AIP — Aeronautical Information Publication Role: A comprehensive manual with essential aeronautical data. Context: Contains charts, procedures, and regulatory details vital for flight planning.
AIRMET — Aeronautical Meteorological Information
airprox — An airprox is a situation in which, in the opinion of a pilot or air traffic services personnel, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft involved may have been compromised. (ICAO Doc 4444: PANS-ATM).
AIS — Aeronautical Information Service
ALT — Altitude
AltMoC — alternative means of compliance
ALTN — Alternate
AM — Amplitude Modulation
AMC — Acceptable Means of Compliance
AMC-20 — general Acceptable Means of Compliance for airworthiness of products, parts and appliances
AMD — Amended. Shows that the forecast has been updated from a previous version.
AME — aero-medical examiner
AMHS — Aeronautical Message Handling System
AML — aircraft maintenance licence
AMM — aircraft maintenance manual
AMO — approved maintenance organisation
AMOC — Alternative Method of Compliance
AMS — apron management services
AMSL — Above Mean Sea Level
AMTO — approved maintenance training organisation (Part-147)
ANAC — Agência Nacional de Aviação Civil (Brazilian national aviation authority)
Annex 11 — Air Traffic Services
Annex 14 — Aerodromes
Annex 6 — Operation of Aircraft
Annex 8 — Airworthiness of Aircraft
ANP — Actual Navigation Performance
ANS — air navigation services
ANSP — air navigation service provider
ANT — Antenna
AOA — Angle of Attack
AOC — Air Operator Certificate; Air Operator’s Certificate Role: Certification permitting an airline or commercial operator to conduct air transport operations. Context: Requires strict evaluation of operational procedures, maintenance, and training.
AOG — Aircraft on Ground Meaning: Indicates an aircraft is grounded due to technical issues, often causing delays.
AOR — Area of Responsibility
AP — Accelerated (rulemaking) procedure
APP — Approach
APR — Apron
APU — Auxiliary Power Unit
ARA — authority requirements (in the Aircrew Regulation)
ARAC — Aviation Rulemaking Advisory Committee
ARINC — Aeronautical Radio, Incorporated
ARPT — Airport
ART — Eurocontrol Agency Research Team
ARTE — Above Runway Threshold Elevation
ASAWG — ARAC Airplane-level Safety Analysis Working Group
ASBUs — Aviation System Block Upgrades
ASDA (Accelerate-Stop Distance Available) — Runway length plus stopway for aborted takeoffs.
ASHTAM — NOTAM related to volcanic ash contamination in the atmosphere.
ASISP — Aircraft Systems Information Security/Protection
ASR — annual safety review
AT — Occasionally used in TAFs to specify a particular time within the forecast period.
ATA — Actual Time of Arrival
ATC — Air Traffic Control
ATCO — air traffic controller
ATIS — Automatic Terminal Information Service
ATM — air traffic management
ATN — Aeronautical Telecommunication Network Role: A digital network interconnecting aircraft, ATC, and other stakeholders for efficient data exchange.
ATO — approved training organisation
ATPL — air transport pilot licence
ATS — Air Traffic Services
ATSEP — air traffic safety electronics personnel
ATT — Attitude
AUTO — Automatic
AUX — Auxiliary
AVAIL — Available
AVSEC — Aviation Security Role: Encompasses measures and protocols designed to protect aviation infrastructure, aircraft, and passengers from security threats.
AWOS — Automated Weather Observing System Role: An automated system that collects and broadcasts weather data, particularly at smaller or remote airports.
AWOs — all-weather operations
B) — Start time; Start of validity
B/C or BCRS — Back Course
B777 — Boeing 777
BARO — Barometric
BASA — Bilateral Aviation Safety Agreement
BAT / BATT — Battery
BEA — Bureau d'Enquêtes et d'Analyses (French Safety Investigation Authority)
BECMG — Becoming. Indicates that weather conditions are expected to change gradually from one state to another.
BIS — Best Intervention Strategy
BKN — Broken. 5–7 oktas, meaning the sky is mostly covered by clouds but not completely overcast.
BPL — balloon pilot licence
BR — Mist. Fine droplets suspended in the air that reduce visibility, but typically not as severely as fog.
C-Check, D-Check, etc. — Meaning: Scheduled maintenance checks (though not “abbreviations” in the strict sense, these terms are ubiquitous in MRO documentation).
C-UAS — Counter Unmanned Aircraft Systems
CA — competent authority
CAA — civil aviation authority
CABA — Certification Authorities for Bilateral Agreements & Certification Procedures
CAE — Continued Aviation Education
CAEP — Committee on Aviation Environmental Protection (ICAO)
CAEP/10 — tenth meeting of the committee on Aviation Environmental Protection
CAEP/11 — eleventh meeting of the committee on Aviation Environmental Protection
CAG — Collaborative Analysis Group
CALLSIGN — ATC callsign for communication; Radio callsign for ATC communications
CANCEL — Cancelled NOTAM or restriction; Cancellation of NOTAM or restriction
CAO — combined airworthiness organisation – Annex Vd to Commission Regulation (EU) 2019/1383
CAPP — certification authorities for propulsion
CAS — Calibrated Airspeed Meaning: Indicated airspeed corrected for instrument and positional errors.
CASA — Civil Aviation Safety Authority of Australia
CAT — Commercial Air Transport
CAT I, II, III — category I, II, III
CATA — certification authorities for transport airplane
CAVOK — Ceiling and visibility okay (good weather); Ceiling And Visibility OK. Indicates that: Visibility is at least 10 km, There are no significant clouds below 5,000 feet (or the highest minimum sector altitude), and No significant weather phenomena (such as rain, snow, or thunderstorms) are present.
