Abbreviations marked yellow in HTML (printed in italics in PDF) are either different from or not contained in ICAO Doc 8400.
| A - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| A | amber |
| A* | FRA arrival connecting point |
| AA* | approved agency |
| AAA | (or AAB, AAC... etc., in sequence) amended meteorological message (message type designator) |
| A/A | air-to-air |
| AAD | assigned altitude deviation |
| AAIM | aircraft autonomous integrity monitoring |
| AAL | above aerodrome level |
| AAR | air to air refuelling |
| ABI | advance boundary information |
| ABM | abeam |
| ABN | aerodrome beacon |
| ABT | about |
| ABV | above |
| AC | altocumulus |
| ACARS | aircraft communication addressing and reporting system (to be pronounced "AY-CARS") |
| ACAS | airborne collision avoidance system (to be pronounced "AY-CAS") |
| ACC | area control centre or area control |
| ACCID | notification of an aircraft accident |
| ACFT | aircraft |
| ACK | acknowledge |
| ACL | altimeter check location |
| ACL* | ATC clearances and instructions |
| ACM* | ATC communications management |
| ACN | aircraft classification number |
| ACP | acceptance (message type designator) |
| ACPT | accept or accepted |
| ACT | active or activated or activity |
| AD | aerodrome |
| ADA | advisory area |
| ADC | aerodrome chart |
| ADDN | addition or additional |
| ADF | automatic direction finding equipment |
| ADIZ | air defence identification zone (to be pronounced "AY-DIZ") |
| ADJ | adjacent |
| ADO | aerodrome office (specify service) |
| ADR | advisory route |
| ADS | the address (when this abbreviation is used to request a repetition, the question mark (IMI) precedes the abbreviation, e.g. IMI ADS) (to be used in AFS as a procedure signal) |
| ADS-B | automatic dependent surveillance - broadcast |
| ADS-C | automatic dependent surveillance - contract |
| ADSU | automatic dependent surveillance unit |
| ADVS | advisory service |
| ADZ | advise |
| AES | aircraft earth station |
| AFIL | flight plan filed in the air |
| AFIS | aerodrome flight information service |
| AFISO* | AFIS operator |
| AFIZ* | aerodrome flight information zone |
| AFM | yes or affirm or affirmative or that is correct |
| AFS | aeronautical fixed service |
| AFT | after... (followed by time or place) |
| AFTN | aeronautical fixed telecommunication network |
| A/G | air-to-ground |
| AGA | aerodromes, air routes and ground aids |
| AGL | above ground level |
| AGN | again |
| AIC | aeronautical information circular |
| AIDC | air traffic services interfacility data communication |
| AIM | aeronautical information management |
| AIP | aeronautical information publication |
| AIRAC | aeronautical information regulation and control |
| AIREP | air report |
| AIRMET | information concerning en-route weather phenomena which may affect the safety of low-level aircraft operations |
| AIS | aeronautical information services |
| ALA | alighting area |
| ALERFA | alert phase |
| ALR | alerting (message type designator) |
| ALRS | alerting service |
| ALS | approach lighting system |
| ALT | altitude |
| ALTN | alternate or alternating (light alternates in colour) |
| ALTN | alternate aerodrome |
| AMA | area minimum altitude |
| AMC* | airspace management cell |
| AMC* | ATC microphone check |
| AMD | amend or amended (used to indicate amended meteorological message; message type designator) |
| AMDT | amendment (AIP amendment) |
| AMHS* | ATS message handling system |
| AMS | aeronautical mobile service |
| AMSL | above mean sea level |
| AMSS | aeronautical mobile satellite service |
| ANC | aeronautical chart - 1:500 000 (followed by name/title) |
| ANCS | aeronautical navigation chart - small scale (followed by name/title and scale) |
| ANM* | ATFM notification message |
| ANS | answer |
| AO | aircraft operator |
