectrometer
MoF : Minister of Finance
MOF : Mode of Flight

MOGAS : Motor Gasoline

MON : Above Mountains
MON : Centre of Expertise Monitoring
MONA : Monitoring Aids
MONA User : Monitoring Aids User
MOPS : Minimum Operational Performance Standards (Specifications) / FAA
MOR : Military Operational Requirements
MORS : Mandatory Occurrence Reporting Scheme

MOS : Minimum Operating Standard
MOS : Minimum Operating Strip
MOSD : Mission, Objectives and Strategy Document
MOT : Ministry of Transport
MOT&E : Multinational Operational Testing and Evaluation
MOTNE : Meteorological Operational Telecommunications Network Europe
MOU, MoU : Memorandum of Understanding
MOUSES, MOUSES TF : Mode S Operational Use of Enhanced Surveillance Task Force

MOV : Move or Moving or Movement
MOW : Message Out Window
MOX (-B) : Maastricht Operational Telephone Exchange (version B)
MP : Manpower Planning

MP : Martinair (airline)
MP : Mental Picture
Mp : Microprocessor

MPa : Maximum Tyre Pressure Allowable
MPA : Maritime Patrol aircraft
MPA : Military Planning Assistant
MPC : Message Processing Centre
MPC : Military Planning Controller
MPDR : Medium Powered Doppler Radar
MPEG : Moving Pictures Expert Group

MPH : Statute Miles per Hour
MPL : Mini Flight Plan
MPO : Maastricht Project Office
MPO : Management Project Office
MPR : Medium Powered Radar
MPR : Swedish National Board for Measurement and Testing
MPRT : Menu Preview Response Time

MPS : Meters per Second

MPW : Maximum Possible Weight
MPS / MPSG : Manpower Planning Sub-Group
MPs : Manpower Planners
MPS : Minimum Performance Specification
MP-SEC : Management Planning System Evaluation and Control
MPT : Minimum Performance Transponder
MPX : Multiplex (Transmission)
MRA : Military Reserved Airspace

MRA : Minimum Reception Altitude
MRC : Military Radar Controller
MRC : Monitoring and Remote Control
MRCA : Multirole Combat Aircraft
MRDP : Multi Radar Data Processing
MRDPS : Multi Radar Data Processing System
MRDV : Multi Radar Daten Verarbeitung / Multi-Radar Processing System

MRG : Medium Range
MRI : Master Record Index (MAS - ODS)
MRK : Marker (RLB)
MRL : Minimum Risk Level
MRM : Minimum Required Manoeuvre (OCD)

MRP : ATIS/MET Reporting Point
MRRP : Minimum Risk Routing Point
MRS : Monitoring and Ranging Stations
MRSA : Mandatory Radar Service Area
MRT : Mean Response Time
MRT : Monitoring R/T, an ACM service message
MRT : Multi Radar Tracking
MRTS : Multi Radar Tracker and Server (System)
MRT-VU : Multi Radar Tracking using Variable Update
MRU : Projekt Marknadsföring Rekrytering Urval och Utbildning (SE) / Project for marketing, recruitment, selection and training for ATCO students, in Sweden
MRVA : Minimum Radar Vectoring Altitude
ms : millisecond

MS : Egypt Air (airline)

MS : Minus
MSA : Minimum Safe/Sector Altitude
MSAS : MTSAT Satellite Based Augmentation System 
MSAW : Minimum Safe Altitude Warning

MSB : CFMU – Management Support Bureau
MSB : Most Significant Bit
MSC : Maastricht Steering Committee
MSC : Meteorological Services Communication
MSC : Miscellaneous Simulation Facility
MS-DTS : Medium Speed-Data Transmission System
MSF : Master Simulation Facility
MSG : Manpower Sub-Group
MSG : Message
MSGDLP : Mode S Ground Data Link Processor

MSGSUM : Message Summary

MSGTXT : Message Text
MSK : Minimum Shift Keying
MSL : Mean Sea Level
MSP : Mode S Specific Protocol
MSP : Multi-sector planning
MSRT : Mean Services Restoration Time
MSS : Message Storage System
MSSA : Message Switching System
MSSR : Monopulse Secondary Surveillance Radar
MST : Multiple Sensor Tracking
MSTU : Multiple Stagger Trigger Unit
MSU : Management Storage Unit

MSU : Mode Select Unit
MSUP : Military SUPervisor
MT : Malta (ISO Country Code)

MT : Mountain
MTA : Military Training Area
MTAC : Multiple Time Around Clutter
MTAT : Multiple Time Around Targets
MTBCF : Mean Time Between Critical Failures
MTBF : Mean Time Between Failures
MTBR : Mean Time Between Removals

MTBUR : Mean Time Between Unscheduled Removal
MTCA : Medium Term Conflict Alert / Assistance (ODID)
MTCD : Medium Term Conflict Detection
MTCDR : Medium-Term Conflict Detection and Resolution
MTCEP : (Short) & Medium Term Capacity Enhancement Plan
MTD : Mean Down Time
MTD : Micro Tabular Display
MTD : Moving Target Detection
MTF : Modulation Transfer Function
MTI : Moving Target Indicator
MTMA : Major TMA
MTN : Mega Transport Network
MTOM : Maximum Take-Off Mass
MTOW : Maximum Take-Off Weight
MTP : Medium Term Plan
MTPA : Mobile Transponder Performance Analyser
Mtraq : Multi track quality 
MTS : Manoeuvrable Target Simulator
MTS : Memory Time Switch (ACS)
MTSAT : Multi-Functional Transport Satellite
MTTF : Mean Time To Failure
MTTR : Mean Time To Repair (CBN - CNG)
MTTRlru : Mean Time to repair LRU
MTTRp : Mean Time to repair product
MTTRsru : Mean Time to repair SRU
MTU : Master Trigger Unit

MTU : Metric Units

MTW : Mountain Waves

MTWA : Maximum take-off Weight Authorized
MU : Management Unit (ACARS)

MU : Mu Meters
MUAC : Military Upper Area Control (Centre)

MUD : Mud
MUDPIE : Multiple User Data Processing Interactive Environment

MUNI : Municipal
MURATREC : Multi Radar Track Reconstruction (System)
MUSAC : Multiple Switching and Confirming (VCS)
MUT : Mean Up Time
MUX : Multiplex

MVDF : Medium and very high frequency direction-finding station (at the same location)

MVE : Move

MW : Megawatt
MW : Microwave link
mW : Milliwatt
MWA : Message Warning Area
MWO : Meteorological Watch Office
MWP : Meteorological Working Position

MWP Meteorological Weather Processor
MWT(A) : Mean Waiting Time, Administrative
MWW : Upper Wind and Temperature Forecast (message)

MX : Mixed type of ice formation (white and clear)
MXCOP : MADAP Exit Co-ordination Point
MXFL : MADAP Exit Flight Level




N : Neper

N : North

N : No distinct tendency (in RVR during previous 10 minutes)
n : Symbol for nano- (10-9)

N1 : Engine low pressure rotor speed

N90 : New York Tracon
N/A : Not Applicable
N/C : Not Comparable

NA : National Administration

NA : Not Available

NA : Not Authorized
NABS : National Augmentation Broadcast System
NAC : North Atlantic Council

NACA National Advisory Committee for Aeronautics
NACMA : NATO Agency for Air Command and Control System Management
NADC : NATO Air Defence Committee
NADGE : NATO Air Defence Ground Environment
NADIN : National Airspace Data Interchange Network

NADIN II National Airspace Data Interchange Network II (the national digital message switching network for aeronautical data)
NAEW & C : NATO Airborne Early Warnings (and Control)
NAFTA : North American Free Trade Agreement (Canada, US, Mexico)
NAGU : Notice Advisory to GLONASS Users
NAI : Non Automated Initiation
NAIA : New Athens International Airport
NAIS : Norwegian Aeronautical Information System
NAK : Negative Acknowledgement (ICAO)
NALLA : National Long Lines Agency
NAM : North America Region (ICAO)
NAMC : National Airspace Management Cell
NAME : Nadge - ADMAR Message Exchange
NAMILCOM : NATO Military Committee
NAMSA : NATO Maintenance and Supply Agency
NAMSO : NATO Maintenance and Supply Organisation
NANU : Notice Advisory to NAVSTAR Users
NAP : National Associated Programmes
NAR : North American Route System
NARDS : Norwegian Automatic Dependent Surveillance
NARFA : National Radio Frequencies Agency
NARG : Navigation Aids and Area Navigation Group (ICAO - EANPG)
NARSIM : NLR ATC Research Simulator
NAS : National Airspace System 
NAS : Naval Air Station

NAS National Aircraft Standard
NAS : Network Administration System (DAKOS, FFM / RAPNET - MAS UAC)

NASA : National Aeronautics and Space Administration (US)
NASA RTLX : NASA Raw Task Load indeX
NASA TLX : NASA Task Load indeX
NASC : National AIS System Centre
NASPAC : National Airspace Performance Analysis Capability
NAS-Plan : National Airspace Plan
NAT  : North Atlantic Tracks
NAT ADS : North Atlantic Automatic Dependent Surveillance
NAT ATMG : North Atlantic Air Traffic Management

NATCA National Air Traffic Controllers Association
NAT CADAG : North Atlantic Communications Automation and Data Link Applications Group
NAT CMA : North Atlantic Region Central Monitoring Agency
NAT IMG : North Atlantic Implementation Management Group
NAT MWG : North Atlantic Mathematicians Working Group
NAT OPS MNG : North Atlantic Operations Managers Meeting
NAT RSSIG : North Atlantic Reduced Separation Standard Implementation Group
NAT SPG : North Atlantic Systems Planning Group (ICAO)
NAT VSIG : North Atlantic Vertical Separation and Implementation Group
NAT NAM : North Atlantic / North America (ICAO Regions)
NATCON : North Atlantic Concept
NATINAD(S) : NATO Europe Integrated Air Defence (System)
NATMC : NATO Air Traffic Management Committee (former CEAC)
NATN : (Swedish) National Aeronautical telecommunications Network
NATO : North Atlantic Treaty Organisation
NATS : National Air Traffic Services (UK)
NATSPG : North Atlantic Systems Planning Group (ICAO)
NAT-TFG : North Atlantic Air Traffic Forecasting Group 
NAV : Navigation
NAV-1 : Radar Data System (Portugal)
NAVAID : Navigation(al) Aid
NAVDB : Navigation Data Base
NAVSAT : Navigation Satellite
NAVSEP : Navigation and Separation Specialist Panel
NAVSTAR : Navigation Satellite Timing and Ranging System

NB : Northbound

NBAA National Business Aircraft Association

NBFR : Not Before

NBO : (in a NOTAM)  N: Indicates for immediate attention of aircraft operators, B: for inclusion in PIB's and O: Operationally significant for IFR flights.

NC : No Change
NC : Non-Critical
NC : Normally Connected
NCAA : NATO Civil Aviation Authority
NCAA : Norwegian Civil Aviation Authority
NCAB : National Civil Aviation Board
NCAIC : National Civil Aviation Information Centre
NCCA : No Clearance to Civil Aircraft

NCD : No Computed Data
NCIPD : National CIP Documents
NCMS : Network Channel Management Station
NCN : Non Compliance Notification
NCOP : Entry Coordination Point
NCS : Navigational Computer System
NCS : Network Communication System
NCS : Network Control System / Station (CBN - CNG)
NCW : Non Conformance Warning
ND : Navigation Display
ND : Network Digit (CCITT X.121 Structure)
NDA : National Distribution Agency
NDA : Next Data Authority (ICAO)

NDB : Nav Data Base
NDB : Non-Directional Beacon
NDE : Node Processor
NDS : Non-Deviation Status
NDS : Nuclear Detection System
NE : North-East
NEAN : North European ADS-B Network
NEAP : North European Application Project

NEB : Northeast Bound
NECP : Entry Coordination Point

NEG : No or Negative or permission not granted or that is not correct
NEGATIVE RA : RA applying maximum vertical rate (eg don't descend > 500 ft/min)
NEI : Noise Exposure Index
NERC System : New En-Route Centre System (UK)
NERC : New En-Route Control Centre (UK)
NES : Navigation Ground Earth Stations

NESDIS National Environmental Satellite, Data, and Information Service
NET : Network Entity Title
NETCAP : Network Capacity (simulator)
NET-TF : Circuit Provisioning and Network Management Task Force

NEWCTOT : New Calculated Take-Off Time

NEWEOBD : New Estimated Off-Block Date

NEWEOBT : New Estimated Off-Block Time

NEWETOT : New Estimanted Take-Off Time

NEWPTOT : New Provisional Take-Off Time

NEWRTE : New Roure
NEXRAD : Next Generation Weather Radar
NF : Noise Figure

NFDC : Natianal Flight Data Center (USA)
NFL : Entry Flight Level (Re-Entrant Flight)
NFPPDS : National Flight Plan Processing System
N-FRG : Northern Federal Republic of Germany
NFS : Network Filing System

NGATM New Generation Air Traffic Manager

NGT : Night
NHIP : Nordic Harmonisation and Integration Programme
NIK : Nicky VOR

NIL : None or I have nothing to send to you
NIM : Navigational Integrity Monitoring (ICAO)
NIMA : National Imagery and Mapping Agency (of the US Department of Defence (DOD)
NIT : Nordic Implementation Team

NJRASA : Northern Joint Radar Advisory Service (UK)
NL : the Netherlands (ISO Country Code)
NL : Network Layer
NLA : New Large Aircraft
NLC : Netherlands Aviation College(NL) / Nederlands Luchtvaart College
NLES : Navigation Land Earth Station
NLM : Nederlandse Luchtvaart Maatschappij (airline)

NLM Network Loadable Module
NLR : Nederlands Lucht- en Ruimtevaart Laboratorium (NL) / National Aerospace Laboratory 
NLT : Not Later Than
NM : Negotiation Manager (PATs)
NM : North Marker
nm, NM : Nautical Mile (1.852 m)
NMAC : Near Mid-Air Collision

NMC National Meteorological Center
NMC : Network Management Centre (Cell) (RAPNET / MAS UAC / DAKOS)
NME/ad hoc : Ad Hoc Working Group of National Management Experts
NMIL : Nieuw Milligen

NML : Normal

NMR : Nautical Miles Radius
NMR : National Military Representative

NMS : Navigation Management System
NMS : Network Management System / Switch

NMU : Navigation Management Unit

NNE : North-North-Eeast

NNW : North-North-West
NO : Norway (ISO Country Code)

NOAA : National Oceanic and Atmospheric Administration
NOAA : New Optimised Approach for ATSM Workshop 
NOC : Network Operation Centre
NODE : NATS' Operational Display Equipment
NOF : NOTAM Office
NOG OA&M : NOG Operations, Administration & Maintenance Subgroup (CNG - CBN)
NOG : Northern Telecom Network Operator's Group (CNG - CBN)
NOG-FSG : NOG Features Subgroup (CNG - CBN)
NOMAS : NOTAM Management System (NL)

NONSTD : Nonstandard

NOPT : No Procedure Turn Required
NORAC : No Radio Contact

NORDO : No Radio (Aircraft without radio)
NOS : Network Operating System

NOSIG : No Significant Change (Used in trend-type landing forecasts)
NOTAM : Notice to Airmen ( A notice containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations)