CAW — continuing airworthiness
CB — cumulonimbus; Circuit Breaker
CBA — cost-benefit analysis
CBMAM — Cumulonimbus Mammatus. A specific type of cumulonimbus cloud with a mammatus base, often indicating severe turbulence.
CBTA — competency-based training and assessment
CDFA — Continuous Descent Final Approach
CDM — Collaborative Decision Making Role: A process that integrates all stakeholders (airlines, ATC, airports) to optimize decision-making in air traffic management.
CDR — Commander Role: The pilot in command responsible for overall flight decisions.
CDU — Control Display Unit
CE — Critical Element
CEA — cost-effectiveness analysis
CERT-EU — Computer Emergency Response Team
CFIT — controlled flight into terrain
CG — Center of Gravity
CHECKLIST — NOTAM that provides a reference of all active NOTAMs for a particular location.
CHKL — Checklist
CIR — candidate issue register
CLB — Climb
CLR — Clear. Similar to SKC, used especially in U.S. reports to denote no clouds below a certain altitude.
CNS — communication, navigation and surveillance; Communication, Navigation, and Surveillance Role: An umbrella term for the integrated systems that underpin modern air traffic management.
CO/CO2 — carbon monoxide/carbon dioxide
CofA — certificate of airworthiness
COMM — Communication
CON — Continuous
CONFIG — Configuration
COR — As noted above, signifies that the forecast or report has been corrected.; Corrected Report. Denotes that the current report is a correction to a previously issued report.
CORAL — Certification and ORganisation ApprovaL information hub programme
CORSIA — Carbon Offsetting and Reduction Scheme for International Aviation
CPDLC — Controller - Pilot Data Link Communications Role: A text-based messaging system that supplements voice communications between pilots and controllers, reducing radio congestion.
CPL — commercial pilot licence
CRD — comment-response document
CRM — crew resource management
CRZ — Cruise
CS(s) — certification specification(s)
CS-22 — Certification Specifications for sailplanes and powered sailplanes
CS-23 — Certification Specifications for normal, utility, aerobatic and commuter aeroplanes
CS-25 — Certification Specifications for large aeroplanes
CS-26 — Certification Specifications for additional airworthiness specifications for operations
CS-27 — Certification Specifications for small rotorcraft
CS-29 — Certification Specifications for large rotorcraft
CS-34 — Certification Specifications for aircraft engine emissions and fuel venting
CS-ACNS — Certification Specifications for Airborne Communication, Navigation and Surveillance
CS-APU — Certification Specifications for Auxiliary Power Units
CS-CCD — Certification Specifications for cabin crew data
CS-CO2 — Certification Specifications for Aeroplane CO2 Emissions
CS-E — Certification Specifications for Engines
CS-ETSO — Certification Specifications for European Technical Standard Orders
CS-FCD — Certification Specifications for Flight Crew Data
CS-LSA — Certification Specifications for Light Sport Aeroplanes
CS-MMEL — Certification Specifications for Master Minimum Equipment List
CS-SIMD — Certification Specifications for Simulator Data
CS-STAN — Certification Specifications for Standard Changes/Standard Repairs
CS-VLA — Certification Specifications for Very Light Aeroplanes
CS-VLR — Certification Specifications for Very Light Rotorcraft
CSV — Certification Support for Validation
CTA — Control Area
CTAF — Common Traffic Advisory Frequency Role: A frequency used at non-towered airports for pilots to communicate position and intentions.
CTC — Centralized Traffic Control Role: A ground-based system used in some airports and terminal airspaces for efficient traffic management.
CTIG — Common Training Initiative Group
CTL — Control
CTR — Control Zone
CVR — cockpit voice recorder
CVS — combined vision systems
CZ — Czech Republic
DA — Decision Altitude; (European Commission) delegated act
DAH — design approval holder: used only if all of the following items are included: holder of a type-certificate, a restricted type-certificate, a supplemental type-certificate, a European Technical Standard Order (ETSO) authorisation, a major repair design approval, a major change design approval or any other relevant approval or authorisation for the design of aeronautical products, parts and appliances deemed to have been issued under Commission Regulation (EU) No 748/2012.
DAT provider — (aeronautical) data provider, indirectly, competent authority
Data Link — Role: Digital communications (e.g., ACARS, CPDLC) that transmit operational and safety data between aircraft and ground systems.
DC — Direct Current
DD — Day of the month
DDA — Derived Decision Altitude
ddd — Wind direction in degrees true (e.g., 180 means wind from the south)
dddffKT — The wind group in METAR reports: ddd : Wind direction in degrees true (e.g., 180 means wind from the south) ff : Wind speed in knots KT : Knots Example: 18012KT = Wind from 180° at 12 knots.
dddVddd — Indicates variable wind direction when it fluctuates more than 60° during the observation. Example: 180V240 means the wind is varying between 180° and 240°.
DDG — Dispatch Deviations Guide
DDHHMMZ — The date-time group format where: DD : Day of the month HHMM : Time in hours and minutes Z : Zulu time (UTC) Example: 151230Z = 15th day of the month at 12:30 UTC.
DE-ICE — De-icing services
DEFIS — Defence Industry and Space
DEP ARR — Departure / Arrival
DES — Descent
DEU — Display Electronics Unit
DISC — Disconnect
DL — deep learning (Artificial Intelligence)
DLS — Data Link Services
DM — downlink message
DME — Distance Measuring Equipment
DOA — design organisation approval
DP — direct publication (rulemaking procedure)
DS — Duststorm. Similar to a sandstorm, but primarily involving dust.