| AOC | aerodrome obstacle chart (followed by type and name/title) |
| AOCS* | air operations control station |
| AOM* | airside operations manager |
| AP | airport |
| APAPI | abbreviated precision approach path indicator (to be pronounced "AY-PAPI") |
| APCH | approach |
| APDC | aircraft parking/docking chart (followed by name/title) |
| APN | apron |
| APP | approach control office or approach control or approach control service |
| APR | April |
| APRX | approximate or approximately |
| APSG | after passing |
| APU | auxiliary power unit |
| APV | approach procedure with vertical guidance |
| ARC | area chart |
| ARINC* | navigation system database specification (Aeronautical Radio Incorporated) |
| ARNG | arrange |
| ARO | air traffic services reporting office |
| ARP | aerodrome reference point |
| ARP | air-report (message type designator) |
| ARQ | automatic error correction |
| ARR | arrival (message type designator) |
| ARR | arrive or arrival |
| ARS | special air-report (message type designator) |
| ARST | arresting (specify (part of) aircraft arresting equipment) |
| AS | altostratus |
| ASAP | as soon as possible |
| ASC | ascent to or ascending to |
| ASDA | accelerate stop distance available |
| ASE | altimetry system error |
| ASHTAM | special series NOTAM notifying, by means of a specific format, change in activity of a volcano, a volcanic eruption and/or volcanic ash cloud that is of significance to aircraft operations |
| ASM* | airspace management |
| ASPH | asphalt |
| ASR* | altimeter setting region |
| AT | at (followed by time at which weather change is forecast to occur) |
| ATA | actual time of arrival |
| ATAS* | automatic telephone answering system |
| ATC | air traffic control (in general) |
| ATCSMAC | air traffic control surveillance minimum altitude chart (followed by name/title) |
| ATD | actual time of departure |
| ATFM | air traffic flow management |
| ATIS | automatic terminal information service (to be pronounced "AY-TIS") |
| ATM | air traffic management |
| ATN | aeronautical telecommunication network |
| ATP | at... (followed by time or place) |
| ATS | air traffic services |
| ATTN | attention |
| AT-VASIS | abbreviated T visual approach slope indicator system (to be pronounced "AY-TEE-VASIS") |
| ATZ | aerodrome traffic zone |
| AUG | August |
| AUP* | airspace use plan |
| AUTH | authorized or authorization |
| AUTO | automatic |
| AUW | all up weight |
| AUX | auxiliary |
| AVBL | available or availability |
| AVG | average |
| AVGAS | aviation gasoline |
| AWOS | automated weather observation system |
| AWTA | advise at what time able |
| AWY | airway |
| AZM | azimuth |
| B - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| B | blue |
| BA | braking action |
| BARO-VNAV | barometric vertical navigation (to be pronounced "BAA-RO-VEENAV") |
| BASE | cloud base |
| BCFG | fog patches |
| BCN | beacon (aeronautical ground light) |
| BCST | broadcast |
| BDRY | boundary |
| BECMG | becoming |
| BFR | before |
| BKN | broken |
| BL | blowing (followed by DU=dust, SA=sand or SN=snow) |
| BLDG | building |
| BLO | below clouds |
| BLW | below... |
| BOMB | bombing |
| BR | mist |
| BRF | short (used to indicate the type of approach desired or required) |
| BRG | bearing |
| BRKG | braking |
| BS | commercial broadcasting station |
| BTL | between layers |
| BTN | between |
| BUFR | binary universal form for the representation of meteorological data |
| C - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| C | centre (preceded by runway designation number to identify a parallel runway) |
| C | degrees Celsius (centigrade) |
| CA | course to an altitude |
| CAA | civil aviation authority or civil aviation administration |
| CADF* | centralized airspace data function |
| CAT | category |
| CAT | clear air turbulence |