NOTAMN : New Notam

NOTAMR : Notam Replacing another Notam

NOTAMC : Notam Cancelling another Notam
NP : Network Protocol
NPA : Non Precision Approach
NPDU : Network Protocol Data Unit (RMCDE)
NPL : Night Plan
NPO KIP : [Russian]. Scientific Production Organisation ; Scientific Production Institute of Space Device Building
NPO PM : [Russian]. NPO Prikladnoi Mekhaniki (RU)Scientific Production Institute for Applied Mechanics
NPO : Scientific Production Organisation [Russian]
NPRM : Notice of Proposed Rule Making (FAA)
NPV : Net Present Value
NPV : Non-Precision Approach procedure with Vertical Guidance
NR : Noise Rating
Nr. : Number
NRF : NATS Research Facility

NRH : No Reply Heard
NRL : (US) Naval Research Laboratory
NRP : North Reference Pulse

NRP : National Route Plan/Program
NRZ : Non Return to Zero (RMCDE)
NRZI : Non Return to Zero Inverted (RMCDE)
ns : Nanosecond
NS : Navigation Separation
NS : Next Sector

NS : Nimbostratus
NSAP : Network Service Access Point
NSC : New Scottish Center

NSC : No signifant clouds (meteo)
NSC : Notice to Airmen Selection Criteria
NSD : Navigational Status Display
NSDU : Network Service Data Unit
NSE : Navigation System Error
NSM : Network System (Sensor) Manager
NSSG : Navigation and Separation Sub-Group
NSSR : Next/New Secondary Surveillance Radar Code 
NSTB : National Satellite Test Bed
NSVN : NATO Secure Voice Network

NSW : No significant weather (meteo)
NSWC : Naval Surface Warfare Centre
NT : Northern Telecom (RMCDE)

NTAP : Notice to Airman Publication
NTE : Not to exceed
NTM F/T SIM : Nattenheim Fast Time Simulation
NTN : Network Terminal Number (CCITT X.121 Structure)
NTRY : Entry
NTSB : National Transportation Safety Board (US)
NUA : Network User Address
NUDET : Nuclear Detection

NVFR : VFR by night
NW : North-West

NW : Northwest Airlines (airline)

NWB : Northwest Bound

NWS : National Weather Service
NXRPT : Next Reporting Point
NXT : Next

Nl Engine Revolutions per Minute (percent)




O/R : On Request

O/T : Other Times

O : Oceanic

OA : Olympic Airways (airline)

OAC : Oceanic Area Control Centre
OACA : Office of Airports and Civil Aviation / Office des Aéroports et de l'Aviation Civile
OACC : Oceanic Area Control Centre
OAG : Official Airlines Guide

OAS : Obstacle Assessment Surface
OAS : Oceanic Automation System (ICAO - ADS)
OASIS : Oceanic Area System Improvement Study
OASIS : Open Architecture for Simulation Systems
OASIS : Open ATC System Integration Strategy (OCD)
OASIS : Operational Application of Special Intelligence Systems
OASYS : Obstacle Avoidance System
OAT : Operational Air Traffic

OAT : Outside AirTemperature

OATS Orbit and Attitude Tracking
OBA : Off-Bore Sight Angle
Obj. : Objective in CIP
OBR : Obnova Radiolomunikaci (YU) / Renewal of Air-Ground Communications
OBS : Organisational Breakdown Structure
OBS : Observe or Observation Status

OBSC : Obscured, Obscure, or Obscuring

OBST : Obstacle, Obstruction

OBSTL : Obstrucion Lights
OBT : Off Block Time

OBTEX Offboard Targeting Experiments
OC : Object Correlator
OCA : Oceanic Control Area
OCA : Obstacle Clearance Altitude

OCAP : Out of Control Action Plan

OCC : Operations Control Center

OCC : Occulting (light)
OCD : Operational Concept Document for the EATCHIP Phase III System Generation

OCH : Obstacle Clearance Height

OCL : Obstacle Clearance Limit
OCL : Oceanic CLearance delivery

OCNL : Occasional or Occasionally
OCM : Oceanic Clearance Message
OCP : Obstacle Clearance Panel
OCP : Operational Computer Programme
OCR TF : Operational and Certification Requirements Task Force
OCR : Operational and Certification Requirements
OCR : Optical Character Recognition

OCS : Obstacle Clearance Surface
OCS : Operational Control Segment
OCT : Onward Clearance Time
OCT : Operational Control Terminal (VCS)
OCTF : Operation Concept Task Force
OCU : Operational Conversion Unit
OCV : Operational Coverage Volume
OCX : New Object similar to VBX
OD : Organisation and Development (Unit attached to the Director General)
ODA : Open Document Architecture
ODAPS : Oceanic Display And Planning System

ODAPS Operational OGE Data Acquisition and Patch Subsystem

ODAX : Name of military exercises
ODC : Office of Defence Cooperation
ODETE : On-line Data Exchange Terminal
ODF : Oceanic Development Facility (ICAO)
ODIAC, ODIAC-TF : Operational Development of Initial Air/Ground Data Communications Task Force
ODID : Operational Display and Input Development
ODIF : Open Document Interchange Format
ODIN : (Swedish) Briefing System (AIS)
ODP : ATM Operational Requirements & Data Processing
ODS : Operational Display System (ESCO)
ODS : Operator input and Display System
ODT : Operational Requirements and Data Processing Team
ODU : Output Distribution Unit
OECD : Organisation for Economic Co-operation and Development (= OCDE)
OEM : Original Equipment Manufacturer
OFAC : Office Fédéral de l'Aviation Civile (CH) / Federal Office for Civil Aviation (=FOCA)
OFFPDR : Off Predetermined Route
OFIR : Oceanic FIR
OFIS : Operational Flight Information System
OFL : Off-Line
OFS : Ordered Field Sequencing

OFST Lateral Offset Active Light

OGE Operational Ground Equipment

OGM : Objectives > Goals > Mission
OH : Operational Handbook

OHD : Overhead
OHP : Over Head Projector
OHTF : Operational Harmonisation Task Force
OIDS : Operational Information Display System
OIS : Obstacle Identification Surface

OIS : OGE Input Simulator
OJT : On-the-Job Training
OJTI : On-the-Job-Training Instructor

OK : Czech Airlines (airline)
OL : Operating Location
OLDI : On-Line Data Interchange
OLDI : On-Line Data Interchange (automation in ATC)
OLDINA : OLNO, Diekirch, Nattenheim (Nattenheim area)
OLDISP : OLDI Specialist Panel
OLEVAT : On Line Exercise of Validation of Aircraft Trajectories
OLR : Off Load Route
OLS : Off Line System

OM : Operations Manual
OM : Outer Marker
OMC : Operational Monitoring Complex ; Operational Monitoring Cell (ACAS, AIG Sub-group)
OMD : Operational Management Domain
OMG : Operational Monitoring Group (ACAS)
OMI : Organisation Maritime Internationale / International Maritime Organisation (=IMO)

OMS : On-board Maintenance System
ONL : On-Line
ONP : Open Network Provision (Telecommunications)

OO : Skywest Airlines (airline)

OA : Object Oriented Analysis
OOD : Object Oriented Design
OOOI : Out (Departure Block Time)-Off (Take-off)-On (Landing)-In (Arrival Block time)
OOP : Object Oriented Programming
OOP : Operational Outline Programme
OOR : Outline Operational Requirement
OP : Operational (issues)
OP : Organisational Productivity

OPA : Opaque, white type if ice formation
OPADD : Operating Procedures for AIS Dynamic Data 
OPAL : Optimisation Platform for Airports, including Landside

OPC : The control indicated is operational control
OPD : Operational Procedures Document (EAD)
OPB : Outer Performance Boundary (Tunnel Concept)

OPIF : Operator Interface
OPLAN : Operational Plan
OPM : Office of Personnel Management
OPM : Operational Position Management
OPMET : Operational Meteorological Information

OPN : Open or Opening or Opened
OPN : Operational Planning Notes (MADAP-KARLDAP)

OPR : Operator or Operate or Operative
OPR : ATM Operational Requirements (EATCHIP Domain) ; ATM Working Rules and Operational Requirements
OPS : Operational Services, Centre of Expertise EEC
OPS : Operations

OPS : CFMU/FMD – Operations Section
OPSEC : Operational Security
OPSP : Operations Panel
OPSroom : Operations Room

OPT : Operational Testing

OPT Optimum

O-QAR Optical Quick Access Recorder

OQPSK : Offset Quadrature Phase Shift Keying
OR : Operational Requirement
ORA : Operational Research and Analysis Group
ORCAM : Originating Region Code Assignment Method

ORD : Indication of an Order

ORGMSG : Original Message

ORGN :Original

ORGRTE : Original Route

ORIG : Original
ORD : Operational Requirements Document 
ORM : Operational Reply Message 
ORMAQ : Operation Room Management Attitudes Questionnaire
ORQ : D-OTIS Request Message
ORs : Operational Requirements
ORSG : Operational Requirements Sub-Group

ORT : Owner Requirements Table
ORTF : Operational Requirements Task Force

OS : Australian Airlines (airline)
OSC : Operations Steering Committee
OSCAR : Orbiting Satellite Carrying Amateur Radio
OSD : Operational Scenarios Document
OSF : Open System (Software) Foundation
OSF : Open System Foundation
OSG : Operational Services Group (MAS)

OSI Open Sytem Interconnection (ISO defined communications architecture used in data link to permit heterogeneous data communication systems to be interconnected in order to allow the reliable exchange of messages without regard to the implementation of the networks and physical media through which the messages pass)
OSIE : OSI Environment

OSM : CFMU/ENGD - Operational Systems Management Section

OSR : CFMU/URB - Operational Systems Requirements Team
OST : Operational Support Traffic

OSV : Ocean Station Vessel
OTD : D-OTIS Delivery Message
OTD : Operational Target Date
OTD : Other Training Device
OTF (VHF-OTF) : Operational VHF Task Force
OTF : Operational Task Force
OTF : Operational, Technical and Financial Working Group
OTF/BFWG : Combined Operational, Technical/Budgetary & Financial Working Group

OTFP Operational Traffic Flow Planning
O-TGS : ODS - Target Generation System
OTH (R) : Over The Horizon (Radar)

OTLK : Outlook (used in SIGMET for volcanic ash and tropical cyclones)

OTP : On Top
OTP : Overall Test Plan
OTR : Operational Turn Around
OTS : Oceanic Track System
OTS : Off-The-Shelf
OTS : Organized Track System

OTS : Out of Servide
OTSG : Operational Training and Selection Group
OTT : D_OTIS Termination Message
OTV : Orbital Transfer Vehicle

OU : Croatia Airlines (airline)

OUR : CFMU Operational User Requirements (FORM)

OUTB : Outbound
OUMSESTF : Operational Use of Mode S Enhanced Surveillance Task Force
OUNS : Operational Navigation System
OURASIE : Ourasie Toolkit : software X-windows toolkit built above Xt Intrinsics layer (CENA in-house product)

OV : Estonian Air (airline)

OV : Overseas National Airways

OVC : Overcast (meteo)

OVR : Over
Own : TCAS II equipped aircraft - source of TCAS event




P… : Prohibited Area

P : Prefix (CCITT X.121 Structure)

P : Procedure-Required Tuned NAVAID
P&H : Press and Hold (mouse)
P,R,D Area : Prohibited, Restricted, or Danger Area
P.ACCs : Pairs of ACCs
p.t.t : Push-to-Talk
PA : Participating Area
PA : Precision Approach
PA : Provisional Acceptance
PAA : Plot Accuracy Analysis
PABX : Private Automatic Branch eXchange
PAC : Pacific Region (ICAO)
PAC : Preliminary Activation message 
PAD : Packet Assembler Disassembler

PAEW : Personnel and Equipment Working
PAK : Pilot Acknowledgement (service)
PALLAS : Phased Automation of the Hellenic ATC System (new Greek ATC System)

PALS : Precision Approach Lighting System (specify category)
PAM : Pilot Acknowledgement Message
PAM : Program for Analysis of MADAP
PAMCS : Panel on Air Space Management and Control Systems
PANS : Procedures for Air Navigation Services
PANS-OPS : Procedures for Air Navigation Services - Aircraft Operations
PANS-RAC : Procedures for Air Navigation Services - Rules of the Air and Air Traffic Services
PAPI : Precision Approach Path Indicator
PAQ : Position Analysis Questionnaire
PAR : Planning, Analysis and Reporting
PAR : Precision Approach Radar
PARADISE : Prototype of an Adaptable and Reconfigurable ATM Demonstration and Integration Simulator Environment
PARI method : Precursor, Action, Result, Interpretation Method  
PARI : Precursor, Action, Result, Interpretation

PARL : Parallel
PARZOC : Parabolic Approximation of Aircraft Performance for use in a ZOC

PAT : Pattern
PAT : Provisional Acceptance Testing (CNG - CBN)
PATA : Polish Air Traffic Agency
PATCG : PHARE Advanced Tools Co-ordination Group
PATCHWORK : Polish ATC Harmonisation Work programme (EAS)
PATCO : Professional Air Traffic Controllers Association 
PATN : PHARE experimental Aeronautical Telecommunication Network
PATROCLOS : Peripheral Airports Terminal Radars, ODS and Centrally Linked Operations System
PATs : PHARE Advanced Tools
PATWAS : Pilot Automatic Telephone Weather Answering Service
PAU : Primary Authorised User
PAX : Passengers

PAWES Performance Assessment and Workload Evaluation
PB : Project Board

PBD Place Bearing/Distance (way point)
PBE : Peripheral Bus Extender (CBN - CNG)
PBL : Problem-Based Learning
PBRA : Plot Based Resolution Analysis
PC : Personal Computer
PC : Planning Controller ; Provisional Council (Eurocontrol)
PCA : Physical Configuration Audit
PCB : Printed Circuit Board
PCC : Peripheral Computer Complex
PCC : Planning Co-ordination Controller
PCC : Polygone Co-ordination Centre
PCC : Project Co-ordinating Committee (PETAL)
PCCB : Program Change Control Board (FPPS/DECADE)
PCD : Personal and Career Development
PCD : Planning Controller Display
PCD : Probability of Code Detection

PCD : Proceed or Proceeding
PCFL : Preferred Cruise Flight Level
P-channel : Packet Mode Channel
PCI : Permanent Commission for Investigation (on ATS incidents) ; Permanent Committee of Inquiry
PCI : Protocol Control Information
PCIP : Pilot Conversion and Implementation Plan
PCL : Pending and Coast List

PCL : Pilot Controlled Lighting
PCL : Procedure Changeover Lines (IFF)
PCM : Planning Co-ordination Message
PCM : Pulse Code Modulation
PCMP : Project Configuration Management Plan (MAS - ODS)
PCMT : Plan Commun à Moyen Terme / Common Medium-Term Plan (=CMTP)
PCN : Pavement Classification Number
P-Code : Precise/Protected Code
PCP : Project Control Plan
PCPU : PCM Central Processing Unit (VCS)
PCR : Periodic Contract Request (ICAO)
PCR : Post Conference Report
PCR : Problem Change Request
PCS : Process Control System
PCT : Planning Control Theory
PCV : Probability of Code Validation
PCX : A window compatible BIT format
PD : PHARE Demonstration
PD : Plan Display
PD : Pointing Device