DSPL — Display
DTO — declared training organisation
DU — Dust. Fine particles that can lower visibility, especially in arid regions.
DZ — Drizzle. Light liquid precipitation consisting of very small droplets.
E) — Reason for closure (temporary maintenance and LVP); Operational detail (Runway closed for work; landing/take-off prohibited)
E/D — End of Descent
E/E — Electrical and Electronic
EAB — EASA Advisory Bodies – Expert panels that advise EASA on technical, operational, and regulatory matters.
EACWG — Engine/Aircraft Certification Working Group
EAEG — ECAC European Aviation Environmental Group
EAER — European Aviation Environmental Report
EAFDM — European Authorities Coordination Group on Flight Data Monitoring
EAPPRE — European Action Plan for the Prevention of Runway Excursions
EAPPRI — European Action Plan for the Prevention of Runway Incursions
EASA — European Aviation Safety Agency; European Union Aviation Safety Agency
EASA MB — European Union Aviation Safety Agency Management Board; EASA Management Board – Governing body responsible for strategic decisions and oversight of EASA's operations and priorities.
EASP — European Aviation Safety Programme
EASp — European Aviation Safety Plan – The tactical component of the EASP. It identifies current safety issues and outlines targeted actions to mitigate risks within a defined time frame.
EATMN — European air traffic management network
EBAW — Enhanced Bank Angle Warning
EBT — Evidence-Based Training
EC — European Commission
ECAC — EASA European Civil Aviation Conference
ECAM (Electronic Centralized Aircraft Monitor) — Airbus’s system that provides system status, checklists, and procedural guidance.
ECCSA — European Centre for Cyber Security in Aviation
ECHA — European Chemicals Agency
ECQB — European Central Question Bank
ECR — European Central Repository for accident and incident reports in aviation
ECS — Environmental Control System
EDTO — extended diversion time operation
EEA — European Environment Agency
EEC — Electronic Engine Control
EFB — electronic flight bag
EFIS — Electronic Flight Instrument System
EFVS — enhanced flight vision systems
EGPWS — Enhanced Ground Proximity Warning System
EGT — Exhaust Gas Temperature
EHEST — European Helicopter Safety Team
EHPU — electric and hybrid propulsion unit
EHSIT — European Helicopter Safety Implementation Team
EI — Effective Implementation
EICAS (Engine Indication and Crew Alerting System) — Used in Boeing aircraft to monitor engine/system performance and alert crews to anomalies.
EICAS/ECAM — EICAS (Engine Indication and Crew Alerting System): Used in Boeing aircraft to monitor engine/system performance and alert crews to anomalies. ECAM (Electronic Centralized Aircraft Monitor): Airbus’s system that provides system status, checklists, and procedural guidance.
ELA — European light aircraft
ELA1 aircraft — ELA1 aircraft’ means the following manned European light aircraft: — an aeroplane with a maximum take-off mass (MTOM) of 1 200 kg or less that is not classified as a complex motor-powered aircraft; — a sailplane or powered sailplane of 1 200 kg MTOM or less; — a balloon with a maximum design lifting gas or hot air volume of not more than 3 400 m3 for hot air balloons, 1 050 m3 for gas balloons, and 300 m3 for tethered gas balloons.
ELEC — Electrical
ELEV — Elevator
ELT — Emergency Locator Transmitter Role: Automatically transmits a distress signal in the event of a crash to facilitate search and rescue.
eMCO — Extended Minimum-Crew Operations
EMS — emergency medical services
ENG — Engine
EOC — essential operational changes
EOFDM — European Operators Flight Data Monitoring forum
EOSID — Engine Out Standard Instrument Departure
EPAS — European Plan for Aviation Safety
EPR — Engine Pressure Ratio Purpose: A key performance metric comparing exhaust pressure to inlet air pressure.
ERCS — European Risk Classification Scheme
EREA — European Research Establishments in Aeronautics
ESCP — European Strategic Coordination Platform
ESPN-R — European Safety Promotion Network Rotorcraft
ETS — European Union Emissions Trading System (EU ETS) is the cornerstone of the European Union's policy to tackle climate change and its key tool for cost-effective reduction of emissions of carbon dioxide (CO ) and other greenhouse gases (GHG) in the power, 2 aviation and industrial sectors. The EU ETS works on the 'cap and trade' principle and is a market-based measure where participants are required to monitor and report their emissions and surrender sufficient emission allowances to cover their reported emissions in each year.
ETSO — European Technical Standard Order
ETSOA — European technical standard order (authorisation)
EU — European Union
EUROCAE — European Organisation for Civil Aviation Equipment
EVT — evaluation task
eVTOL — Electric Vertical Take-Off and Landing Role: Refers to a new class of electric-powered aircraft designed for urban air mobility with vertical lift capabilities.
EWIS — Electrical Wiring Interconnection System
EXEC — Execute
EXER — Exercise (e.g., military or civil aviation exercises); Exercise (e.g., military or special operational exercises)
EXT — Extend
F — Fahrenheit
F) — Additional operational note (ILS CAT II operation for a different runway)
F/D or FLT DIR — Flight Director
F/O — First Officer
FA — Flight Attendant
FAA — Federal Aviation Administration
FAA AIM — Aeronautical Information Manual
FADEC — Full Authority Digital Engine Control Purpose: Fully manages engine performance, optimizing fuel efficiency and responsiveness while reducing pilot workload.