| CAVOK | visibility, cloud and present weather better than prescribed values or conditions (to be pronounced "KAV-OH-KAY") |
| CB | cumulonimbus (to be pronounced "CEE BEE") |
| CBA* | cross border area |
| CC | cirrocumulus |
| CCA | (or CCB, CCC...etc., in sequence) corrected meteorological message (message type designator) |
| CCO | continuous climb operations |
| CD | candela |
| CDA* | continuous descent approach |
| CDM* | collaborative decision making |
| CDN | co-ordination (message type designator) |
| CDO | continuous descent operations |
| CDR* | conditional route |
| CF | change frequency to... |
| CF | course to a fix |
| CFM | confirm or I confirm (to be used in AFS as a procedure signal) |
| CGL | circling guidance light(s) |
| CH | channel |
| CH | this is a channel-continuity-check of transmission to permit comparison of your record of channel-sequence numbers of messages received on the channel (to be used in AFS as a procedure signal) |
| CHEM | chemical |
| CHG | modification (message type designator) |
| CI | cirrus |
| CIDIN | common ICAO data interchange network |
| CIV | civil |
| CK | check |
| CL | centre line |
| CLA | clear type of ice formation |
| CLBR | calibration |
| CLD | cloud |
| CLG | calling |
| CLIMB-OUT | climb-out area |
| CLR | clear(s) or cleared to... or clearance |
| CLRD | runway(s) cleared (used in METAR/SPECI) |
| CLSD | close or closed or closing |
| CM | centimetre |
| CMB | climb to or climbing to |
| CMPL | completion or completed or complete |
| CNL | cancel or cancelled |
| CNL | flight plan cancellation (message type designator) |
| CNS | communications, navigation and surveillance |
| COM | communications |
| CONC | concrete |
| COND | condition |
| CONS | continuous |
| CONST | construction or constructed |
| CONT | continue(s) or continued |
| COOR | co-ordinate or co-ordination |
| COORD | co-ordinates |
| COP | change-over point |
| COR | correct or correction or corrected (used to indicate corrected meteorological message; message type designator) |
| COT | at the coast |
| COV | cover or covered or covering |
| CPDLC | controller-pilot data link communications |
| CPL | current flight plan (message type designator) |
| CRC | cyclic redundancy check |
| CRM | collision risk model |
| CRP | compulsory reporting point |
| CRZ | cruise |
| CS | call sign |
| CS | cirrostratus |
| CTA | control area |
| CTAM | climb to and maintain |
| CTC | contact |
| CTL | control |
| CTN | caution |
| CTOT* | calculated take-off time |
| CTR | control zone |
| CU | cumulus |
| CUF | cumuliform |
| CUST | customs |
| CVR | cockpit voice recorder |
| CW | continuous wave |
| CWY | clearway |
| D - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| D | danger area (followed by identification) |
| D | downward (tendency in RVR during previous 10 minutes) |
| D* | FRA departure connecting point |
| DA | decision altitude |
| D-ATIS | data link automatic terminal information service (to be pronounced "DEE-ATIS") |
| DCD | double channel duplex |
| DCKG | docking |
| DCP | datum crossing point |
| DCPC | direct controller-pilot communications |
| DCS | double channel simplex |
| DCT | direct (in relation to flight plan clearances and type of approach) |
| DE | from (used to precede the call sign of the calling station) (to be used in AFS as a procedure signal) |
| DEC | December |
| DEG | degrees |
| DEP | depart or departure |
| DEP | departure (message type designator) |
| DEPO | deposition |
| DER | departure end of the runway |
| DES | descend to or descending to |
| DEST | destination |
| DETRESFA | distress phase |
| DEV | deviation or deviating |
| DF | direction finding |
| DFDR | digital flight data recorder |
| DFTI | distance from touchdown indicator |
| DH | decision height |
| DIF | diffuse |
| DIST | distance |
| DIV | divert or diverting |
| DLA | delay or delayed |
| DLA | delay (message type designator) |