PD Profile Descent
Pd, Pdet : Probability of detection
PD/1 : PHARE Demonstration 1
PD/1+ : PHARE Demonstration 1+
PD/1++ : PHARE Demonstration 1++
PD/2 : PHARE Demonstration 2
PD/2+ : PHARE Demonstration 2+
PD/3 : PHARE Demonstration 3
PDA : Planning Co-ordination Message Display Area
PDA : Plot Detection Analysis

PDB Performance Data Base
PDC : Peripheral Device Controller
PDC : Pre-Departure Clearance (message)
PD-Channel : Packet Data Channel
PDES : Pulse Doppler Elevator Scan
PDF : Percentage of Delayed Flights (Delay Parameter Abbreviations)
PDG : Procedure Design Gradient
PDME : Precision Distance Measuring Equipment
PDN : Public Data Network
PDOP : Position Dilution of Precision
PDP : Polar Diagram Plotter
PDR : Pre-Determined Route
PDR : Preliminary Design Review
PDRP : Problem Detection and Resolution
PDS : Programme Development System
PDTWG : Plot Data Transmission Working Group
PDU : Power Distribution Unit
PDU : Protocol Data Unit (RMCDE)
PE 90 : Parameters of Earth, 1990. Russian Geodetic System
PE : Processor Element (CBN - CNG)
PE : Protected Earth

PE : Ice Pellets
PEA : Parameter and Environment Assembler
Pressure Error Correction

PEL : Planned Entry Level (to a sector or volume of airspace) (ODID)
PELA : Proficiency test in English Language for ATCOs
PEM : Phone Emergency Module
PENS : Pan-European Fixed Network Service
PEP : Performance Engineering Programme (long-term scientific studies
PER : Packet Encoding Rules

PER : Performance

PERM : Permanent

PERF : Performance
PERT : Programme Evaluation and Review Technique
PES : Proposed Eurocontrol Standard Document
PETAL : Preliminary Eurocontrol Tests of Air/Ground data Link
PEX : PHIGS Extended X-Windows System
PF : Pilot Flying
PFA, Pfa : Probability of False Alarm
pFAST : passive Final Approach Spacing Tool
PFD : Planned Flight Data (CFMU - CASA)
PFD : Primary Flight Display
PFD : Probability of Failure Detection
PFE : Path Following Error
PFI : Private Finance Initiative
PFL : Planned Flight Level
PFLext : Probability of Failure/Fault Localisation, external
PFLint : Probability of Fault Localisation, internal
PFM : Pre-Flight Messages (EW)
PFN : Pulse-Forming-Network
PFR : Probability of Failure Repair
PGMP : Pilot Group on ATCO Manpower Planning

PGS : CFMU/MSB - Personnel General Services Team
PHA : Preliminary Hazard Analysis
PHARE : Poland, Hungary Aid for Restructuring of the Economy (European Commission)
PHARE : Programme for Harmonised Air Traffic Management and Research in Eurocontrol ; Programmed for Harmonised Research in Europe
PHAROS : Plan Handling and Radar Operating System (NL - Military)

PHIBUF Performance Buffet Limit
PHIGS : Programmer's Hierarchical Interactive Graphics System

PHINOM : Nominal Bank Angle
PI : Performance Indicator
PI : Peripheral Interface (CBN - CNG)
PI : Procedure Turn to Intercept (ARINC 424 Path Terminator)
PIAC : Peak Instantaneous Aircraft Count
PIB : Policy Information Base
PIB : Pre-flight Information Bulletin (plain language)
PICASSO : Control, Analysis and Monitoring of the Spanish Air Navigation System. Statistical application
PID : Pilot Information Downlink (service)
PIM : Programme Implementation Management
PIP : Plug In Panel
PIP : Product Improvement Package/Programm
PIREP : Pilot Report (ICAO)

PIREPS Pilot Reports
PIRG : Planning and Implementation Regional Groups (ICAO, al)
PIU : Parent IFPS Unit

PJE : Parachute Jumping Exercise

PK : PIA Pakistan International (airline)

PL : Ice Pellets (meteo)
PL : Poland (ISO Country Code)
PL : Pseudolite

PLA : Practise Low Approach
PLANO : Procedures Linked to Abating Noisy Operations (ANCAT TF)
PLB : Personal Locator Beacon
PLC : Planning Controller (also known as Coordinator)
PLL : Phase Locked Loop
PLMN : Public Land Mobile Network

PLN : Flight Plan
PLN : Flight Plan Conformance (new name is FLIPCY)
PLP : Packet Layer Protocol

PLVL : Present Level

PLW : Plow, Plowed

PMAT : Portable Maintenance Acces Terminal
PMB : Programme Management Board
PMB : Project Management Bureau
PMB : Project Management Bureau
PMC : Project Management Cell
PMCG : Preliminary Maastricht Co-ordination Group
PMCS : Performance Management Computer System
PMCT : People Management Core Team
PMD : Pre-warning Message for Departure
PME : Pre-warning Message Entry

PM/FL : Process Monitoring / Fault Location
PMO : Pre-warning Message OAT

PMO : Prorgram Management Organization
PMP : Project Management Plan
PMR Steering Committee : Planning Monitoring and Reporting Steering Committee
PMS : Performance Management / Monitoring System
PMT : Plan à Moyen Terme (MTP)
PMW : Project Management Workbench  
PMX : Planning Message Exit

PN : Prior Notice Required

PND : Primary Navigation Display
PNF : Pilot Not Flying

PNR : Point of No Return

PNR : Prior Notice Required

PO : Dust devils (meteo)

PO : Polar Air Cargo (airline)
PoACCS : Portuguese Air Command and Control System
PoAF : Portuguese Air Force
POB : Persons On Board
POC : Point of Contact
POD : Port of Debarkation
POE : Port of Embarkation
POEMS : Pre-Operational European Mode S Station
POEMS : Pre-Operational (development) European Mode S Enhanced Surveillance
POG : Point of Gaze
POR : INMARSAT Pacific Ocean Region
POR : Pacific Ocean Region
PoR : Point of Risk
POS : Position
Positive RA : RA applying minimum vertical rate (eg climb)

POS INIT Position Initialization
POSIX : Portable Operating System Interface for Computer Environments

POS REF Position Reference

POSS : Possible
PPC : Physical Protected Circuit
PPC : Policy Planning Committee

PPC : CFMU/ENGD - Projects, Procurement & Communication Section
PPD : Aircrew Preferences Downlink (Service)
PPD : Pilot References Downlink
PPD : Plans and Policy Division
PPI : Plan Position Indicator
ppi : Points Per Inch or points per inch
PPL : Private Pilot License
PPM : Pages per Minute
PPM : Pulse Position Modulation

PPO : Prior Permission Only

PPOS Present Position

PPR : Prior Permission Required
PPS : Precision Positioning Service/System
PPS, pps : Pulses Per Second

PPSN : Present Position
PPSN : Public Packet Switching Network
PQM : Project Quality Manager
PQP : Project Quality Plan

PR : Banks (meteo)
PR : Position Reporting
PR : Primary Radar
PR : Pseudorange
PR, PRI : Primary (radar or unit)
PR/PSR : Primary (Surveillance) Radar
PRA : Plot Resolution Analysis
PRA : Primary Rate Access
PRAISE : Preparation for Research and Development in Support of EATMS programme
PRAISE : Preparation of Functional Concepts from EATMS Operational Requirements
PRC : EEC business area - support to performance review
PRC : Performance Review Commission (New Convention)
PRE : Preview
PRE : Previous Centre

PREDICT : CFMU – Pre-Tactical System
preC : PreCouncil (= to replace CE)

PRF : Pulse Repetition Frequency – pertaining to radar

PRFG : Aerodrome Partially covered by Fog
Pre-OJT : Pre-On-the-Job Training

PREV : Previous
PREVI : Data Processing system to support the forecast and regulation of the air traffic (F)
PRF : Percentage of Regulated Flights(Delay Parameter Abbreviations)
PRF : Pulse Repetition Frequency (or recurrence)
PRI : Primary
PRI : Pulse Repetition Interval
PRIF : PROC Interface Tool

PRKG : Parking
PRL : Pilot Request, Level (service)

PRM : Precision Runway Monitor
PRN Code : Pseudo Random Noise Code
PRN : Pseudo Random Noise
P-RNAV : Precision Area Navigation
P-RNAV : Precision RNAV
ProATN : Prototype Aeronautical Telecommunications Network

PROB : Probability

PROC : Procedure
PROC : Procurement (tool)
PRODAT : PROSAT Data Link Experiment

PROF : Profile
PROFI : Multinational Project Financing

PROG : Progress Page on MCDU
PROM : Programmable Read Only Memory

PROP : Propellor
PRORES : Problem Resolution
PROSAT : Program Satellite (European Space Agency)
PROSIT : Problem Situation

PROV : Provisional
PROVE : European ATC Pre-operational Validation and Experimental Trials Platform
PRP : Pulse repetition Period
PRQ : Pilot Request (service)
PRR : Performance Review Report
PRR : Pilot Request, Route (service)
PRS : Performance Review System
PRS : Picture Repetition Store
PRSG : Performance Review Sub-Group
PRT : Preferences Tool
PRT : Processing Response Time 
PRU : Performance Review Unit (New Convention)

Ps : Pressure, static - air data mearsurement

PS : Pacific Southwest Airways

PS : Plus
PS : Position Symbol
PS : Power Supply (ACS)
PS : Problem Solver (PATs)
PSA : Passive Slot Allocation
PSA : Primary Subject Area
PSA : Provisional Site Acceptance
PSAP : Presentation Service Access Point

PSAL : Provisional Slot Allocation List
PSB : Parallel System Bus 
PSC : Performance, Standard, Conditions
PSC : Project Steering Committee
PSDN : Packet Switched Data Network
PSDN : Public Switched Data Network
PSE : Primary Surveillance Equipment

PSG : Passing
PSG : Programme Steering Group

Psi : Pounds/square inch
PSMC-Channel : Packet System Management and Control Channel
PSMSL : Permanent Service for Mean Sea Level

PSN : Position
PSN : Public Switch Network (DFS = sub-network RAPNET, CBN = system of the national ATS)

PSP : Pierced Steel Planks
PSP : Primary Spare Part
PSPDN : Packet Switched Public Data Network

PSR : Packed Snow on Runway(s)
PSR : Primary Secondary Radar
PSR : Primary Surveillance Radar
PSSA : Preliminary System Safety Assessment
PSSR : Present Secondary Surveillance Radar -code- 
PST : Project Supervision Team 
PSTN : Packed Switched Telecommunication Network
PSTN : Public Switched Telephone Network

Pt  : Total Pressure

PT : Point
PT : Portugal (ISO Country Code)

PTCHY : Patchy
PTE : POEMS Test Environment

PTH : Path

PTN : Procedure Turn
PTO : Preferred Time Over
PTOT : Provisional Take Off Time 
P- t - P / pt to pt : Point-to-Point
PTP : Part-Task Practice
PTRMC : Prototype Team Resource Management Courseware
PTS : PoinTS (route points)

PTS : Polar Track Structure
PTS : Pre-Training Screen 
PTSD : Post Traumatic Stress Disorder
PTT : Part-Task Trainer
PTT : Push to Talk
PTW : Project Team Work
PU : Processing Unit
PUB : Publications and Charts (AIS-TF)
PUMA : Performance Usability-Modelling of ATM
PV : Performance Verification
PV : Present Value
PVC : Permanent Virtual Circuit
PVD : Plan View Display

PVT : Private
PVT : GNSS Position Velocity Time

PWB : Printed Wire Board
PWG : Pensions Working Group
PWP : Physical Working Position
PWP : Published Way Point 
PWR : Power
PZ 90 : Parameters of Earth 1990
PZ : Portotroz (SI)




Q : Question
Q : Quadrature Component (MTI)
Q : Atmospheric Pressure
Q&A : Question and Answer
Q.23 : Signalling system for PABX
Q.SIG : ATS-Q.SIG - standard for ATC. G/G voice communications
QA : Quality Assurance (Section) CFMU/ENGD

QAR Quick Access Recorder
QAR : Quality Assurance Representative (DECADE)

QBI : Compulsory IFR Flight
QC : Quality Control (DECADE)
QCM : Quality Control Manager
QDM : Magnetic Heading (zero wind) (ICAO)
QDR : Magnetic Bearing (ICAO)
QF : Quality Factor 
QFE : Atmospheric Pressure at Aerodrome Elevation (or at runway threshold)
QFU : Magnetic orientation or runway in use
QHN : Altimeter Sub-scale setting (RLD paper)

QNE : Altimeter subscale set to 1013,2 hectopascals
QNF : Altimeter sub-scale setting to obtain elevation when on ground
QNH : Atmospheric Pressure at Nautical Height ; Q-code designation for atmospheric pressure at mean sea level

QOS : Quality of Service
QP : Quality Plan (MAS/DFS - ODS)
QPSK : Quadrature Phase Shift Keying
QRA : Who Are You

QRH : The barometric pressure as reported by a particular station
QRPS : Route Points Store (Static Data Bank)
QSIG : Signalling to a Q Reference Network
QTE : True bearing (ICAO)
QTG : Qualification Test Guid

QTY : Quantity  
QuestionAIR : Computer-based ATM questions bank

QUAD : Quadrant
QUIS : Questionnaire for User Interface Satisfaction




R : En-Route
r : Rate of change (climb or descent)
R : Red

R : Right (runway indentification)
R : Romania

R : Route Tuned NAVAID

R…: Radial (followed by a MAG track)

R…: Restricted area

(R) : Radar (radar service available)

R Team : Collection of air navigation charges under bilateral agreements with non-Contracting States
R&D : Research and Development

R/C Rate of Climb
R/T or RTF : Radio Telephony
R/T : Radio Telephonic Transmission
R+B : Range and Bearing line

R1 : Minor Repairs

R2 : Major Repairs
R2 : Eurocontrol Signalling Protocol
R2 : European signalling standard (Voice communication)
R2 : Signalling system used for telephone exchanges
RA : Radio Access
RA : Radio Altitude

RA : Rain (meteo)
RA : Resolution Advisory (ACAS/TCAS)
RA : Risk Analysis (TCAS)
RA : Routine Area

RAA : Regional Airline Association
RAARR : Radar Arrival

RAAS : Regional Area Augmentation System
RAC : Resolution Advisory Complement
RAC : RUHR Assistant Controller
RAC : Rules of the Air and Air Traffic Services-Control (ICAO)
RACE : Runway Capacity Enhancement
RAD : Radar

RAD : Radial

RAD : Radio

RAD : Route Availability Document
RADAC : Radar Verification Equipment in Norway
RADAR : Radio Detecting and Ranging
RADEP : Radar Departure
RADIN : Radar Data Interchange Network
RADIN : Radar Data Interface
RADNET : Radar Network (for interchange of radar data)
RADVIEW : Radar Verification Equipment in Norway
RAE : Royal Aerocraft Establishment (Farnborough)
RAF : Reference ATN Facility (US/Eurocontrol common project for development of the CAERAF)
RAF : Royal Air Force

RAFC : Regional Area Forecast Centre

RAG : Ragged
RAG : Range-Azimuth Gate Generator

RAG : Runway Arresting Gear
RAI : Italian Aeronautical Certification Authority

RAI : Runway Alignment Indicator

RAIL : Runway Alignment Indicator Lights
RAIM : Receiver Autonomous Integrity Monitoring (GPS)