FAF — Final Approach Fix
FANS — Future Air Navigation System Role: An evolving suite of technologies enhancing communication, navigation, and surveillance (especially over oceanic airspace).
FAP — Final Approach Point
FAR — Federal Aviation Regulations Role: The set of rules established by the FAA governing all U.S. civil aviation activities.
FAR 33.90 — Federal Aviation Regulation Section 33.90 — Initial maintenance inspection test
FAS — Final Approach Segment
FBO — Fixed Base Operator Role: A ground service provider at an airport offering fueling, hangaring, maintenance, and handling services.
FbW/FBW — fly-by-wire
FC — flight crew; Funnel Cloud. A rotating column of air that has not reached the ground, sometimes a precursor to a tornado.
FCC — Flight Control Computer
FCD — flight crew data
FCHWG — ARAC Flight Controls Harmonization Working Group
FCL — flight crew licensing
FCOM — flight crew operating manual
FCTL — Flight Control
FCTM — Flight Crew Training Manual
FDM — flight data monitoring
FDR — flight data recorder
FEM — flight examiner manual
FEW — Few. 1–2 oktas (eighths) of the sky covered by clouds.
ff — Wind speed in knots
FFM — Force Fight Monitor
FG — Fog. A thick cloud of water droplets at ground level causing significantly reduced visibility.
FIR — Flight Information Region
FIR (LIR) — Lower Information Region
FIR (UIR) — Upper Information Region
FIS — Flight Information Service
FL — Flight Level
FM — From. Marks the beginning of a period during which forecast conditions are expected to change. Example: FM1200 indicates that from 12:00 UTC onward, new conditions will prevail.
FMA — Flight Mode Annunciation; Flight Mode Annunciator Role: Indicates active autopilot modes and flight director commands.; Flight Mode Annunciator Role: Displays the active autopilot modes and flight director commands to the pilot.
FMC — Flight Management Computer
FMS — Flight Management System
FMS/FMC — Flight Management System/Computer Role: An onboard system that automates flight planning, navigation, and performance management.
FO — First Officer Role: The co-pilot assisting the commander and capable of assuming command if needed.
FoC — Focused Consultation
FOD — foreign object debris
FOQA — Flight Operational Quality Assurance Role: Collects and analyzes flight data to identify trends, improve procedures, and prevent future incidents.
FPA — Flight Path Angle
FPL — Flight Plan
FPV — Flight Path Vector
FR — France
FRM — fatigue risk management
FS — flight standards
FSB — Flight Standardisation Board (FAA)
FSEU — Flap Slat Electronic Unit
FSTD — Flight Simulation Training Device
FTL — flight time limitation
FTS — flight time specifications
FU — Smoke. Usually from fires or industrial activity; can reduce visibility.
FUEL — Fuel availability (e.g., Jet A1, Avgas)
FW — fixed wing
FZ — Freezing (e.g., freezing rain, freezing fog)
G — Gust. Indicates short bursts of higher wind speed. For instance, “G25” means gusts up to 25 knots.
G/P — Glide Path
G/S — Glide Slope
GA — Go-Around; General Aviation: It means any civil aircraft operation other than aerial work or commercial air transport (Commission Implementing Regulation (EU) 2017/373)
GA.COM — General Aviation Committee (EASA Advisory Body)
GAMET — General Aviation Meteorological Information
GR — Hail. Spherical ice pellets that form in strong convective storms.
GS — Small Hail or Snow Pellets. Generally smaller than typical hail.; Ground Speed Meaning: The speed of the aircraft relative to the ground, considering wind effects.
GSE — ground support equipment
H2020 — Horizon 2020
HA — higher airspace (above FL 600/650)
HAZ — Hazardous
HAZARDOUS — Hazardous conditions (e.g., volcanic ash, chemical spills)
HDG — Heading
HDG REF — Heading Reference
HDG SEL — Heading Select
HE — helicopter manufacturers, operators, training organisations, maintenance organisations
HEMS — helicopter emergency medical services
HF — human factors; High Frequency
HF (High Frequency) — For long-range communications over oceans or remote areas.
HF CAG — Human Factors Collaborative Analysis Group
HF, VHF, & UHF Radios — HF (High Frequency): For long-range communications over oceans or remote areas. VHF (Very High Frequency): The primary band for civil aviation voice communications and some navigation signals. UHF (Ultra High Frequency): Commonly used by military aviation and specific ground communications.
HHMM — Time in hours and minutes
HOSSWG — Helicopter Offshore Safety and Survival Working Group (JAA)
HP — human performance
HPA — Hectopascals; high-performance aircraft
HTAWS — helicopter terrain awareness warning systems
HUD — Head-Up Display
HYD — Hydraulic
HZ — Haze. A slight obscuration of the sky caused by dust, smoke, or pollution.
IA — (Commission) implementing act
IAF — initial approach fix
IAN — Integrated Approach Navigation
IAP — Instrument Approach Procedure
IAS — Indicated Airspeed
IATA — International Air Transport Association Role: A global trade association representing airlines. Context: Develops standards for ticketing, baggage handling, and operational procedures, and influences airline policies.
IAW — In Accordance With; initial airworthiness
IC — Ice Crystals. Tiny ice particles falling from the sky.