| DLIC | data link initiation capability |
| DLY | daily |
| DME | distance measuring equipment |
| DNG | danger or dangerous |
| DOF | date of flight |
| DOM | domestic |
| DP | dew point temperature |
| DPT | depth |
| DR | dead reckoning |
| DR | low drifting (followed by DU=dust, SA=sand or SN=snow) |
| DRG | during |
| DS | duststorm |
| DSB | double sideband |
| DTAM | descend to and maintain |
| DTG | date-time group |
| DTHR | displaced runway threshold |
| DTRT | deteriorate or deteriorating |
| DTW | dual tandem wheels |
| DU | dust |
| DUC | dense upper cloud |
| DUPE | this is a duplicate message (to be used in AFS as a procedure signal) |
| DUR | duration |
| D-VOLMET | data link VOLMET |
| DVOR | Doppler VOR |
| DVORTAC* | Doppler VOR and TACAN |
| DW | dual wheels |
| DZ | drizzle |
| E - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| E | east or eastern longitude |
| E* | FRA horizontal entry point |
| EASA* | European Aviation Safety Agency |
| EAT | expected approach time |
| EAUP* | European airspace use plan |
| EB | eastbound |
| ECAC* | European civil aviation conference |
| EDA | elevation differential area |
| EDTO | extended diversion time operation |
| EEE | error (to be used in AFS as a procedure signal) |
| EET | estimated elapsed time |
| EFC | expect further clearance |
| EFCT* | expected further clearance time |
| EFIS | electronic flight instrument system (to be pronounced "EE-FIS") |
| EGNOS | European geostationary navigation overlay service (to be pronounced "EGG-NOS") |
| EHF | extremely high frequency (30 000 to 300 000 MHz) |
| ELBA | emergency location beacon - aircraft |
| ELEV | elevation |
| ELR | extra long range |
| ELT | emergency locator transmitter |
| EM | emission |
| EMBD | embedded in a layer (to indicate cumulonimbus embedded in layers of other clouds) |
| EMERG | emergency |
| En* | English |
| END | stop-end (related to RVR) |
| ENE | east-north-east |
| ENG | engine |
| ENR | en-route |
| ENRC | en-route chart (followed by name/title) |
| EOBT | estimated off-block time |
| EQPT | equipment |
| ESE | east-south-east |
| EST | estimate or estimated or estimate (as message type designator) |
| ETA | estimated time of arrival or estimating arrival |
| ETD | estimated time of departure or estimating departure |
| ETO | estimated time over significant point |
| EUR RODEX | European regional OPMET data exchange |
| EUUP* | European updated airspace use plan |
| EV | every |
| EVS | enhanced vision system |
| EXC | except |
| EXER | exercises or exercising or to exercise |
| EXP | expect or expected or expecting |
| EXTD | extend or extending or extended |
| F - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| F | fixed |
| FA | course from a fix to an altitude |
| FAC | facilities |
| FAF | final approach fix |
| FAL | facilitation of international air transport |
| FANS* | future air navigation system |
| FAP | final approach point |
| FAS | final approach segment |
| FATO | final approach and take-off area |
| FAVA* | final approach vectoring area |
| FAX | facsimile transmission |
| FBL | light (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA=light rain) |
| FBZ* | flight planning buffer zone |
| FC | funnel cloud (tornado or water spout) |
| FCST | forecast |
| FCT | friction coefficient |
| FDPS | flight data processing system |
| FEB | February |
| FEW | few |
| FG | fog |
| FIC | flight information centre |
| FIO* | flight information office |
| FIR | flight information region |
| FIS | flight information service |
| FISA | automated flight information service |
| Fl* | flashing |
| FL | flight level |
| FLD | field |
| FLG | flashing |
| FLR | flares |
| FLT | flight |
| FLTCK | flight check |
| FLUC | fluctuating or fluctuation or fluctuated |
| FLW | follow(s) or following |
| FLY | fly or flying |