RALT : name of enroute alternate aerodromes
RAM : Random Access Memory 

RAM : Reliability, Availability and Maintainability
RAM : Responsability Assignments Matrix
RAMBO : Reliable, Available, Maintainable, Benefits, Objectives

RAMOS : Remote Automatic Meteorological Observing System
RAMS : Reorganised ATC Mathematical Simulator 
RAN : Regional Air Navigation (meeting)
RANSU : Regional Air Navigation Service Unit (DFS)
RAP : Recognised Air Picture
RAP : Resource Allocation Process
RAPCON : Radar Approach Control Facility
RAPID : Recognised Picture Identification Distribution
RAPNET : (European) Regional Aeronautical Packet Switched Network (CBN + DAKOS)
RAPPI : Radar Access Plan Position

RAPS Recovery Access Presentation System
RAR : Restricted Area Requested
RARAD : Radar Advisory
RAS : Resource Allocation System

RASA : Radar Advisory Service Area
RASA : Requirements Analysis Strategy and Architecture Sub-group
RASC : Regional AIS System Centre
RASCAL : Radar Sharing Calculation
RASCAL : Radar Station Coverage Calculator

RASCAL Rotorcraft Air Crew Systems Concepts Airborne Laboratory
RASIF : Radar Simulator Flugsicherung
RASP : Radar Application Specialists Panel (MTPA / SSR)
RASP : Radar Surface Picture
RASS : Radar Analysis Support System
RASS-C : Radar Analysis Support System - Centre Level
RASS-P : Radar Analysis Support System - Plot data
RASS-PDP : RASS - Polar Diagram Measurement Facility
RASS-S : Radar Analysis Support System - Sensor Level
RASS-T : Radar Analysis Support System - Track data
RASTA : Radar Statistics Program
RASV : Responsibility Air Space Volume
RATE : Remote Air Traffic Services Terminal
RATS : Radar Analysis and Test System
R-ATSU : Air Traffic Service Receiving Unit
RATT : Radio Teletype
RB : Resque Boat
RBP : Radar Bypass Processor (MAS UAC)
RBS : Radio (Telephony) Backup System
RC : Radar Controller
RCA : Reduced Co-ordination Airspace

RCA : Reach Cruising Altitude

RCA : CFMU TERMINAL - Remote Client Application

RCAG : Remote Communication Air/Ground Facility

RCAT : Route Catalogue
RCC : Rescue Co-ordination Centre
RCD : DCL Request Message
RCDS : Radio Channel Distribution and Switching
RCDSS : Radar Control and Display Subsystem
RCF : Radio Communications Failure
RCFEP : Radar Data Communications Front-End Processor 
RCGSP : Review of the General Concept for Separating Panel (ICAO)

RCH : Reach or Reaching

RCHG : Repetitive Flight Plan Modification Message (ADEXP only)
R-Channel : Random Access Channel
RCL : Executive (i.e. Radar) Controller

RCL : Runway Centre Line

RCLL : Runway Centre Line Lights

RCLR : Recleared
RCM : Radar Co-ordinator (Controller) Message (Mil. ECM)
RCM : Statement of Basic Operation Requirement, Planning Criteria & Methods of Application (ICAO/AIS)

RCNL : Repetitive Flight Plan Data Cancellation Message (ADEXP only)
RCO : Reduce Cumulative Overloads
RCO : Remote Communications Outlet
RCO : Route Charges Office (National Route Charges Office)
RCP : Required Communication Performance

RCP : Radio Control Panel
RCR : Runway Condition Reading
RCRT : Refresh Cycle Response Time
RCS : Radar Cross Section
RCS : Remote Control System
RD : Risk Display (ODID)
RD : Routing Domain
RDC : Routing Domain Confederation
RD-Channel : Random Data Channel

RDDII : Radio Digital Distance Magnetic Indicator
RDF : Radio Direction Finding
RDG : Radar Data Generator

RDH : Reference Datum Height (for ILS)

RDI : Radio Direction Indicator
RDI : Routine Domain Identifier
RDIF : Radar Data Interchange Format

RDL : Radial
RDM : Running Display Message

RDO : Radio
RDP : Radar Data Processor
RDPP : Radar Data Post Processor
RDPS : Radar Data Processing System
RDQC : Radar Data Quality Control
RDR : Radar Data Recording
RDSS : Radar Determination Satellite System
RDTE : Research, Development, Trials and Evaluation

RE : Recent (used to qualify weather phenomena e.g. RERA = recent rain)

REA : Ready Message

REACT : Rain Echo Attenuation Compensation Technique
Real : Real time
Real-time FDMD : Real-time Flight Data Processing Management and Distribution
REC : Recall (ICAO) / Recording

REC : Receive or Receiver
REC : Request EOBT Change
RecDPS : Recording Data Processing System (PALLAS System)
REDAN : Spanish Data Network

REDL : Runway Edge Light(s)
REF : Reference
REFGHMI : Reference generic HMI

REG : Registration

REG : Regulatiion
REG : Regulatory (issues)

REGUL : Regulation

REIL : Runway End Indentifier Lights
REJ : Rejection Message

REJCTOT : Rejected Calculated Take-Off Time
REL : Release

RELCTD : Relocated
REM : Radio Emergency Module
REM : Roentgen Equivalent Man
REMOCO : Remote Control (Supervision System)
REMP : Radar Replacement and Modernisation Programme

RENL : Runway End Light(s)
REP : Report or Reporting

REP : Reporting Point

REQ : Request or Requested
RER : Rerouting
RER : Residual Error Rate

RERTE : Reroute
RES : Radar Environment Simulator
RESA : Runway End Safety Area (ICAO)
RESP : Response (ICAO)

RESPBY : Respond by (time out to give a response)
RESTQ : Recovery Stress Questionnaire

RESTR : Restriction

RESYNCING : Resynchronizing
RET : Airborne & ground retrofit (issues)
RET : Revised EOBT
RETD : Revised Estimated Time of Departure
REV : REVision / REVise (message)
RF : Radio Frequency
RF : Radius to a Fix (ARINC 424 Path Terminator)
RFCA : Panel on Route Facility, Cost Accounting and Cost Allocation (ICAO)
RFCP : Route Facility Costs Panel (ICAO)
RFEP : Radar Front End Processor
RFF : Radar Fall-back Facility
RFG : Radio Frequency Generator
RFI : Radio Frequency Interferences

RFI : Request For Information

RFI : Request For (direct) Improvement Message
RFL : Requested Flight Level
RFLT : Radio Frequency Unit
RFM : Remote Field Monitor
RFP : Replacement Flight Plan (Procedure)
RFP : Request for Proposal
RFPD : Repetitive Flight Plan Data
RFPS : Radar data Front Processing System (PALLAS system)
RFQ : Request for Quotation
RFS : Radar Fallback System
RFS : Random Field Sequencing
RFU : Radio Frequency Unit

RG : Range

RG : Varig Brasilian (airline)
RGCSP : Review of General Concept of Separation Panel (ICAO)
RGIC : Ranging Integrity Channel
RGS : Regional Ground Station
RGS : Remote Ground Station
RH : Radar Head

RH : Right Hand (turn)
RHCP : Right Hand Circular Polarisation
RHD : Radio (or Radar) Horizon Distance
RHEA : The Role of Human in the Evolution of Air Traffic Management

RHF : Ridiculously High Frequency
RI : Route Intercept
RIB : Routing Information Base
RIC : Radar Integration Control
RICE : RTF Interface Control Equipment
RID : Review Item Description
RIF : Radio Interface

RIF : Reclearance in Flight

RIF : changes of routing to the changed destination aerodrome and/or changed destination aerodrome (Flightplan)
RIG : Regional Implementation Group
RIMS : Ranging and Integrity Monitoring Station (GNSS-1/EGNOS)
RINAL : Portuguese Data Network
RIRT : Russian Institute of Radio Navigation and Time (St. Petersburg)
RIS : Relational Interface System
RISC : Reduced Instruction Set Computer
RISE : Retrieval and Interchange of Standards in Europe
RIT : RADNET Implementation and Integration Team
RITA : Replay Interface for TCAS Alerts

RITE : Right (direction or turn)

RJ : Roal Jordanian (airline)
RJC : Airspace Crossing Reject Message (Airspace Crossing Dialogue)

RJT : Rerouteing Rejection Message

RL : Report Leaving

RL : Runway Lights

RLA : Relay to
RLB : Rolling Ball
RLBCS : Rolling Ball CallSign (input)

RLCE : Request Level Change En-route

RLD : Rijks Luchtvaart Dienst (Dutch iquivalent of FAA)

RLG : Ring Laser Giro
RLIM : Radar Data Line Interface Module

RLLS : Runway Lead-In Light System

RLNA : Requested Level Not Available
RLP : Remote Line Printer

RLSD : Released
RLSM : Reduced Lateral Separation Minimum

RLST : Revised List (for RPLs)
RLW : Regie der LuchtWegen (NL) / Régie des Voies Aériennes (B) / Belgium Aviation Authority
RMA : Reliability, Maintainability, Availability
RMCD : Remote Master Control Desk
RMCDE : Radar Message Conversion and Distribution Equipment
RMCS : Remote Monitoring and Control System

RMI : Radio Magnetic Indicator
RMK : Remarks
RMM : Remote Maintenance Monitoring

RMNDR : Reminder

RMK : Remark(s)
RMP : Radio Management Panel
RMP : Required Monitoring Performance
RMPS : Radar Message Processing System

RMPs Radio Management Panels
RMS Error : Root Mean Square error.
RMS : Root Mean Square
RMSpv : RMS peak value.

RMU : Radio Management Unit

RNAV Area Navigation (generic acronym for any device capable of aircraft guidance between pilot-defined waypoints)
RNC : Required Navigation Capability
RNDSG : Route Network Development Sub-Group

RNG : Radio Range
RNLAF : Royal Netherlands Air Force
RNP : Required Navigation Performance
RNP5 : Required Navigation Performance 5
RNPC : Required Navigation Performance Capability/Criteria
RNPTF : Required Navigation Performance Task Force

RO : Tarom Romanian Air Transport (airline)
RO : Romania (ISO Country Code)
RO : Router Function

ROBEX : Regional OPMET Bulletin Exchange (scheme)
ROBIN : Road billing network
ROC : Rate of Change

ROC : Rate of Climb
ROD : Rate of Descent
ROF : Request on Frequency (Message)

ROFOR : Route Forecast (meteo)
ROI : Return On Investment
Role : Role-play
ROM : Read Only Memory (CD)
ROMATSA : Romanian Air Traffic Services Administration
ROMBULPO : Romania, Bulgaria and Poland

RON : Receiving Only
ROPA : RAPNET Operations and Planning Agreement
ROR : Range Only Radar
ROS : Route Orientation Scheme
ROSAS : Regional Organisation of the Sequencing and Scheduling of Aircraft System
ROSE : Rational Object oriented Software Engeneering
ROSE : Remote Operations Service Element

Router An ATN network layer gateway which performs the relaying and routing of data packets across interconnecting subnetworks based on the source and destination network layer addresses and the desired quality of network service
ROZ : Restricted Operations Zone
RP : Radar Post
RP : Reporting Point
RPC : Regional Planning Criteria
RPF : Rapid Prototyping Facility

RPK : Revenue Passenger-Kilometer
RPL : Repetitive Flight Plan
RPL : Stored Flight Plan

RPLC : Replace or Replaced

RPM : Revenue Passenger-Miles
RPM / rpm : Revolutions Per Minute
RPS : Radar Position Symbol
RPS : Recording and Playback System
RPT : Regular proficiency Training

RPT : Repeat or Repeated
RPU : Radar Processing Unit
RPV : Remotely Piloted Vehicle
RPVD : Radar Plan View Display
RPY : Replay

RQ : Air Engiadina (airline)
RQL : Request NOTAM List

RQMNTS : Requirements
RQN : Request NOTAM
RQP : Request for Flight Plan
RQP : Request Plan Message

RQP : CFMU/URB - Relations, Quality & Performance Team

RQRD : Required

RQS : Request Supplementary Flight Plan

RQS : Request Supplementary Information Message
RQT : ReQuesTing

RR : Report Reaching
RRA : Radar Recording Analysis

RRA : (or RRb, RRC etc. in sequence) delayed meteorological message
RRC : Recording Replay Computer 
RREC : Repetitive Flight Plan Recovery Message 

RRL : Runway Remaining Lights

RRN : Rerouteing Notification Message
RRP : Remote Radar Post
RRP : Re-routing Proposal Message
RRR : Radar data Recording and Replay system (RADNET / application software : COMSOFT)

RRTEREF : Reroute Reference

RRTES : Reroutes
RRU : Remote Radio Unit
RRV : Referred Revision Message 
RS NATS : Recruitment Services NATS
RS : NASC providing Regional Support (EAD)
RS : Radar System
RS : Reference Station
RSA : Radar Service Area
RSAP :  RMCDE Service Access Point
RSAP : Replenishment Spares Acquisition Program
RSC : Rescue Sub Centre

RSCD : Runway Surface Condition
RSFTA : Réseau de Service Fixe des Télécommunications Automatiques
RSG : Research Study Group
RSG : Route Structure Group
RSI : Radiation Status Indicator
RSLS : Receiver Side Lobe Suppression
RSM : Radar Service Message (RMCDE/ RADNET)
RSMC-Channel : Random System Management Control Channel
RSMTF : Radar Separation Minimum Task Force
RSO : Route per State Over-flown
RSOQ : Radar Stores Occupancy Query
RSP : Required System Performance

RSP : Responder Beacon
RSPD : Reported Speed
RSPL : Recommended Spare Parts List

RSR : En Route Surveillance Radar
RSRE : Royal Signals and Radar Establishment
RSS : Radar Separation Standard
RSS : Radar Sub-System
RSS : ROOT Sum Squared
RSSP : Radar Systems Specialist Panel
Rstd : Restricted (Time-Restricted Learning)
RSURTF : RASS-S Upper Requirements TF
RSUS : RPL Suspension Message

RSVN : Reservation
RSYD : Release Subject to Your Discretion
RT : Real Time

RT : Right Turn

RTA : Reduced Vertical Separation Minimum Transition Area

RTA : CFMU TERMINAL - Remote Terminal Access

RTA : Required Time of Arrival
RTB : Radar Tool Box
RTC : Radio Transmission Control
RTCA : A private, non-profit organization that brings industry and government together to address the needs of the worldwide aeronautical community. RTCA originally stood for Radio Technical Commission for Aeronautics.
RTCA : Requirements and Technical Concepts for Aviation. See also in Part II RTCA
RTD : Research and Development of Technologies

RTD : Delayed (used to indicate delayed meteorological message)

RTE  : Route
RTF or R/T : Radio Telephony
RTFM : Regulated Tactical Flight Model

RTG : Radio Telegraph

RTHL : Runway Treshold Light(s)
RTI : D-RVR Delivery Messge
RTIS : Road Travel Information Services
RTLS : Return To Launch Site
RTMDE : RADNET Test Monitoring and Demonstration Equipment (coulor screen)

RTN : Return or Returned or Returning
RTO : Ready for Take OffL : Reduced Take-Off and Landing

RTODAH : Rejected Take-off Distance Available, Helicopter
RTOS : Real Time Operating System
RTPTS : RouTe PoinTS
RTQC : Real Time Quality Control
RTQC/A : Real Time Quality Control / Assessment
RTR : D-RVR Request Message
RTR : Remote Transmission / Receiver
RTS : Real Time Simulation