ICA — instructions for Continued Airworthiness
ICAO — International Civil Aviation Organization
ICAO Doc 8400 — Abbreviations and Codes
ICAO SL — ICAO State letter
ICING — Icing conditions
IDENT — Identification
IFE — in-flight entertainment
IFP — instrument flight procedures
IFR — Instrument Flight Rules
IFTSS — individual flight time specification scheme
IHST — International Helicopter Safety Team
ILS — Instrument Landing System
ILS CAT I, II, III — Instrument Landing System, Category I, II, III
IMC — Instrument Meteorological Conditions
IMF — International Monetary Fund
IMI — initial maintenance inspection
IMMR — Integrated Multi-Mode Receiver
IN — Inches
INACT — Inactive (services, navaids, or equipment)
INBD — Inboard
IND LTS — Indicator Lights
INF — information management (in reflection to ATM Master Plan Level 3)
INJURY — Injuries reported (e.g., on ground or during operations)
INOP — Inoperative
INTC CRS — Intercept Course
IPC — Innovation Partnership Contract
IR — instrument rating
IRS — Inertial Reference System Role: Uses gyroscopes and accelerometers to determine the aircraft’s position, orientation, and velocity independently of external aids.
IS — Information Security
ISA — International Standard Atmosphere Purpose: A reference model of atmospheric pressure and temperature used for performance and design.
ISFD — Integrated Standby Flight Display
ISLN — Isolation
ITY — interoperability (in reflection to ATM Master Plan Level 3)
JAA — Joint Aviation Authorities
JATR — Joint Authorities Technical Review
K — Knots
KGS — Kilograms
KNKT — Komite Nasional Keselamatan Transportasi – National Transportation Safety Committee of Indonesia
KPI — key performance indicator
KRE — key risk element
KT — Knots Example: 18012KT = Wind from 180° at 12 knots.
L — Left
LAFI — light aircraft flight instructor
LAPL — light aircraft pilot licence
LAT — Latitude
LAT & LONG — Latitude and Longitude Geographical coordinates used in flight planning, navigation, and FMS route entry.
LBS — Pounds
LDA — Localizer-type Directional Aid
LDA (Landing Distance Available) — The runway length available for landing.
LDG ALT — Landing Altitude
LE — Leading Edge
LIM — Limit
LNAV — Lateral Navigation
LO — learning objective
LOC-I — loss of control – in-flight
LOCART — loss of control avoidance and recovery training
LOI — level of involvement
LOM — Locator Outer Marker
LONG — Longitude
LOSA — Line Operations Safety Audit Observational safety program capturing routine flight operations to proactively identify threats and errors.
LPR — language proficiency requirements
LPV — Localizer Performance with Vertical Guidance
LTO — Landing and Take-off Operations
LVL CHG — Level Change
LVO — low-visibility operation
LVP — Low Visibility Procedures
M Prefix — When “M” precedes a number (e.g., M05), it indicates a negative value (below zero).
M&S — modeling and simulation
MA — medical assessor
MAB — Member States Advisory Body
MAC — mid-air collision
MAG — Magnetic
MAN — Manual
MB — Management Board
MBT — multimedia based training
MCA — multi-criteria analysis
MCDU — Multipurpose Control and Display Unit Role: The pilot interface for the FMS, used to enter flight plans and adjust performance data.
MCF — maintenance check flight
MCP — Mode Control Panel
MDA — Minimum Descent Altitude
MEA — Minimum Enroute Altitude Role: The lowest altitude ensuring obstacle clearance and navigational aid signal coverage along a route.
MEL — Minimum Equipment List
MET — meteorology/meteorologic
MET provider — meteorological services provider, indirectly, competent authority
METAR — Meteorological Aerodrome Report
Meters (e.g., 9999) — In many parts of the world, visibility is reported in meters. A value like “9999” typically means visibility is 10 km or more.
MFD — Multifunction Display; Combines navigation, weather, and traffic information on one screen.
MFD & PFD — Multi-Function Display & Primary Flight Display MFD: Combines navigation, weather, and traffic information on one screen. PFD: Displays core flight data (attitude, airspeed, altitude, heading) as the primary reference.
MGB — main gearbox
MH17 — Malaysia Airlines flight 17
MIN — Minimum
MKR — Marker
ML — Machine Learning (artificial intelligence)
MLS — Microwave Landing System Role: An alternative precision approach system using microwave frequencies for guidance.
MLW (Maximum Landing Weight) — The highest weight at which an aircraft is allowed to land.
MMEL — master minimum equipment list
MMO — Maximum Mach Operating Speed
MO — maintenance organisation
MOC — Means of Compliance
MoC — Memorandum of Cooperation
MOD — Modify
MOPSC — maximum operational passenger seating configuration
MPL — multi-crew pilot licence
MRB — Maintenance Review Board
MRO — Maintenance, Repair, and Overhaul Role: Refers to the scheduled and unscheduled activities ensuring an aircraft remains airworthy.
MST — Member States’ task
MTO — maintenance training organisation
MTOM — maximum take-off mass
MTOW & MLW — MTOW (Maximum Takeoff Weight): The highest weight at which an aircraft can safely take off. MLW (Maximum Landing Weight): The highest weight at which an aircraft is allowed to land.
MTOW (Maximum Takeoff Weight) — The highest weight at which an aircraft can safely take off.
MTRS — Meters
MVA — Minimum Vectoring Altitude
MX — Maintenance
N1 — Low Pressure Rotor Speed; The rotational speed of the engine’s fan or low-pressure compressor.
N1 & N2 — Engine Speed Parameters N1: The rotational speed of the engine’s fan or low-pressure compressor. N2: The rotational speed of the high-pressure compressor. Context: Critical for monitoring engine performance and health.
N2 — High Pressure Rotor Speed; The rotational speed of the high-pressure compressor. Context: Critical for monitoring engine performance and health.