| FM | course from a fix to manual termination (used in navigation database coding) |
| FM | from |
| FM | from (followed by time weather change is forecast to begin) |
| FMC | flight management computer |
| FMC* | frequency monitoring code |
| FMP* | flow management position |
| FMS | flight management system |
| FMU | flow management unit |
| FNA | final approach |
| FPAP | flight path alignment point |
| FPL | flight plan |
| FPM | feet per minute |
| FPR | flight plan route |
| FR | fuel remaining |
| FRA* | free route airspace |
| FREQ | frequency |
| FRI | Friday |
| FRNG | firing |
| FRONT | front (relating to weather) |
| FROST | frost (used in aerodrome warnings) |
| FRQ | frequent |
| FSC* | flight service centre |
| FSL | full stop landing |
| FSS | flight service station |
| FST | first |
| ft | feet (dimensional unit) |
| FT | feet (dimensional unit) |
| FTE | flight technical error |
| FTP | fictitious threshold point |
| FTT | flight technical tolerance |
| FU | smoke |
| FUA* | flexible use of airspace |
| FZ | freezing |
| FZDZ | freezing drizzle |
| FZFG | freezing fog |
| FZRA | freezing rain |
| G - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| G | green |
| G | variations from the mean wind speed (gusts) (followed by figures in METAR/SPECI and TAF) |
| GA | general aviation |
| GA | go ahead, resume sending (to be used in AFS as a procedure signal) |
| G/A | ground-to-air |
| G/A/G | ground-to-air and air-to-ground |
| GAGAN | GPS and geostationary earth orbit augmented navigation |
| GAIN | airspeed or headwind gain |
| GAMET | area forecast for low-level flights |
| GARP | GBAS azimuth reference point |
| GAT* | general air traffic |
| GBAS | ground-based augmentation system (to be pronounced "GEE-BAS") |
| GCA | ground controlled approach system or ground controlled approach |
| GEN | general |
| GEO | geographic or true |
| GES | ground earth station |
| GHz* | giga Hertz (= 1000 MHz) |
| GLD | glider |
| GLLFC* | graphical low-level forecast |
| GLONASS | global orbiting navigation satellite system (to be pronounced "GLO-NAS") |
| GLS | GBAS landing system |
| GLV* | groep lichte vliegtuigen |
| GMC | ground movement chart (followed by name/title) |
| GND | ground |
| GNDCK | ground check |
| GNSS | global navigation satellite system |
| GOV | government |
| GP | glide path |
| GPA | glide path angle |
| GPIP | glide path intercept point |
| GPS | global positioning system |
| GPU | ground power unit |
| GPWS | ground proximity warning system |
| GR | hail |
| GRAS | ground-based regional augmentation system (to be pronounced "GRASS") |
| GRASS | grass landing area |
| GRIB | processed meteorological data in the form of grid point values expressed in binary form (meteorological code) |
| GRVL | gravel |
| GS | ground speed |
| GS | small hail and/or snow pellets |
| GUND | geoid undulation |
| H - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| H | high pressure area or the centre of high pressure |
| H | significant wave height (followed by figures in METAR/SPECI) |
| H* | hourly |
| h* | half-hourly |
| H24 | continuous day and night service |
| HA | holding/racetrack to an altitude |
| HAP* | heli aiming point |
| HAPI | helicopter approach path indicator |
| HBN | hazard beacon |
| HCH | helicopter crossing height |
| HDF | high frequency direction finding station |
| HDG | heading |
| HEL | helicopter |
| HEMS* | helicopter emergency medical service |
| HF | high frequency (3000 to 30 000 kHz) |
| HF | holding/racetrack to a fix |
| HGT | height or height above |
| HJ | sunrise to sunset |
| HLDG | holding |
| HLP | heliport |
| HLS | helicopter landing site |
| HM | holding/racetrack to a manual termination |
| HMR* | helicopter main route |
| HN | sunset to sunrise |
| HO | service available to meet operational requirements |
| HOL | holiday |