RTS : Return to Service
RTSE : Reliable Transfer Service Element
RTSIM : Real-Time Simulation
RTT : D-RVR Termination Message
RTT : Ready to Task
RTT : Radiotletypewriter

RTZL : Runway Touchdown Zone Light(s)
RU : Russian Federation (ISO Countries Codes)

RUF : Rought
RUG : RASS Users Group

RUT : Standard Regional Route Transmitting

RV : Rescue Vessel
R-VKL : Radar (executive-) controller

RVSM : Reduced Vertical Separation Minimum of 300 m (1000 ft) between FL 290 and FL 410 inclusive.
RVR : Runway Visual Range

RVRM : Runway Visual Range Midpoint

RVRR : Runway Visual Range Rollout

RVRT : Runway Visual Range Touchdown
RVSM Entry Point : Reduced Vertical Separation Minima Entry Point
RVSM Exit Point : Reduced Vertical Separation Minima Exit Point
RVSM : Reduced Vertical Separation Minimum (in Europe)

RW : Runway
RWEWP : Runway End Way-point
RWIWP : Runway Intercept Way-point
RWY : Runway
RWY WP : Runway Waypoint
RX : Receiver Station




s : seconds

S : South
: Sweden

(S) : Secondary or Supplementary (frequency)

S/C : Step Climb
S1 : The future (desired) state

SA Degradation : Selective Availability degradation (of satellite signals)
SA : Salivary Cortisol

SA : Sand (meteo)
SA : Satellite
SA : Selective Availability (GPS)
SA : Separation Assurance
SA : Situational Awareness
SA : Skill Acquisition

SA : South African Airways (airline)

SAAM : System for Assignment and Analysis at a Macroscopic level (8.33 User Guide)

SAARU : Secondary Attitude/Air data Reference Unit
SAC : Source Area Code

SAC : Strategic Air Command
SAC : System Assisted Co-ordination
SACEUR : Supreme Allied Commander Europe
SACHA : Separation and Control Hiring Assessment 
SACLANT : Supreme Allied Commander Atlantic
SACON : Slovak Aeronautical Communication Network
SAD : System Architecture Document
SADIS : (Swedish) Satellite Distribution System
SADIS : Satellite Distribution of World Area Forecast System / ICAO Group
SAE : Society of Automotive Engineers

SAIFIR : System Iad for Integration and Fault Reporting (777)
SAF : EEC business area - support to safety monitoring
SAF : Safety (EATM domain)
SAFER : Safety and Errors
SAFI : Safety Monitoring for Indicators
SAI : System Architecture Interface
SAICO : Swedish Aeronautical Information Computer Aided system
SAL : Slot Allocation List 
SALADT : Screening Angle Analysis Digitised Terrain

SALS : Simple Approach Light System
SAM : Slot Allocation Message (CFMU - CASA)
SAM : South American Region
SAMHS : Spanish Aeronautical Messages Handling System

SAMPE : Society for the Advancement of Material and Process Equipment
SAMSO : US Air Force Systems Command / Space and Missile Organization (now Space Division)
SAMTF : Safety Assessment Methodology Task Force

SAN : Sanitary
SAN : Satellite Access Node
SANe : Skill Acquisition Network
SAP : Service Access Point

SAP :  as Soon as Possisble
SAPPHIRE : Satellite and Aircraft Database Programme for System Integrity Research
SAR : Search and Rescue
SAR : Stand-Alone Receiver
SAR : Synthetic Aperture Radar
SARP : Signal Automatic Radar Processing (NL)
SARPs : Standards and Recommended Practices (ICAO)
SARSAT : Search and Rescue Satellite Aided Tracking
SAS : Single Attachment Station (FDDI)

SAS : Scandinavian Airlines System

SAS : Scandinavian Airlines (airline)
SASKI : Name of an ATS Route reporting point
SASS : Surveillance Analysis Support System (ATC)
SASS-C : Surveillance Analysis Support System - Centre
SASS-S : Surveillance Analysis Support System - Sensor
SAT : Satellite(s)
SAT : Simulation Assessment Team
SAT : Site (System) Acceptance Test
SAT : Static Air Temperature
SAT : Systems Approach to Training
SATCAS : Selenia Air Traffic Control Automated System
SATCNS WG : Satellite CNS Work Group
SATCNS : Satellite Communications Navigation and Surveillance
SATCO : Signal Automatic Control
SATCOM : Satellite Communications
SATNAV GNSS : Satellite Navigation Sub-Group (NAVSEP TF)
SATORI : Systematic Air Traffic Operations Research Initiative (US)
SATS : Simulator System for Air Traffic Services
SATSA : Swedish ATS Academy
SAW : Surface Acoustic Wave Filter

SAWRS : Supplementary Aviation Weather Reporting Station

SB :Service Bulletin

SB : Southbound
SBAS : Space/Satellite Based Augmentation System

SBIR Small Business Innovative Research
SBR : Spaceborne Radar

SBR : Self Briefing
SBSR : Space Based Secondary Radar
SBT : Self Briefing Terminal
SBU : Service Business Unit
SC : Sector Co-ordinator
SC : Security Council (UN)
SC : Senior Controller
SC : Single Click (Mouse Input)
SC : Special Corridor
SC : Stack Controller
SC : Standing Committee (RTCA)

SC : Stratocumulus
SCAA : Slovenian CAA
SCAN : Swiss Data Network
SCAT : Supersonic Civil Air Transport
SCAT-1 Approach : Special Category 1 Approach
SCAT-1 : Special Category 1
SCATANA : Security Control of Air Traffic and Air Navigation Aids
SCATCC : Scottish Air Traffic Control Centre
SCC : Satellite Control Centre
SCDT : Selected Controlled Departure Times
SCEAP : Steering Committee for External Assistance Projects (decision DG)
SCEPC : Senior Civil Emergency Planning Committee
SCG : System Concept Group
SCIA : Simultaneous Converging Instrument Approaches
SCOATCC : Scottish Oceanic Air Traffic Control Centre
SCORS : Surveillance Concepts and Operational Requirements
SCP : Support Computer Programme
SCPC : Single Carrier per Channel
SCR : Scroll
SCRAD : Steering Committee for Research, Analysis and Development
SCRR : Service Central de Redevances de Route
SCS : Strategy Concept & System (EATM Unit)
SCSI : Small Computer-System Interface

SCT : Scattered (meteo)
SCT : Surveillance Coordination Team
SCTA : Service du Contrôle du Trafic Aérien (DGAC, DNA, France)
SCU : Satellite Communications Unit
SCU : Support CWP-Unit
SCV : Sub-Clutter Visibility
SD : Serial Dialling
SD : Specialist Domain
SD : Standard Deviation
SD'xx' : Specialist Domain `number'  
SDB : Static Data Bank

SDBY : Standby
SDD : Software Design Document
SDD : Synthetic Data Display
SDDLC : System Design and Development Life Cycle
SDE : Senior Director EATM
SDE : System Development Environment

SDF : Simplified Directional Facility
SDG : Sensor Data Generator
SDL : Standard Distribution List
SDLC : Synchronous Data Link Control procedures
SDLS : Satellite Data Link System
SDM : System Definition Manual (INMARSAT)
SDO : Selected Display Option (ODID)
SDO : Static Data Operations 
SDO : Supplementary Display Option
SDOE : Senior Director Operations and EATCHIP
SDP : Second Development Project
SDP : Simulator Development programme
SDP : Software Development Phase
SDP : Software Development Plan
SDP : Surveillance Data Processing (Sub-group CCT/EATCHIP)
SDPD : Surveillance Data Processing and Distribution
SDPDS : Surveillance Data Processing and Distribution System
SDPS : Surveillance Data Processing System (ICAO)
SDR : System Design Review
SDT : Stack Departure Time

SDT : CFMU/FMD - Support, Development & Training Section
SDTF : SYSCO Development TF
SDU : Satellite Data Unit
SDU : Static Data Update message
SDV : Simulator Development
SE : South-East
SE : Strategy Element
SE : Sweden (ISO Country Code)
SEAT : Site Equipment Acceptance Test

SEB : Southeast Bound
sec : Seconds
SECAM : Safety, Efficiency and Capacity in ATM Methodologies
SECRA : Secondary Radar

SECT : Sector
SEE : Software Engineering Environment
SEL : Sector List Window

SEL : Selected

SEL: Selcal code (Flightplan)
SELCAL : Selective Calling (System)
SELREL : Selective Release
SEM : Semmerzake
SEMP : Software Engineering Management Plan
SEP : Selective Employment Plan
SEP : Spherical Error Probable

SEQ : Sequence

SER : Service or Servicing or Served
SEROS : Semmerzake Radar Operating System (B / Military)
SES : Supplementary Equipment and Services

SESMA Special Event Search and Master Analysis

SESY : CFMU/DEVD - Service Systems Section
SEU : Software Engineering unit

SEV : Severe (used e.g. to qualify icing or turbulende reports)
SF : Finland
SF : Scaling Factor
SFACT : Service de la Formation Aéronautique et du Contrôle Technique
SFC : Surface (Ground Level / Sea Level)
SFD : Start Frame Delimiter

SFL : Sequence Flashing Lights
SFL : Supplementary Flight Level
SFLA : Assign SFL
SFMC : Sickness Fund Management Committee
SFOR : Stabilisation Force (Sarajevo)
SFPL : Short Flight Plan (FDPS)
SFPL : System Flight Plan Processing
SFT : Simplified Fast Time Simulations

SG : Snow Grains (meteo)
SG : Safety Group
SGAMI : Select Group for Assessing Manpower Issues
SGC : Swept Gain Control
SGCAS : Study Group on Certification of Automatic Systems

SGL : Signal
SGR : Study Group of the enlarged Committees for Route Charges (Eurocontrol)
SGS 85 : Sovietic Geodetic System

SH : Showers (meteo)
SHACC : SHAPE Airspace Coordination Centre
SHANDAP : Shannon Data Processing (System)
SHAPE : Supreme Headquarters Allied Powers Europe
SHAPE : Solutions for Human Automation Partnerships in European ATM
SHEL Model : Software - Hardware - Environment - Liveware Model
SHEL : Software, Hardware, Environment, Liveware
SHF : Super High Frequency
SHL : Saville and Holdsworth Ltd.
SHORAN : Short Range Navigation
SI : International System of Units
SI : Sector Indicator
SI : Selective Interrogator
SI : Situational Interview
SI : Slovenia, Republic of Slovenia (ISO Country Code)
SIA : Service d'Information Aéronautique
SIC : Sector Intercom (VCS)
SIC : Source Identification Code
SIC : Subject Indicator Code
SICASP : Secondary Surveillance Radar Improvements and Collision Avoidance System Panel (ICAO)
SICT : System Implementation Coordination Team
SICTA : Italian Consortium for the Applied ATM Research
SID : Standard Instrument Departure (Route)
SID/STAR : Standard Instrument Departure / Standard Arrival Route
SIDMET : Information issued by meteorological watch office
SIE : Standard Interface Equipment
SIF : Selective Identification Feature
SIGMA : Systemintegreging Gemensam Maskinvara (SE) / System Integration in Common Hardware
SIGMET : Significant Meteorological Information (broadcast warnings of weather hazards)

SIGWX : Significant Weather
SIL : Sector Inbound List Window
SIM : Simulator / Simulation(s) (EEC service)
SIM : Subscriber Identification Module
SIM-5 : Simulation Modernisation Project 
SIMM : Symbolic Integrated Maintenance Manual
SIMMOD : Simulation Model
Simul : Simulation

SIMUL : Simultaneous or Simultaneously
SIO : Sector Input Operator (MAS Ops Room)
SIOP : Society for Industrial and Organisational Psychology, Inc.
SIP : Slot Improvement Proposal Message 

SIR : Packed or Compacted Snow and Ice on Runway(s)
SIRO : Simultaneous Intersecting Runway Operations
SIROCCO : Study of the Impact of Revised Operational Concepts on the CNS/ATM ODP Model
SIS : English Standard for Documentation
SIS : Signal In Space
SIS : Special Information System
SISG : Safety Improvement Sub-Group
SIT : Slot Issue Time Parameter 
SIT : Software Integration Test
SIT : Subsystem Integration Test (DECADE)
SIT : System Integration Team 
SITA : Société Internationale de Télécommunications Aéronautiques (F) / Airline telecommunications and Information Service
SITAP : Simulator for Transportation, Analysis and Planning

SITATEX : Software developed by SITA
SITD : Systems Integration and Test Department

SITS : Subsytem Integration and Test Station

SIWL : Single Isolated Wheel Load
SJA : Strategic Job Analysis
SK : Slovakia, Slovak Republic (ISO Country Code)

SKC : Sky Clear (meteo)

SKED : Schedule, scheduled
SKIP : SKIP a sector

SL : Sea Level
SLA : Service Level Agreement
SLAP : Slot Allocation Procedures
SLAR : Side-Looking Airborne Radar
SLB : Side Lobe Banking
SLC : Side Lobe Cancellation

SLC : Slot Requirement Cancellation Message
SLI : Supplementary Level Inbound (ODID)
SLM : Standard Length Message (Mode S)
SLO : Supplementary Level Outbound (ODID)

SLOP : Strategic Lateral Offset Procedure
Slot : An arrival or departure time window reserved for a flight.