NAA — national aviation authority
NAV — Navigation (in reflection to ATM Master Plan Level 3)
NAV RAD — Navigation Radio
NCC — non-commercial air operations with complex motor-powered aircraft*
NCO — non-commercial air operations with other-than complex motor-powered aircraft* * The term ‘complex motor-powered aircraft’ is no longer defined in Regulation (EU) 2018/1139. Article 140(2) of that Regulation provides that no later than 12 September 2023, implementing rules adopted under Regulations (EC) Nos 216/2008 and 552/2004 shall be adapted to the new Basic Regulation. Until then, deleted or altered definitions will continue to apply.
ND — Navigation Display
NDB — Non-Directional Beacon
NextGen — next generation
NGAP — Next Generation of Aviation Professionals programme (ICAO)
NGO — non-governmental organisation
NGS — Nitrogen Generation System
NIL — Used when there is nothing noteworthy to report beyond standard conditions.
NM — Nautical Miles
NN — Neural Networks (artificial intelligence)
NO — Norway
NoAs — Network of Analysts
NOAT — No Air Traffic (area or sector)
NORAH — Noise Related Annoyance, Cognition, and Health
NORM — Normal
NOSIG — No Significant Change. Typically found in TAFs, meaning that no significant weather changes are expected during the forecast period.
NOTAM — Notice to Airmen (general term)
NPA — notice of proposed amendment
NPS — Navigation Performance Scales
NSA — national supervisory authority
NSC — No Significant Cloud. Indicates there are no significant clouds below 5000 feet and no CB or TCU observed.
NSW — No Significant Weather. Indicates that no notable weather phenomena are expected during the period in question.
NTSB — National Transportation Safety Board
nvPM — non-volatile particulate matter
OAT — Outside Air Temperature Purpose: The ambient air temperature outside the aircraft, used in performance calculations.
OBST — Obstacle (e.g., building or terrain)
ODP — Obstacle Departure Procedure Role: Preplanned routes that ensure obstacle clearance during departure.
OEM — original equipment manufacturer
OEW & ZFW — OEW (Operating Empty Weight): The weight of the aircraft with all operational items but without payload or usable fuel. ZFW (Zero Fuel Weight): The weight of the aircraft excluding usable fuel, critical for balance calculations.
OEW (Operating Empty Weight) — The weight of the aircraft with all operational items but without payload or usable fuel.
OFP — Operational Flight Plan Role: An enriched flight plan used by airlines containing additional performance data, fuel calculations, and alternate routing.
OHMPs — occupational health medical practitioners
OHU — Overhead Unit
OJ — Official Journal of the European Union
OPR — Operator (e.g., airline operator)
OPS — air operations
OpSpecs — operations specifications
OPT — Onboard Performance Tool
ORO — Organisation Requirements for Air Operations
ORO.FC — organisation requirements for air operations — flight crew
OSD — operational suitability data
OVC — Overcast. 8 oktas, indicating full cloud cover.
OVHD — Overhead
OVRD — Override
PANS — Procedures for Air Navigation Services
PAPI — Precision Approach Path Indicator
PARK — Aircraft parking area
Part 21 — Annex I to Regulation to Regulation (EU) 748/2012 - airworthiness and environmental certification of aircraft and related products, parts and appliances, as well as for the certification of design and production organisations
Part 21 Subpart H — Annex I to Regulation to Regulation (EU) 748/2012 – Subpart H - airworthiness certificates and restricted certificates of airworthiness
Part-145 — Annex II to Commission Regulation (EU) No 1321/2014 - maintenance organisation approvals
Part-147 — Annex IV to Commission Regulation (EU) No 1321/2014 - training organisations requirements
Part-26 — Annex I to Regulation (EU) 2015/640 - additional airworthiness requirements for operations
Part-66 — Annex III to Commission Regulation (EU) No 1321/2014 - certifying staff
Part-ARO — Annex II to Regulation (EU) 965/2012 - authority requirements for air operations
Part-FCL — Annex I to Regulation (EU) 1178/2011 - flight crew licensing
Part-M — Annex I to Commission Regulation (EU) No 1321/2014 - continuing airworthiness requirements
Part-MED — Annex IV to Regulation (EU) 1178/2011 - medical certification of pilots, medical fitness of cabin crew, certification of AMEs and requirements of GMPs and OHMPs
Part-MET — Annex V to Regulation (EU) 2017 373 - specific requirements for providers of meteorological services
Part-NCC — Annex VI to Regulation (EU) 965/2012
Part-NCO — Annex VII to Regulation (EU) 965/2012
Part-ORA — Annex III to Regulation (EU) 1178/2011 - organisation requirements for aircrew
Part-ORO — Annex III to Regulation (EU) 965/2012 - organisation requirements for air operations
Part-SPO — Annex VIII to Regulation (EU) 965/2012
PASS — Passenger
PBAOM — performance based aerodrome operating minima
PBN — Performance Based Navigation; Performance-Based Navigation
PBR — performance-based regulation
PCP — pilot common project (SESAR)
PCU — Power Control Unit
PDRA — predefined risk assessment
PED — personal electronic device
PERF INIT — Performance Initialization
PF — Pilot Flying
PFC — Primary Flight Computers
PFD — Displays core flight data (attitude, airspeed, altitude, heading) as the primary reference.
PIB — Pre-flight Information Bulletin, a compilation of current NOTAMs for a specific route or aerodrome.
PIC — Pilot In Command
PIREP — pilot report
PIS — public interest sites
PL — Ice Pellets (Sleet). Formed when rain partially freezes before reaching the ground.