| HOSP | hospital aircraft |
| hPa | hectopascal |
| HPZ* | helicopter protection zone |
| HR | hours |
| HRP | heliport reference point |
| HS | service available during hours of scheduled operations |
| HTZ* | helicopter traffic zone |
| HUD | head-up display |
| HUM | humanitarian |
| HURCN | hurricane |
| 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, e.g. HVY RA=heavy rain) |
| HX | no specific working hours |
| HYR | higher |
| HZ | haze |
| Hz | Hertz (cycle per second) |
| I - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| I* | FRA intermediate point |
| IAC | instrument approach chart (followed by name/title) |
| IAF | initial approach fix |
| IAO | in and out of clouds |
| IAP | instrument approach procedure |
| IAR | intersection of air routes |
| IAS | indicated airspeed |
| IBN | identification beacon |
| ICAO* | International Civil Aviation Organization |
| ICE | icing |
| ID | identifier or identify |
| IDENT | identification |
| IF | intermediate approach fix |
| IFF | identification friend/foe |
| IFPS* | integrated initial flight plan processing system |
| IFR | instrument flight rules |
| IGA | international general aviation |
| ILS | instrument landing system |
| IM | inner marker |
| IMC | instrument meteorological conditions |
| IMG | immigration |
| IMI | interrogation sign (question mark) (to be used in AFS as a procedure signal) |
| IMPR | improve or improving |
| IMT | immediate or immediately |
| INA | initial approach |
| INBD | inbound |
| INC | in cloud |
| INCERFA | uncertainty phase |
| INCORP | incorporated |
| INFO | information |
| INOP | inoperative |
| INP | if not possible |
| INPR | in progress |
| INS | inertial navigation system |
| INSTL | install or installed or installation |
| INSTR | instrument |
| INT | intersection |
| INTL | international |
| INTRG | interrogator |
| INTRP | interrupt or interruption or interrupted |
| INTSF | intensify or intensifying |
| INTST | intensity |
| IR | ice on runway |
| IRS | inertial reference system |
| ISA | international standard atmosphere |
| ISB | independent sideband |
| ISOL | isolated |
| J - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| JAA* | joint aviation authorities |
| JAN | January |
| JRCC* | joint rescue co-ordination centre |
| JTST | jet stream |
| JUL | July |
| JUN | June |
| K - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| kg | kilograms |
| KG | kilograms |
| kHz | kilohertz |
| KIAS | knots indicated airspeed |
| km | kilometres |
| KM | kilometres |
| kmH | kilometres per hour |
| kPa | kilopascal |
| KT | knots |
| kW | kilowatts |
| L - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| L | left (preceded by runway designation number to identify a parallel runway) |
| L* | light (weight) |
| L | litre |
| L | locator |
| L | low pressure area or the centre of low pressure |
| LAM | logical acknowledgement (message type designator) |
| LAN | inland |
| LAT | latitude |
| LB* | pounds (weight) |
| LCA | local or locally or location or located |
| LCN* | load classification number |
| LDA | landing distance available |
| LDAH | landing distance available, helicopter |
| LDG | landing |
| LDI | landing direction indicator |
| LEN | length |
| LF | low frequency (30 to 300 kHz) |
| LGT | light or lighting |
| LGTD | lighted |
| LIH | light intensity high |
| LIL | light intensity low |
| LIM | light intensity medium |
| LINE | line (used in SIGMET) |
| LLFC* | low-level forecast |
| LLTI* | low-level temperature inversion |
| LM | locator, middle |
| LMT | local mean time |
| LNAV | lateral navigation (to be pronounced "EL-NAV") |
| LNG | long (used to indicate the type of approach desired or required) |
| LO | locator, outer |
| LOC | localizer |
| LONG | longitude |
| LORAN | LORAN (long range air navigation system) |
| LOSS | airspeed or headwind loss |