SLP : Speed Limit Point
SLR : Satellite Laser Ranging

SLR : Slush of Runway(s)

SLS : Satellite Landing System
SLS : Interrogation Side Lobe Suppression
SLT : Scheduled Landing Time
SLT : Slot Allocation
SLV : Statens Luftfartsvaesen (CAA/DK)
SLW : Sector Load Window
SLW : Selected Label Window

SLW : Slow
SM : Stack Manager
SMAA : Study for Mediterranean Area ADS
SMAE : Systems Management Application Entity
SMAN : Surface Management (APATSI)
SMART : Self-Managed Arrival Resequencing Tool
SMART : Simulator for Multi-radar analysis for realistic Trade / Traffic

SMART : Standard Modular Avionics Repair and Test

SMATSA : Serbia and Montenegro Air Traffic Services Agency Ltd
SMAW : Safe Minimum Altitude Warning
SMC : Station Monitoring and Control (RMCDE)

SMC : Surface Movement Control
SMC : System Monitoring and Computer / Control
SMC : Systems Management Concept
SMD : Storage Module Device
SMDE : Software Maintenance and Development Environment
SME : Subject Major/Matter Expert
SMEQ : Subjective Mental Effort Questionnaire
SMGC(S) : Surface Movement Guidance and Control (System)
SMHI : Swedish government owned (civil) MET Institute
SMI : Special Message Identifier (ACARS message Type B)
SMI : Stakeholder Relations Management and International Co-ordination
SMIDTS : Synthetic Movings Image Didactic / Tower Control Simulator (RLW/RVA)
SMITF : Safety Monitoring and Improvement Task Force
SMM : Safety Management Manual
SMM : Sector Monitor Message (RMCDE)

SMM : Slot Missed Message
SMR : Surface Movement Radar
SMS : Safety Management System
SMT : Station Management (FDDI / RMCDE)

SMT : Surface Mount Technology
SMTP : Simple Mail Transfer Protocol
SMX : Sub-Multiplexer

SN : Brussels Airlines (airline)
SN : System Notam

SN : Snow (meteo)
SN, S/N : Signal-to-Noise
SNA : Satellite Navigation Application
SNA : System Network Architecture (IBM Network)
SNAcF : Subnetwork Access Function
SNAcP : Subnetwork Access Protocol
SNASG, SNA-SG : Satellite Navigation Applications Sub-Group

SNBNK : Snowbank/s Caused by Plowing (Windrow(s))
SNDC : Subnetwork Dependent Convergence Function
SNDCF : Sub-Network Dependent Convergence Facility
SNET : Safety Nets

SNGL : Single
SNICF : Subnetwork Independent Convergence Function
SNIR, S/N : Signal-to-noise ratio
SNME : Subnetwork Management Entity
SNMP : Simple Network Management Protocol (RAPNET - CNG-)
SNOWTAM : A special series NOTAM notifying the presence or removal of hazardous conditions due to snow, ice, slush or standing water associated with snow, slush and ice on the movement area, by means of a specific pro forma.
SNPA : Subnetwork Point of Attachment
SNR : Signal-to-Noise Ratio

SO Southern Airways
SO : Specialist Objectives
SO : Standards Office (Eurocontrol)
So : The Present (undesired) state
SOC : Start of Climb
SOC : System / Sector Operations Centre
SOF : Stand-alone Operations Facility
SOGITS : Senior Official Group in IT Standardisation
SOIR : Simultaneous Operations on parallel (or near-parallel) Instrument Runways
SOL : Sector Outbound List (MDP)
SOP : Standard Operating Procedures

SOPA Standard Operating Procedure Amplified
SOR : State of Readiness

SOS : CFMU/ENGD – Systems Operations Section
SOTA : South Oceanic Transition area
SOW : Statement of Work

SP Space
sp : Ground Speed
SP : Service Provider
SP : Special Purpose (ASTERIX)
SP : Special point
SP : Standard Precision
SP : Succession Planning
SP : System Parameter

SPA : Slot Improvement Proposal Acceptance Message
SPACDAR : Specialist Panel on Automatic Conflict Detection and Resolution
SPAF : Strategic Performance Analysis and Forecast
SPAS : Sensor Performance Analysis Standard

SPD : Speed, Speed Mode
SPECI : Aviation Selected Special Weather Report

SPECIAL : Special Meteorological Report
SPF : Scratch Pad Field
SPG : Special Planning Group
SPI : Special Pulse (Position) Identification (SSR)
SPL : System Flight Plan / Supplementary Flight Plan
SPMP : Software Project Management Plan 
SPN : Short Plan Input
SPO : Special Project Office

SPO : Strategic Plan of Operation. See SPT

SPOC : SAR Point in Contact
SPORA : Specialist Panel on Operational Research and Analysis

SPOT : Spot Wind
SPR : Strip Printer
S-P-R-c : Stimuli, Processing, Response, controlled executive

SPS Sensor Processing Subsystem
SPS : Siemens Plessey Systems
SPS : Standard Positioning Service
SPS : STDMA/VDL Mode 4 Performance Simulator
SPSS : Statistical Package for the Social Sciences

SPT : Strategic Planning Team. The Strategic Planning Team acts as a focal point for the development of collaborative Strategic Plans of Operation.
sq. in. : Square Inch
sq-cm : cm

SQ : Singapore Airlines (airline)

SQ : Squalls (meteo)
SQE : Software Quality Engineer (DECADE)

SQL : Squall Line
SQL : Structured Query Language
SQS : Safety, Quality Management, and Standardisation (EATM Unit)
SQU : Squelch (VCS)
SR : Slovak Republic
SR : Study Report

SR : Sunrise

SR : Swissair (airline)

SR-30 : 30 Minutes before Sunrise
SRA : Surveillance Radar Approach

SRA : Special Rules Area
SRB : Solid Rocket Booster
SRC : Safety Regulation Commission (New Convention)

SRC : Systems and Research Center

SRD : Standard Route Document
SRD : System (or Software) Requirements Document
SRD : System Research and Development
SRDTF : System Research & Development Task Force
SRE : Slant Range Error
SRE : Surveillance Radar Element of GCA
SRG : Safety Regulation Group

SRG : Short Range
SRI : Stanford Research Institute
SRI : System Replay and Investigation

SRJ : Slot Improvement Proposal Rejection Message
SRM : Sector Revision Message
SRM : Slot Revision Message

SRP : Selected Reference Point

SRP : Slot Reference Point
SRP : Slot Revision Proposal (CFMU - CASA)
SRQ : Slot Request

SRR : Search and Resque Region
SRR : Slot Revision Request (CFMU - CASA)
SRR : System Requirements Review

SRS : Standard Routeing Scheme
SRS : System Requirements Specification
SRSG : Safety Regulation Sub-Group
SRT : Single Radar Tracker
SRT : Sort Route Transparent
SRU : Safety Regulation Unit (to support SRC). See SRC
SRU : Shop Replaceable Unit
SRV : Server

SRZ : Special Rules Zone

SS : Sand Storm (meteo)
SS : Sector Supervisor

SS : Sunset

SS+30 : 30 Minutes after Sunset
SSA : Smallest Space Analysis
SSA : System Safety Assessment

SSALF : Simplified Short Approach Lighting with Sequence Flashers

SSALR : Simplified Short Approach Lighting with Runway Alignment Indicator Lights

SSALS : Simplified Short Approach Lighting Systerm
SSAP Selector : Session Service Selector
SSAP : Source Service Access Point (RMCDE / RADNET)
SSB : Single Side Band
SSD : Synthetic Situation Display
SSDD : System/Segment Design Document
SSDG : Surveillance Strategy Drafting Group

SSE : South-South-East
SSE : Sum of Squared Errors
SSEC : Static Source Error Correction

SSFDR Solid-State Flight Data Recorder
SSGHI : Surveillance Sub-Group on Harmonisation and Implementation
SSGS : Surveillance Sub-Group on Standards
SSGT : Surveillance Sub-Group on Tools

SSM Sign Status Matrix
SSM : Standard Schedules information Manual 
SSM : System Surveillance and Maintenance
SSO : STAR Support Office
SSP : Secondary Spare Part
SSP : Sole Source Procurement
SSP : Source Selection Panel  
SSPA : Solid State Phased Array
SSPSG : Structures for Service Provision Sub-Group (High Level Group: Single European Sky (EU)
SSR Mode S : Selective Address SSR
SSR : Secondary Surveillance Radar
SSR : Software Specification Review
SSR : Solid State Relay
SSRBRIGH : Highlight set code to target (input)
SSRC : Current SSR Code
SSS : Source Select Switch 
SSS : System/Segment Specification
SSSP : EU Subgroup on Structures for Service Provision (see SSPSG)
SST : Supersonic Transport
SSTS : Space Surveillance and Tracking System
S-SUP : Sector Supervisor

SSW : South-South-West
ST : Specialist Task

ST : Stratus
ST, S/T : Short-Term
STA : Sequence / Scheduled Time of Arrival 
STA : Straight in Approach

STAB Stabilizer
STAC : Second Time Around Clutter
STANAG, Stanag : Standardisation Agreement 
STANINE : Standard Nine Score
STANLY : Statistics and Analysis
STANS : Simulation facility of a Total Air Navigation System
STAR : Second Time Around Returns (Radar)
STAR : Self Test and Repair
STAR : Sistema Telegráfico Automático de Retransmissão (PoAF) (PT) / Standard (instrument) Arrival Route
STAR : Standard Terminal (Instrument) Arrival Route
STAR : Studies, Tests and Applied Research (former STT)
STAR : Surface to Air Recovery
STARS : Surveillance and Tracking Attack Radar System
START-OVER : Process of putting in action the COLD-STANDBY
STAT : Second-Time-Around Targets
STAT : Statistics
STATFOR : Specialist Panel on Air Traffic Statistics & Forecasts
STB TF : Short-Term Benefits Task Force
STC : Sensitivity Time Control
STC : SHAPE Technical Centre (NATO, Hague)
STC : Short Time Constant
STC : Simulation Technical Coordinator
STC : Steering Committee

STC : Supplemental Type Certificate (FAA)
STCA : Short-Term Conflict Alert ; a ground-based safety net
STCD : Short-Term Conflict Detection
STCW : Short-Term Conflict Warning
STD : Scheduled Time of Departure 
STD : Software Technical Designer
STD : Standard (altimeter setting)
STDMA : Self-organising Time Division Multiple Access
STEP : Social, Technological, Environmental and Political

STF ARTAS, STFAD : Surveillance Task Force on ARTAS Development
STF : Selection Task Force

STF : Stratiform
STFAP : Surveillance Task Force on the Appraisal Programme
STFDPPAS : Surveillance Task Force on the Data Processing Performance Analysis Standard
STFRDE : Surveillance Task Force on Radar Data Exchange
STFRL : Surveillance Task Force on Reference Levels
STFRSS : Surveillance Task Force on the Radar Surveillance Standards
STFSDIR : Surveillance Task Force on Surveillance data Distribution Infrastructure Requirements
STF-SDPS : Surveillance Task Force on Surveillance Data Processing Systems
STFSPAS : Surveillance Task Force on the Sensor Performance Analysis Standard
STFTE : Special Task Force of Training Experts
STFTV : Surveillance Task Force on Transponder Verification
STG : Eurocontrol Standards Group . See SSGS
ST-ICD : Short-Term Interface Control Document
STLP : ATS Selection Training and Licensing Panel

STMP : Special Traffic Management Program.

STN : Station

STNR : Stationary
STOA : Scientific and Technological Options Assessment
STOL : Short Take Off and Landing
STORIA : Simulation Tool for Online Recording and Analysis
STP : Shielded Twisted Pair or Software Rest Plan
STP : Software Test Plan (MAS/DFS - ODS)
STP : Standardised Training Package
STPV : Service du Traitement automatique des Plans de Vol (F-FPPS)
STR : Service du Traitement des données Radar (F-RDPS)
STR : Software Test Report  
STRANGE : Simplified Trajectory Generator
STRAT : Strategic Planning System 
STRATPLAN : CFMU Strategic Planning Meeting 
STS : Stand-by Telephone System

STS : Status (Indicator)

STS : Reasons for special handling: (Flightplan)


STS/EMER Flights engaged in emergency missions

STS/EXM833 State aircraft, not equipped with 8.33 kHz channel spacing radio equipment prescribed for an area

STS/HEAD Flights with Heads of States

STS/HOSP Flights with sick or injured persons needing immediate medical assistance, including flights urgently required for life-saving medical care of sick or injured persons. This comprises both flights for the transport of transplants, stored blood and medicine and flights to be conducted to pick up a patient, transplants, stored blood or medicine at the destination place

STS/HUM Flights operating for humanitarian reasons

STS/NIL Replaces all other STS/entries. Only to be used when reporting flight plan changes\

STS/NONRNAV State aircraft, not equipped with type RNP prescribed for a route segment, a routing and/or an area

STS/NONRVSM State aircraft without RVSM permission

STS/PROTECTED Flights critical to safety, the flight plan of which is only to be made available to a limited circle of recipients

STS/RNAVINOP For aircraft, the RNAV equipment of which is inoperable at short notice or no longer complies with the required minimum conditions

STS/SAR Flights engaged in Search and Rescue missions

STS/STATE Government flights
 : Support to States (Eurocontrol)
STSMOD : Delay ac (input)
STT : Studies, Tests and Trials (now : STAR)

STTR Small Business Technology Transfer Resources
STU : Selected Trajectory Update
STUD : Innovative studies (ARDEP)

STWL : Stopway Lights

SU : Aeroflot (airline)
SUA : Special Use Airspace
SUATMS : Single Unified ATM System

SUBJ : Subject to
SUC : Start-Up Controller
SUCT : Surveillance analysis and Calibration Tools (ARDEP)
SUDP : Surveillance data Processing (ARDEP)
SUMI : Software Usability Measurement Inventory
SUP : Supervisor
SUP : Supplement
Sup. Pract. : Supervised Practices
SUP/ACC : Supervisor Area Control Centre
SUP/APP : Supervisor Approach
SUP/MIL : Supervisor military
SUPPS : Regional Supplementary Procedures (ICAO)
SUPSIS : Supervisor (Centre and System)
SUR : Surveillance (EATM Domain)
SURT : Screen Update Response Time
SURT : Surveillance Team
SurvITE : Surveillance Integrated Tested for EATMS
SV : Secure Voice
SV : Space Vehicle (Satellite)
SVC : Service (message)
SVC : Switched Virtual Circuits (RMCDE / SIR)

SVCBL : Serviceable
SVFR : Special VFR
SVID : System V Interface Definition

SVN : Satellite Vehicle Number
SVP : Supervisor

SVRWX : Severe Weather
SVS : Synthetic Vision System
SVVP : Software Verification and Validation Plan 
SW : South-West
SW, s/w : Software
SWAP : Severe Weather Avoidance Procedure (Program)
SWAT : Subjective Workload Assessment Technique

SWB : Southwest Bound

SWEPT : Swept or Broom(ed)
SWCI : Software Configuration Item  
SWG : Simulation Working Group
SWI : Swisscontrol Interface
SWIFT : Specifications for Working positions In Future Air Traffic Control
SWIM : System-Wide Information Management

SWM : SIP Wanted Message
SWORD : Subjective WORkload Dominance technique
SWOT : Strength, Weaknesses, Opportunities and Threats
SWP : Software Simulation Package
SWP : Support Working Position 
SWS : Software Service
SWY : Stopway (ICAO)
SXCOP : Sector Exit Coordination Point
SY : Syrian Arab Republic (ISO Countries Codes)
SYCA : System Capacity
SYCO : System Configuration
SYMA : System Manager
Sync. : Synchronous
SYSCIMIC : System supported Civil/Military Coordination
SYSCO : System Supported Coordination
SYSEVAL : System Evaluation
S (Sigma) : Symbol for sum
s (small sigma) : Symbol for Standard Deviation




t  : Tons

T : Tesla / Terminal

T : Temperature
t.b.d. : To be decided / discussed

T/C :Top-of-Climb

T/D :Top of-Descent

T/O :Takeoff
TA : Task Analysis
TA : Test Area

TA : Time of Arrival
TA : Traffic Advisory (ACAS/TCAS)
TA : Transition Action
TA : Transition Altitude
TAA : Terminal Arrival Area
TAA : Track Accuracy Analysis
TAAM : Total Airspace and Airport Modeller (Preston Group, Victoria, Australia)
TACAN : UHF Tactical Air Navigatoion aid (Azimuth and DME)

TACH Tachometer
TACIS : Technical Assistance to the Community of Independent States ( EC )
TACOT : TACT Automated Command Tool
TACOT : Tactical Operational Tool
TACT data : Data required by or output by the CFMU TACT system.
TACT : CFMU Tactical Computer System
TACT : Tactical Flow Management Working Position
TAD : Target Audience Description
TADIL : Tactical Distribution List
TAF : Terminal Area (Aerodrome) Forecast
TAFEI : Task Analysis For Error Identification
TAG : Transitional Airport Group (APATSI)
TAI : International Atomic Time

TAI Thermal Anti-lce

TAIL : Tail (wind)

TAIS : Total Aircraft Information System
TALK : (Swedish) VCS Upgrade Programme / System
TAM : Technical Acknowledgement Message