PM — Pilot Monitoring; particulate matter
PNL — Panel
PO — Dust/Sand Whirls. Small swirling eddies of dust or sand often seen in windy conditions.
POA — production organisation approval
PoC — proof of concept
POS — Position
POS INIT — Position Initialization
PPL — private pilot licence
PRI — Primary
PRM — passengers with reduced mobility
PROB30 / PROB40 — Indicates a 30% or 40% probability that a certain weather phenomenon will occur during the forecast period.
PRW — Perspective Runway
PTU — Power Transfer Unit
PWS — Predictive Windshear System
Q — quarter; Indicates the altimeter setting in hectopascals (hPa). Example: Q1013 means an altimeter setting of 1013 hPa.
Q) — ICAO location and NOTAM subject/type (RWY closure); Query Prefix and area-specific restriction (London Heathrow, in this case)
QAR — Quick Access Recorder Purpose: Records flight data for rapid analysis and troubleshooting.
QFE — Aerodrome pressure setting; Altimeter setting reflecting the actual air pressure at the airfield (height above ground level).
QMS — quality management system
QNE — Standard pressure setting (1013.25 hPa)
QNH — Aerodrome altimeter setting; Sea-level pressure setting for altimeter; Altimeter setting adjusted to mean sea level (MSL).
QNH & QFE — QNH: Altimeter setting adjusted to mean sea level (MSL). QFE: Altimeter setting reflecting the actual air pressure at the airfield (height above ground level).
QRH — Quick Reference Handbook Role: Provides pilots with immediate, step-by-step procedures for abnormal or emergency situations.
R — Right
R&D — research and development
R.COM — Rotorcraft Committee (Advisory Body)
RA — Radio Altitude / Resolution Advisory; Rain. Precipitation in the form of water droplets.; Resolution Advisory Role: Immediate instructions from TCAS to climb or descend to avoid a collision.
RAAS — Runway Awareness and Advisory System
RAIM — Receiver Autonomous Integrity Monitoring A GPS integrity check algorithm to alert the crew if satellite data is unreliable.
RAMP — Ramp area; aerodrome ramp; Ramp and apron (areas designated for aircraft parking and service)
RASG — Regional Aviation Safety Group
RASP — Regional Aviation Safety Plan
RAT — Route Availability Warning
RCL — Reduced Capacity Limitations
RCP — Required Communication Performance
RE — runway excursion
REACH — Registration, Evaluation, Authorisation and Restriction of Chemicals — Regulation (EC) No 1907/2006
RECIRC — Recirculation
ReCo — reduced-crew operations
REF — Reference
RES — research actions
RESCUE — Rescue operations (e.g., aircraft or ship rescue missions)
RET — Retract
RF — Refill
RFFS — rescue and firefighting services
RFID — radio frequency identification device
RH — Right Hand
RI — runway incursion
RIA — regulatory impact assessment
RMK — Remarks. A section at the end of the report where additional, non-standard information is provided.
STAR — Standard Terminal Arrival Route (USA), Standard Instrument Arrival (ICAO); Standard Terminal Arrival Route Role: Preplanned arrival paths to streamline descent and integration into terminal airspace.
STAT — Status
STC — supplemental type certificate
STD — Standard; synthetic training device
STS — Speed Trim System
SUA — Special Use Airspace
sUAS — Small Unmanned Aircraft System Role: Refers specifically to smaller drones (often under 55 pounds) that operate under a more lenient regulatory framework.
SUSP — Suspended (e.g., temporary suspension of services)
SVGS — synthetic vision guidance system
SVS — synthetic vision system
SWIM — system wide information management
SYS inspections — Standardisation Domain ‘Systemic Enablers for Safety Management’. Standardisation inspections in this domain focus on the implementation of Regulation (EU) No 376/2014 on occurrence reporting and the verification of the CA management system.
T / TK / TRK — Track
T / TRU — True
T/D — Top of Descent
T/D Format (e.g., 15/08) — The first number represents the temperature in degrees Celsius, and the second number represents the dew point in degrees Celsius.
TA — Traffic Advisory
TACAN — Tactical Air Navigation Role: A military system providing bearing and distance data. Context: Often combined with VOR to form VORTAC.
TACDWG — Transport Aircraft Crashworthiness and Ditching Working Group
TAF — Terminal Aerodrome Forecast
TAG — Thematic Advisory Group
TAI — Thermal anti-ice
TAKE-OFF — Take-off runway operation (may be specified as a restriction)
TAS — True Airspeed Meaning: The actual speed through the air, adjusted for altitude and temperature.
TAT — Total Air Temperature
TAWS — Terrain Awareness and Warning System Role: An advanced version of GPWS that uses digital terrain databases for more precise alerts.
TBD — to be determined
TBO — time between overhaul
TC — type certificate
TCAS — traffic collision avoidance system; Traffic Alert and Collision Avoidance System
TCCA — Transport Canada Civil Aviation
TCO — Third Country Operator; third-country operator
TCU — Towering Cumulus. Cumulus clouds with significant vertical development that may signal unstable atmospheric conditions.
TDZE — Touch Down Zone Elevation
TE — Trailing Edge
TeB — Member State technical body
TeC — Stakeholder technical body
TEM — threat and error management
TEMP — Temporary (e.g., temporary restriction or closure)
TEMPO — , PROB30 / PROB40 , and NOSIG May appear within the TREND section to describe expected short-term variations.; Temporary. Signals that there will be temporary fluctuations or brief periods of differing weather conditions.