| LPV | localizer performance with vertical guidance |
| LR | the last message received by me was... (to be used in AFS as a procedure signal) |
| LRG | long range |
| LS | the last message sent by me was... or last message was... (to be used in AFS as a procedure signal) |
| LTA | lower control area |
| LTD | limited |
| LTP | landing threshold point |
| LV | light and variable (relating to wind) |
| LVE | leave or leaving |
| LVL | level |
| LVNL* | Luchtverkeersleiding Nederland |
| LVP | low visibility procedures |
| LYR | layer or layered |
| M - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| m | metres (preceded by figures) |
| M | metres (preceded by figures) |
| M | mach number (followed by figures) |
| M | minimum value of runway visual range (followed by figures in METAR/SPECI) |
| M* | medium |
| MAA | maximum authorized altitude |
| MAG | magnetic |
| MAHF | missed approach holding fix |
| MAINT | maintenance |
| MAP | aeronautical maps and charts |
| MAPT | missed approach point |
| MAR | at sea |
| MAR | March |
| MATF | missed approach turning fix |
| MATZ | military aerodrome traffic zone |
| MAX | maximum |
| MAY | May |
| MBST | microburst |
| MCA | minimum crossing altitude |
| MCTR | military control zone |
| MCW | modulated continuous wave |
| MDA | minimum descent altitude |
| MDF | medium frequency direction finding station |
| MDH | minimum descent height |
| MEA | minimum en-route altitude |
| MEDEVAC | medical evacuation flight |
| MEHT | minimum eye height over threshold (for visual approach slope indicator systems) |
| MET | meteorological or meteorology |
| METAR | aerodrome routine meteorological report (in meteorological code) |
| MET REPORT | local routine meteorological report (in abbreviated plain language) |
| MF | medium frequency (300 to 3000 kHz) |
| MFA* | minimum flight altitude |
| MHA | minimum holding altitude |
| MHDF | medium and high frequency direction finding stations (at the same location) |
| MHVDF | medium, high and very high frequency direction finding stations (at the same location) |
| MHz | megahertz |
| MID | mid-point (related to RVR) |
| MIFG | shallow fog |
| MIL | military |
| MILATCC* | military air traffic control centre |
| MIN | minutes |
| MIS | missing... (transmission identification) (to be used in AFS as a procedure signal) |
| MKR | marker radio beacon |
| MLA* | microlight aeroplane |
| MLH* | microlight helicopter |
| MLS | microwave landing system |
| MLW* | maximum certificated landing weight |
| MM | middle marker |
| MNM | minimum |
| MNPS | minimum navigation performance specifications |
| MNT | monitor or monitoring or monitored |
| MNTN | maintain |
| MOA | military operating area |
| MOC | minimum obstacle clearance (required) |
| MOCA | minimum obstacle clearance altitude |
| MOD | moderate (used to indicate the intensity of weather phenomena, interference of static reports, e.g. MODRA=moderate rain) |
| MOGAS* | motor gasoline (premiumgrade or fourstar) |
| MON | above mountains |
| MON | Monday |
| MOPS | minimum operational performance standards |
| MOV | move or moving or movement |
| MPa* | megapascal |
| MPS | metres per second |
| MRA | minimum reception altitude |
| MRG | medium range |
| MRP | ATS/MET reporting point |
| MRVA* | minimum radar vector altitude |
| MS | minus |
| MSA | minimum sector altitude |
| MSAS | multi-functional transport satellite (MTSAT) satellite-based augmentation system (to be pronounced "EM-SAS") |
| MSAW | minimum safe altitude warning |
| MSG | message |
| MSL | mean sea level |
| MSR | message... (transmission identification) has been misrouted (to be used in AFS as a procedure signal) |
| MSSR | monopulse secondary surveillance radar |
| MT | mountain |
| MTI* | marked temperature inversion |
| MTOM | maximum take-off mass |
| MTU | metric units |