TAMS : Total Airport Management System
TAMP : Turkish ATC Modernisation Project
TAOIT : Tribunal Administratif de l'Organisation Internationale du Travail

TAP Terminal Area Productivity
TAR : Terminal Area (surveillance) Radar
TAR : Trials ATN Router
TARA : Terminal Area RNAV Applications Task Force
TARAD : Tracking Asynchronous Radar Data
TARE : Telegraphic Automatic Relay Equipment
TARTAR : ATS Route Structure between Armenia, Azerbaijan, Georgia, Iran, Turkey
tas / TAS : True Airspeed
TAS : Traffic Advisory System
TASC : (Industry) The Analytical Science Corporation

TAT : Total AirTemperature
TATCA : Terminal ATC Automation (FAA)
TATCI : Tallinn ATC Improvement project (Estonia)
T-ATSU : Transferring ATS Unit (ICAO)
Tau : Range / Range rate (TCAS)

TAWS : Terrain Awareness and Warning System

TAX : Taxi or Taxiing
TB : Tellback
TBA : Tellback Area
TBA : To Be Advised
TBD : To Be Determined (Defined)
TBN : To Be Notified
TBS : Telephone Back-up System (VCS)

TBO Time between Overhauls

TBS To Be Specified

TC : Typical Changes
TC : Tactical Controller
TC : Transit Corridor
TC : Transition Concept

TC : Tropical Cyclone
TC/OC : Technical Control and Operational Control
TCA : Terminal Conflict Alert

TCA Terminal Control Area
TCA : Track Continuity Area
TCA : Track-to-chain Association
TCA : Traffic Count Area 
TC-APD : Tactical Controller Activity Predictor Display
TCAS : Traffic Alert and Collision Avoidance System
TCB : Training Co-ordination Board (Eurocontrol, IANS)
TCC : Thrust Control Computer
TCC : Traffic Control Centre
TCDP : Technical Control Data Processor
TCG : Training Consultation Group / Groupe consultatif sur la formation
T-Channel : Time Division Multiple-Access Channel
TCL : Terminal Control
TCOP : Transfer Coordination Point
TCP / IP : Transmission Control Protocol / Internet Protocol
TCP : Transmission Control Protocol
TCPU : Touch Panel Central Processing Unit (ACS)
TCT : Technical Control Terminal

TCU : Towering Cumulus (meteo)
TCWP : Threshold Crossing Way-point
TDA : Track Detection Analysis
TDB : Track Data Block
TDCE : Telephone Distribution and Control Equipment
TDCP : Test Display and Control Panel
TDD : Time Division Duplex
TDF : Total Delayed Flights
TDF : Training and Development Facility
TDH : Training Development and Harmonisation (IANS)
TDM : Time Division Multiplexing
TDM : Total Delay in Minutes
TDMA : Time Division Multiple Access

TDO : Tornado
TDOP : Time Dilution Of Precision
TDR : Target Data Receiver
TDR : Track Drop Rate
TDR : Traffic Data Record
TDS : Tactical Data System
TDS : Test and Development Sector
TDSP : Training Documentations and Special Projects
TDWR : Terminal Doppler Weather Radar (TDWR located and classifies windshear conditions and provides advisories in the terminal area. These data are available through the DLP.)
TDZ : Touchdown Zone

TDZL : Touchdown Zone Lights

TDZ LGT : Touchdown Zone Lights

TE : Time of Entry

TE : Lithuanian Airlines (airline)
TEC : Technical ATM Systems and Logistics Support
TEC : Total Electron Content
TEC, TECH : Technical

TECR : Technical Reason
TEL : Telephone
TELIA : (Swedish) Telecommunications Provider

TEMP : Temperature
TEMP : Test and Evaluation Master Plan

TEMPLE : Terminal Management and Planning Equipment

TEMPO : Temporary or Temporarily
TEN : Trans-European Network

TEND : Trend Forecast
TEN(-T) : Trans European Network (-Transport) (European Commission funding)
TEPS : Trajectory Editor and Problem Solver

TER : Terminated
TERPS : Standard for Terminal Instrument procedures 
TES : Trials End System project
TF : Task Force or Touch Field (VCS)
TF : Track to a Fix (ARINC 424 Path Terminator)
TFA : Test Flight Analysis
TFACS : Task Force on Assessment Centre Standards

TFC : Traffic
TFCCC : Task Force Common Core Content .
TFD : Thin Film Diode
TFDATS : Delegation of ATS Task Force (ANT)
TFIS : Traffic Flow Investigation System

TFM Traffic Flow Management

TFMS : CFMU/ENGD - Technical Facilities & Management Support Section

TFR : Temporary Flight Restriction
TFR : Tactical Flight Record 
TFT : Thin Film Transistor
TFTR : Terrain Following Training Route
TFTS : Terrestrial Flight Telephone System
TF-TTM : TF on Technology Based Training Tools and Methods
TFV : Traffic Volume

TG : Thay Airways (airline)
TG : Task Group
TGDLP : Trials Ground Data Link Processor
TGF : Traffic Growth Factor 
TGL : Temporary Guidance Leaflet (JAA)

TGL : Touch and Go Landing

TGT : Target

TGS : Taxiing Guidance System
TH-CSF : Thomson CSF
THD : Total Harmonic Distortion

THDG : True Heading

THN : Thin

THR : Threshold

THR : Thrust

THRL : Treshold Lights

THRU : Through
TIA : Traffic Information Area

TIAS : True Indicated Airspeed
TICTAC : Time Constrained Trajectory Computation : Trajectory predictor
TID : Touch Input Device
TIDE : Tactical and IFPS Development Environment
TIDmn : Track Initiation Delay Mean
TIDsd : Track Initiation Delay Standard Deviation

TIL : Until
TIM : Transfer Initiation Message
TIMERS : Traffic Intelligence for the Management of Efficient Runway Scheduling

TIP : Until past….(place)
TIP : Touch Input and Display Panel

TIS : Time to Insert the Sequence
TIS : Traffic Information Service or Sector

TITLE : Message Name
TIZ : Traffic Information Zone

TK : Turkish Air (airline)

TKE TrackAngle Error

TKOF : Take-off
TKX : Crosstell Tracker

TL : Tans Mediterranean Airways (airline)
TL : Transition Line (Level)
TL : Traverse Level

TL… : Until (meteo)
TLA : Title Line Area

TLOF : Touchdown and lift-off area
TLPD : Traffic Load Prediction Device
TLS : Tactical Load Smoother
TLS : Target Level of Safety
TLV : Type Length Value
TLX : Task Load Index (NAA)

TM : Traffic Management
TMA : Terminal Manoeuvring Area ; Terminal Control Area (ICAO)

TMA : Traffic Management Advisor
TMA-TC : TMA Tactical Controller
TMC : Technical Monitoring and Control
TMC : Terminal Control Centre

TMC : Thrust Management Computer  
TMCS : Technical Maintenance and Control System
TMCS : Technical Monitoring and Control System (RMCDE / MADAP)
TMCU : Tower Main CWP Unit

TMF : Thrust Management Function

TMPA : Traffic Management Program Alert
TMRR : Temporary Minimum Disk Route
TMS : TeleManagement System
TMS : Tools Manager Server
TMS : Traffic Management System
TMSSG : Top Management Structure Sub-Group
TMU : Traffic Management Unit (FAA)
TN : Track Number
TN : Trajectory Negociation
TN : True Negative

TN True North
TN : Tunisia (ISO Countries Codes)

TNA : Turn Altitude
TNAV : Time Navigation

TNH : Turn Height

TO : Takeoff
TO : Technical Order

TO : Time Over

TO : To…(place)
TOA : Terms of Agreement
TOAST : Team Oriented ATC Simulator Training
TOAST : Technical, Operational and System Tests
TOC : Technical Operators Centre
TOC : Top Of Climb
TOC : Transfer Of Control
TOD : Top Of Descent
TODA : Take Off Distance Available (ICAO)

TODAH : Take Off distance available, helicopter

TOGA : Takeoff/Go-Around

TO EPR Takeoff Engine Pressure Ratio

TO Nl Takeoff Engine Fan Speed

TOP : Cloud Top
TOPL : Take Off Performance Limits
TOR : (Swedish) Briefing System (MET, Flight Plans)
TOR : Terms Of Reference
TORA : Take Off Run Available
TORCH : Technical, Economical and Operational Assessment of an ATM Concept Achievable from the Year 2005
TOS : Traffic Orientation Scheme
TOSCA : Testing Operational Scenarios for Concepts in ATM

TOT : Take-Off Time
TOT : Time Over Target

TOT : Total
TOWP : Take Off Waypoint

TP : TAP Air Portugal
TP : Trajectory Prediction ; Transport Protocol
TP : Turning Point
TP : True Positive
TP-4 : Transport Protocol, class 4
TPAS : Trajectory Predictor based Aircraft Simulator
TPD : Transition Programme Description 
TPDR : Transponder
TPDU : Transport Protocol Data Unit (RMCDE)
TPINS : Transition Plan For The Implementation Of The Navigation Strategy
TPL : Task Priority List
TPL : Transport Layer
TPS : A mono-radar track format
TPT : Touchdown Point
TQM : Total Quality Management
TR : Test Report

TR : Track

TR : Transbrasil (airline)
TR : Turkey
TRA : Required Time for Arrival
TRA : Temporary Reserved Airspace/Area
TRA : Traffic (type)

TRA : Thrust Reduction Altitude
TRACON : Terminal Radar Approach Control  
TRAINDEV2 : Integrated Eurocontrol Training Design Tool
TRAMON : Traffic Monitoring

TRANS : Transition or Transmit or transmitter
TRANSCOM : French public telecommunication network
TRAP : Technical Review and Audit Plan 
TRB : Tracker Ball
TRB : Transportation Research Board (4-States)
TRD : Transit Routing Domain
TREE : Transit Radiation effects on Electronic Equipment
TREN : Transport and Energy (General Directorate EU)
TRF : Total Regulated Flights
TRG : Training
TRK : Track (to a NAVAID)

TRL : Transition Level
TRM : Team Resource Management

TRML : Terminal
TRMTFII : Team Resource Management Task Force II

TRNG : Training
TROL : Tapeless, Rotorless On Line

TROP : Tropopause
TRP : Thrust Rating Panel
TRR : Test Readiness Review (MAS - ODS)

TRS : Time to Remove from the Sequence
TRSB : Time Reference Scanning Beam

TRSN : Transtition

TRU : True
TRUST : Terminal Routes Using Speed-Control Techniques (MITRE, CAASD)
TRY/PFL : Try Input of Planned Flight Level
TS : Technical Specification
TS : Technical Supplement
TS : Test Specification

TS : Thunderstorm (meteo)
TS : Track Server 
TS : Transport Service User
TSA : Temporary Segregated Area
TSAP : Transport Service Access Point
TSCU : Tower Support CWP Unit
TSD : Time Sequence Diagram
TSD : Traffic Situation Display (FREER)
TSDD : Test Synthetic Dynamic Display
TSDF : Time Slot Duty Factor
TSDG : Technical and System Development Group
TSE : Total System Error
TSG : Training Sub-Group
TSGE : Tri-Service Group on Communications and Electronics 
TSIKADA : Russian four-satellite civil navigation system.
TSIKADA-M : Russian six-satellite military navigation system

TSNT :Transient
TSO : Technical Service/Standard Order
TSO : Time Sharing Option
TSP : HRS Training Sub-Programme (EATM)
TSR : Terminal Surveillance Radar
TSr : Track Swop Rate
TSRV : Transport System Research Vehicle (Facility)
TSS : Target Software Server
TSS : Traffic Sub-System
TST : Test
TST : Trajectory Support Tool

TSTMS : Thunderstorms
TSU : Technical Support Unit

TT : TeleTypewriter

TT : Total Temperature
TTA : Tactical Training Area
TTC : Telemetry and Telecommand Centre
TTF : Total Flights

TTG : Time To Go
TTL : Transistor-Transistor Logic
TTP : TCAS II Transition Program
TTR : Target Tracking Radar

TTS : Time To Station
TTS : Trails Transport Service (ATN)

TTW : Time To Waypoing
TTY : Teletype Telex Machine

TU : Tunis Air
TU : Temps Universel
TU : Turkey
TUM : Time Update Message

TURB : Turbulence
TV : Television
TVE : Total Vertical Error

TVOR : Terminal VOR
TWDL : Two-Way DataLink
TWG : Training Working Group
TWI : Terminal Weather Information
TWIP : Terminal Weather Information for Pilots
TWN : Tactical Weather Network
TWP : Technical Work Programme in the Air Navigation Field (ICAO)
TWR : Tower Control Unit (Aerodrome Control Tower)
TWS : Technical Watch Supervisor
TWS : Terminal Weather Service (ICAO)
TWS : Track While Scan
TWT : Travelling Wave Tube

TWY : Taxiway

TWYL : Taxiway Lights
TX / RX : Transmitter / Receiver (Radar head)
Tx : Next waypoint ETA

Tx : Teletype
TX : Transmitter Station
Txt : Text
TXWY : Taxy Way
TYP or TYPE : Aircraft Type

TYPH : Typhoon
t (Tau) : Symbol for time




U : Upward (tendency in RVR during pervious 10 minutes)

U/L : Upper / Lower - Upper Link

U/S : Unservicealble
UA : Ukraine (ISO Countries Codes)

UA : United  Airlines (airline)

UAB : Until Advised By
UAC : Upper Area Control (Centre)
UACC : Upper Airspace Control Centre
UAP : User Application Profile (RMCDE)

UAR : Upper Air Route
UAS : Upper Airspace
UAV : Unmanned Aerial Vehicle
UCDU : Universal Control and Display Unit
UDA : Upper Advisory (Service) Area
UDF : Ultra High Frequency Direction Finding

UDF : Unducted Fan
UDRE : User Differential Range Error
UEATMS : Uniform European Air Traffic Management System
UEO : Union de l'Europe Occidentale / Western European Union (=WEU)
UERE : User Equivalent Range Error
UFF : Ultimate Fallback Facility
UFN : Until Further Notice
UFO : Unidentified Flying Object

UHDT : Unable Higher Due Traffic
UHF : Ultra High Frequency
UIC : Unit Identity Code
UIC : Upper Information Centre
UIECS : Union of International and European Civil Servants
UIMS : User Interface Management System
UIR : Upper (flight) Information Region
UIVE : User Ionospheric Vertical Range

UK : Air UK (airline)
UK : United Kingdom (ISO Country Code)
UKAATS : UK Advanced ATS
UKD : Upgrade ZKSD and coupling with DERD-X
Ukraviatsia : Ukrainian State Aviation Administration
UkSATSE : Ukrainian State Air Traffic Services Enterprise

UL : Air Lanka (airline)

UL : Ultra Light glider
UL : Upper Link (ATS route indication) or Uplink

ULM : Ultra Light Motorized

ULR : Ultra Long Range
UMA : Unmanned Aircraft

UNA : Unable

UNAP : Unable to Approve

UNAVBL : Unavailable
UNHCR : United Nations High Commissioner for Refugees
UNINC : Unusual Incidents
UNL : Unlimited

UNLGT : Unlighted

UNMKD : Unmarked

UNMNT : Unmonitored

UNO : United Nations Organization

UNREL : Unreliable

UNT : Until

UNUSBL : Unusable

UPD : Update Plan Divergence
UPP : Upper airspace
UPS : Uninterrupted Power Supply / System
UPSEL : Update Selection
URA : User Range Accuracy
URANIA : UpRading Athens Terminal Area aNd Interfacing to the PALLAS ACC system