TFC — Traffic
TFR — Temporary Flight Restriction
THR HLD — Throttle Hold
TL — Until. Used to denote the end time for a particular forecast period or change in conditions.
TMA — Terminal Area; Terminal Control Area; terminal maneuvering area
TMG — touring motor glider
TO — Takeoff; training organisation
TO/GA — Takeoff / Go-Around
TODA (Takeoff Distance Available) — Runway length plus clearway.
TODA, ASDA, & LDA — TODA (Takeoff Distance Available): Runway length plus clearway. ASDA (Accelerate-Stop Distance Available): Runway length plus stopway for aborted takeoffs. LDA (Landing Distance Available): The runway length available for landing.
ToR — terms of reference
TRA — Temporary Restricted Area
TREND — Indicates short-term forecast appended to a SPECI report.
TRIGGER NOTAM — Short-term NOTAM alerting operators to changes in AIP or procedures.
TS — Thunderstorm. Used when thunderstorm activity is present. E.g., TSRA = thunderstorm with rain.
TSA — Temporary Security Area
TSO — technical standard order
TURB — Turbulence
TWR — Tower
TWY — Taxiway
UA — unmanned aircraft
UAS — unmanned aircraft system
UHF (Ultra High Frequency) — Commonly used by military aviation and specific ground communications.
UK — United Kingdom
ULD — unit load device
UP — Unknown Precipitation. Used when the type of precipitation cannot be determined.
UTP — Unscheduled Technical Problem Used in operational dispatch and maintenance logs to identify non-routine issues affecting aircraft readiness.
V/S — Vertical Speed
V1 — Takeoff Decision Speed
V2 — Takeoff Safety Speed
VA — Design Maneuvering Speed; Volcanic Ash. Fine volcanic particles suspended in the atmosphere, dangerous for aircraft.; Maneuvering Speed Meaning: The speed at which full, abrupt control inputs will not overstress the aircraft.
VASI — Visual Approach Slope Indicator Role: Similar to PAPI; uses calibrated light bars to help pilots maintain the correct approach angle.
VC — In the vicinity. Indicates that the weather phenomenon is occurring near (but not at) the reporting station.
VDF — Voice Data Follower (less common) Role: A system or protocol in certain contexts to automatically follow or log voice communications.
VFE — Maximum Flap Extended Speed Purpose: The highest speed at which flaps can be deployed safely.
VFR — Visual Flight Rules
VHF — Very High Frequency
VHF (Very High Frequency) — The primary band for civil aviation voice communications and some navigation signals.
VHM — vibration health monitoring
VLD — very large-scale demonstration
VLOS — visual line of sight
VMC — Visual Meteorological Conditions
VMO — Maximum Operating Speed
VNAV — Vertical Navigation
VNE — Never Exceed Speed Meaning: The maximum speed beyond which the aircraft must not operate to avoid structural damage.
VOR — VHF Omnidirectional Range; VHF Omni-directional Range Role: A ground-based radio navigation aid that provides azimuth information. Example: Helps pilots maintain a course along established airways.
VORTAC — VOR/TACAN Combination Role: Offers both azimuth and distance information from a single facility.
VR — Rotation Speed; virtual reality
VRB — Variable. Used when the wind direction is not steady (typically when speeds are very low, below 3 knots).
VREF — Reference Speed
VSD — Vertical Situation Display
VTK — Vertical Track
VTOL — vertical take-off and landing aircraft
VV — Vertical Visibility. Used when the sky is obscured (e.g., by fog or heavy precipitation) and only vertical distance can be measured.
WAAS — Wide Area Augmentation System Role: A specific SBAS that improves GPS accuracy for precision approaches such as LPV.
WFD — widespread fatigue damage
WG — working group
WIDDCWG — Water Impact, Ditching Design and Crashworthiness Working Group (JAA)
WP — working paper/working package
WPGR — Report of the Wise Person Group on the future of the Single European Sky, April 2019
WPT — Waypoint
WS — Wind Shear
WXR — Weather Radar; Weather-related NOTAM
XTK — Cross Track
Z — Zulu time (UTC) Example: 151230Z = 15th day of the month at 12:30 UTC.; Short for Zulu time, which is equivalent to Coordinated Universal Time (UTC).
ZFW (Zero Fuel Weight) — The weight of the aircraft excluding usable fuel, critical for balance calculations.
ALS — Approach Lighting System
ALSF — Approach Lighting System with Sequenced Flashing Lights
ALSF-1 — Approach Lighting System with Sequenced Flashing Lights, Configuration 1
ALSF-2 — Approach Lighting System with Sequenced Flashing Lights, Configuration 2
BALS — Basic Approach Lighting System
CALVERT — Calvert Approach Lighting System
HIALS — High Intensity Approach Lighting System
HIRL — High Intensity Runway Lights
MALS — Medium Intensity Approach Lighting System
MALSR — Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights
MALSF — Medium Intensity Approach Lighting System with Sequenced Flashing Lights
MIRL — Medium Intensity Runway Lights
ODALS — Omni-Directional Approach Lighting System
PALS — Precision Approach Lighting System
RAIL — Runway Alignment Indicator Lights
REIL — Runway End Identifier Lights
RCL — Runway Centerline Lights
RCLS — Runway Centerline Lighting System
RCLL — Runway Centerline Lights
SALS — Short Approach Lighting System
SALSF — Short Approach Lighting System with Sequenced Flashing Lights
SSALR — Simplified Short Approach Lighting System with Runway Alignment Indicator Lights
SSALS — Simplified Short Approach Lighting System
SSALSF — Simplified Short Approach Lighting System with Sequenced Flashing Lights