URB : CFMU – User Relations Bureau
URD : User Requirements Document
URE : User Range Error
URET : User Request Evaluation Tool (MITRE Conflict Detection product)
URG : Urgency (ICAO)
URP : User Requirements Phase
URTF : User Requirements Task Force

USAF : US Air Force
USAREUR : US Army (Representative) in Europe
USART : Universal Synchronous / Asynchronous Receiver/Transmitter
USCG : United States Coast Guard
USD : US Dollar
USFSPEI : Union Syndicale Fédérale of the European and International Public Services
USG : US Government
USNO : US Naval Observatory
USSPE : Union Syndicale - Service public européen / European Public Service Union (=EPSU)
UT : Universal Time
UTA : Upper (Traffic) Control Area
UTA : Upper Transition Area
UTC : Universal Time Co-ordinates
UTP : Unshielded Twisted Pair
UUP : Updated (Airspace) Use Plan
UVA : Utility Value Analysis


V : Velocity

V : Volt

V1 : Take-off decision speed

V2 : Minimum take-off safety speed at 35’
V&V : Validation & Verification
V/M : Volts-per-meter

V/S : Vertical Speed/Vertical
V/STOL : Vertical or Short Take-Off and Landing
Vx : Version x
VA : Heading to an Altitude (ARINC 424 Path Terminator)

VA : Design Maneuvering Speed

VA : Vulcanic Ash (meteo)
VAA : Value Added Applications 
VAC : Volts, Alternate Current

VAC : Visual Approach and Landing Chart
VAFOR : Very Advanced Flight Data Processing System Operational Requirement
VAFORIT : VAFOR Implementation

VALFAC : Validation Facility (avionics test and simulation facility)
VAN : Value Added Network
VAP : Visual Aids Panel
VAP : Volumetric Airspace Penetration
VAPS : Virtual Applications Programming Software

VAPS : Visual Approaches
VAQ : VHF Avionics Qualification

VAR : Variation Magnectic

VAR : Volt-amps Reactive
VAR : VCS, Ancillaries and Remote control system

VAR : Visual-aural Radio Range
VAS : Vienna ATCC Data Processing System
VAS : Vortex Advisory System
VASI : Visual Approach Slope Indicator

VASIS : Visual Approach Slope Indicator System
VAT : Value Added Tax
VAW : Vertical Assistance Window (ODID)

VBF(LO) : Flaps up minimum buffet speed at current maneuver load factor minus altitude dependent variable
VBX : Visual Basic Extensions

VC : Design Cruising Speed

VC : In Vicinity (meteo)
VC : Virtual Circuit

VD : Design Diving Speed

VD : Heading to a DME distance

VDC : Volts, Direct Current
VDEV : Vertical Deviation
VCCS : Voice Communication and Control System
VCI : Voice Change Instruction, a message of the ACM service

VCMAX : Active Maximum Control Speed

VCMIN : Active Minimum Control Speed
VCO : Voltage Controlled Oscillator

VDP : Visual Descent Point
VCR : Visual Control Room
VCRI : Verification Cross Reference Index 
VCS : Voice Communications System
VCSS : Voice Communications Switching System
VCSTF, VCS-TF : Voice Communications System Specification Task Force

VCY : Vicinity
VD : Heading to a DME Distance (ARINC 424 Path Terminator)
VD : Vertical Dispersal
VDC : Direct Current Voltage
VDF : Very high frequency Direction Finding station
VDF : VHF Direction Finder

VDGS : Visual Docking Guidance System
VDL : VHF Digital/Data Link
VDL/4 : VHF Self-organising TDMA (STDMA) Data Link Mode 4
VDOP : Vertical Dilution Of Precision

VDR : VHF Data Radio

VER : Vertical
VHFAMS : Very High Frequency Aeronautical Mobile Services
VDR : VHF Digital/Data Radio
VDU : Video (Visual) Display (Distribution) Unit
VDX : Videotext
VEL : Velocity Leader
VENSIM : Ventana Simulator
Ver : Vertical
VESDA : Very Early Smoke Detection Apparatus (Fire alarm system)
VF : Voice Frequency

VFE : Flaps Extended Placard Speed
VFOP : Visual Flight Rules Operations Panel
VFR : Visual Flight Rules

VFXR(R) : Flap Retraction Speed

VFXR(X) : Flap Extension Speed

VG : Ground Velocity
VG : Validity Generalisation

VG/DG : Vertical Gyro/Directional Gyro

VGND : Ground Velocity
VGS : VHF Datalink Ground Station

VH : Maximum Level-flight Speed with Continuous Power  
VHF : Very High Frequency
VHF R/T : Very High Frequency Radio/Telephony
VHF-OTF : VHF Operations Task Force

VHRR : Very High-Resolution Radiometer

VHSIC : Very High Speed Interated Circuit
VI : Heading to Intercept (ARINC 424 Path Terminator)

VIA : By way of

VICE : Instead/Versus
VID : Visual Image Display

VIP : Very Important Person
Vis : Visual aids

VIS : Visibility

VISSR : Visible Infrared Spin Scan Radiometer

VL : Very Low ATC Complexity

Vls : Lowest Selectable Airspeed
VLBI : Very Long Baseline Interferometry
VLCT : Very Large Capacity Transport

VLE : Landing Gear Extended Placard Airspeed  
VLF : Very Low Frequency

VLO : Maximum Landing Gear of Operating Speed

VLOF : Lift-off Speed

VLR : Very Long Range
VLSI : Very Large Scale Integration
VLUT : Video Look-Up Table

VM : Regional Airlines France (airline)
VM : Heading to a Manual Termination (ARINC 424 Path Terminator)

VMAX : Basic Clean Aircraft Maximum CAS
VMC : Visual Meteorological Conditions

VMC : Minimum Control Speed with Critical Engine Out

VM(LO) : Minimum Maneuver Speed
VMMS : VHF Multi-frequency Management Unit 

VMIN : Basic Clean Aircraft Minimum CAS

VMO : Velocity Max Operating

VN : Valid Negatives

VNAV : Vertical Navigation (provides computer description of aircraft's speed and altitude that can be tracked by autoflight system)

VNE : Never-exceed Speed

VNO : Maximum Structural Cruising Speed 
VNSE : Vertical Navigation System Performance

VO : Tyrolean Airways (airline)
VOI : Volume of Operational Interest
VoL : Value of Life
VOL : Volume
VOLMET : Meteorological Information for Aircraft in Flight
VOLMET : Routine Weather Reports Broadcast on VHF

VOM : Volt-ohm-milliammeter

VOR : VHF OmniRange Navigatgion System (ground navigational aid that can provide display of aircraft position relative to course through selected ground navigational radio transmitter)

VOR/DME, VOR-DME : VHF Omni-directional Ranging / Distance Measurement Equipment
VOT : VHF Omnidirectional Range Test – VOR-reciever test facility

VOT : VOR airborne equipment test facility
VP : Vertical Profile
VPAE : Vertical Profile Angle Error

VPATH : Vertical Path
VPIP : Vertical Intercept Point
VP : Valid Positives
VPD : Vertical Polar Diagram

VR : Cabo Verde Airlines (airline)
VR : Heading to a VOR Radial (ARINC 424 Path Terminator)

VR : Takeoff Rotation Velocity

VRB : Variable (meteo)

VREF : Approach Reference speed
VRRS : Voice Recording and Display System
VRS : Voice Response System

VS : Stalling Speed
VS : Vocational Stabilisation

VS : Design Speed for Maximum Gust Intensity

VSA : By Visible reference to the ground
VSAT : Very Small Aperture satellite Terminal

VSBY : Visibility
VSCS : Voice Switching and Control System
VSD : Vision and Strategy Document

VSI : Stalling Speed in a Specified Flight Configuration

VSI/TRA : Vertical Speed Indicator/Traffic, Resolution Advisory
VSIG : Vertical Separation Implementation Group
VSM : Vertical Separation Minimum

VSO : Stalling Speed in the Landing Configuration
VSP : Variable System Parameter

VSP : Vertical Speed

VSSE : Intentional One Engine Inoperative Speed is a minimum speed selected by the manufacturer for intentionally rendering one engine inoperative in flight.
VSSG : Vertical Separation Sub-Group

VSTOL : Vertical or Short Takeoff and Landing
VSWR : Voltage Standing Wave Ratio

VTK : Vertical Track Distance
VTN : Voice Telecommunications Network
VTOL : Vertical Take-Off and Landing

V/TRK : Vertical Track

VTR : Variable Takeoff Rating
VTS : Vessel Traffic Services
VTT : Vertical Threshold Test

VU : Utility Speed
VVD : Vertical View Display
VWF : Video For Windows

VX : Speed for Best Angle of Climb

VY : Speed for Best Rate of Climb

Vl : Critical Engine Failure Velocity (Takeoff Decision Speed)

V2 : Takeoff Climb Velocity




w : Wake Vortex category
W : Watt

W : West

W : White

W2 : World Airlines (airline)

W/MOD : With Modification of Vertical Profile

W/STEP : With Step Change in Altitude
WAA : Wide Area Augmentation
WAC : World Aeronautical Chart
WAAS : Wide Area Augmentation System

WAC : World aeronautical chart-ICAO 1:1.000.000
WACS : Wireless Airport Communications Systems
WAD : Wide Area Differential
WAD-GNSS : Wide Area Differential GNSS
WADGPS : Wide Area Differential GPS
WAFC : World Area Forecast Centre
WAFS : World Area Forecast System
WAGE : Wide Area GPS Enhancement program
WAN : Wide Area Network
WARC : World Administrative Radio Communication Conference
WARC-MOB : World Administrative Radio Communication Conference - Mobile Communication.

Waypoint : Position in space usually on aircraft's flight plan

WB : Westbound

WBAR : Wing Bar Lights

WBC : Weight and Balance Computer

WBS : Weight and Balance System
WBS : Work Breakdown Structure
WC : Waypoint Capture
WCL : Weather Channel

WDI : Wind Directon Indicator

WDSPR : Widespread
WDW : Window
WEA : Whole ECAC Area
WEF : With Effect From or Effective From
WEU : Western European Union (military matters)
WG : Working Group

WGCS-84 : World Global Co-ordinate System 1984
WGPDS : Word and Graphics Process Documentation System
WGR : Working Group on Route Charges
WGRSG : Sub-Group of the Charges Working Group
WGS : World Geodetic System
WGS : World Geodetic Survey
WGS-72 :  : World Geodetic System/Standard (1972)
WGS-84 : World Global System 84, which is the ICAO recommended parameterisation of an ellipsoid earth model

WI : Within

WID : Width

WIE : With immediate effect or effective immediately

WILCO : Will Comply

WINDR : Wind Direction

WINDMG : Wind Magnitude

WINTEM : Forecast upper wind and temperature

WIP : Work in Progress
WIPO : World Intellectual Property Organisation
WIRS : Wide Area Reference Stations

WKDAYS : Monday through Friday

WKEND : Saturday and Sunday

WKN : Weaken or Weakening
WKSP : Transmission Centres Workshop ; Data Transmission Workshop
WLA : WorkLoad Assessment
WM : Working Memory
WMB : Window Management Button
WMO : World Meteorological Organisation

WMSC : Weather Message Switching Center

WMSCR : Weather Message Switching Center Replacement

WND : Wind

WNW : West-North-West

WO : Without

WO : World Airways
WOC : Wing Operations Centre
WOD : Word Of the Day
WORM : Write Once, Read Many
WP : Way-Point
WP : Work Package
WP : Work Programme
WP : Working Paper
WP : Working Position
WPD : Work Programme Document
WPL : Work Package Leaders 
WPM : Words Per Minute
WPn : First waypoint in the next sector
WPP : Working Position Processor

WPT : Way point
WRC : World Radio-communications Conferences
WPs : Working Positions
WPx : Next waypoint on the flight plan

WRNG : Warning
WS : Work Station
WS : Watch Supervisor

WS : Wind Shear
WSC : West Sector Co-ordinator

WSPD : Wind Speed

WSR : Wet Snow on Runway(s)

WSW : West-South-West

WT : Weight
WTC : Wake Turbulence Category

WTSPT : Waterspout

WTR : Water on Runway(s)

WTWS : Windshear and Turbulence Warning System
WWW : World Wide Web (INTERNET)
WX : Weather

WX DEF : Weather Deviation
WXMS : Weather Mapping System

WXR : Weather Radar




X : Cross

(X) : Irregular

X-BAND The frequency range between 8000 and 12500 MHz

X-Wind : Cross Wind

X25 : Standard protocol in telecommunications
X.25 : Packet Switched Data Network
XAP : Crossing Alternate Proposal Message
XASM : Cancel Assume
XASP : Extended AIRCOM Service Processor

XBAR : Crossbar (of approach lighting system)
XBRIGHT : Cancel highlighting
XCM : Crossing Request Cancelation Message 
XCONF : Delete CONFlict
XCOORD : Cancel Co-ordination
XCOP : Exit Co-ordination Point
XCOR : Cancel Correlation

XCVR : Transceiver
XECM : Cancel Executive Controller Message
XEU : European Currency Unit (ECU)
XEXPLT : Cancel Extrapolation
XFDM : Cancel FDM
XFL : Exit Flight Level (from a sector or volume of airspace)

XFR : Transfer
XFRQ : Cancel FreQuency message
XGEO : Cancel GEO
XHOLD : Cancel Hold
XIFL : Cancel Intermediate Flight Level
XIN : Crossing intentions
XIN : Military Crossing Intention Notification Message

XLTR : Translater

XM : External Master

XMIT : Transmit

XMITR : Transmitter

XNG : Crossing

XTRK : Cross Track Error

XPD : ATC Transponder (also XPDR, XPNDR, TPR)

XPDR : Transponder
XPNDR : Transponder
XMT : Excluding (Messager)
XOFF/PDR : Cancel Off Predetermined Route
XPLN : Cancel Plan
XPT : Exit Point of a sector (ODID)
XQDM : Cancel QDM
XRA : Crossing Request Answer (SEROS / MADAP)
XRQ : Airspace Crossing Request Message (Airspace Crossing Dialogue)

XS : Atmospherics
XSFL : Cancel Supplementary Flight Level
XSSRBRIGH : Cancel SSR highlight
XSTAT : Cancel Statistics
XTDCP : Cancel Test Display Control Panel
XTEDD : Cancel Test Electronic Data Display

XT : Air Exel (airline)
XTK : Cross Track Distance

XTK : Crosstrack (cross track error)
XTRK : Cancel Track
XTT : Across Track Tolerance

XX… : Heavy (used to qualify weather phenomena such as rain, e.g. heavy rain = XXRA)

XY : Ryan Air



Y : Yellow

YCZ : Yellow caution zone (runway lighting)

Yd : Yards

YD :Yaw Damper

YR : Your

YSAS : Yaw Stability Augmentation System

YU : The Federal Republic of Yugoslavia (ISO Country Code)



Z : Zulu (GMTtime)

ZA : South Africa (ISO Country Code)

ZFW : Zero Fuel Weight

ZNY : New York Air Route Traffic Control Center  
ZOC : Zone of Convergence
ZOE : Zone d'Echange

ZVF : Zero Velocity Filter




This site was last updated 07/23/08