| MTW | mountain waves |
| MUAC* | Maastricht Upper Area Control centre |
| MVA* | minimum vectoring altitudes |
| MVDF | medium and very high frequency direction finding stations (at the same location) |
| MWO | meteorological watch office |
| MX | mixed type of ice formation (white and clear) |
| N - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| N | no distinct tendency (in RVR during previous 10 minutes) |
| N | north or northern latitude |
| NA* | not applicable |
| NADP | noise abatement departure procedure |
| NAF* | North Sea Area Forecast |
| NASC | national AIS system centre |
| NAT | North Atlantic |
| NAV | navigation |
| NAVAID | navigation aid |
| NB | northbound |
| NBFR | not before |
| NC | no change |
| NCD | no cloud detected (used in automated METAR/SPECI) |
| NDB | non-directional radio beacon |
| NDV | no directional variations available (used in automated METAR/SPECI) |
| NE | north-east |
| NEB | north-eastbound |
| NEG | no or negative or permission not granted or that is not correct |
| NGT | night |
| NIL | none or I have nothing to send to you |
| NM | nautical miles |
| NML | normal |
| NMOC* | Network Manager Operation Center |
| NN | no name, unnamed |
| NNE | north-north-east |
| NNW | north-north-west |
| NO | no (negative) (to be used in AFS as a procedure signal) |
| NOF | international NOTAM office |
| NONSTD | non-standard |
| NOSIG | no significant change (used in trend-type landing forecasts) |
| NOTAM | a notice distributed by means of telecommunication 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 |
| NOTAMC | cancelling NOTAMN |
| NOTAMN | new NOTAM |
| NOTAMR | replacing NOTAM |
| NOV | November |
| NOZ | normal operating zone |
| NPA | non-precision approach |
| NR | number |
| NRH | no reply heard |
| NS | nimbostratus |
| NSC | nil significant cloud |
| NSE | navigation system error |
| NSW | nil significant weather |
| NTL | national |
| NTZ | no transgression zone |
| NU* | not usable |
| NW | north-west |
| NW* | nieuw in "Nw Milligen" |
| NWB* | north-westbound |
| NXT | next |
| O - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| OAC | oceanic area control centre |
| OAS | obstacle assessment surface |
| OAT* | operational air traffic (military) |
| OBS | observe or observed or observation |
| OBSC | obscure or obscured or obscuring |
| OBST | obstacle |
| OCA | obstacle clearance altitude |
| OCA | oceanic control area |
| OCC | occulting (light) |
| OCH | obstacle clearance height |
| OCNL | occasional or occasionally |
| OCS | obstacle clearance surface |
| OCT | October |
| OFZ | obstacle free zone |
| OGN | originate (to be used in AFS as a procedure signal) |
| OHD | overhead |
| OIS | obstacle identification surface |
| OK | we agree or it is correct (to be used in AFS as a procedure signal) |
| OLDI | online data interchange |
| OM | outer marker |
| OPA | opaque, white type of ice formation |
| OPC | control indicated is operational control |
| OPMET | operational meteorological (information) |
| OPN | open or opening or opened |
| OPR | operator or operate or operative or operating or operational |
| OPS | operations |
| O/R | on request |
| ORD | order |
| OSV | ocean station vessel |
| OTP | on top |
| OTS | organized track system |
| OUBD | outbound |
| OVC | overcast |
| P - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| P | maximum value of wind speed or runway visual range (followed by figures in METAR/SPECI and TAF) |
| P | prohibited area (followed by identification) |
| PA | precision approach |
| PALS | precision approach lighting system (specify category) |
| PANS | procedures for air navigation services |
| PAPI | precision approach path indicator |
| PAR | precision approach radar |
| PARL | parallel |
| PATC | precision approach terrain chart (followed by name/title) |
| PAX | passenger(s) |
| PBC | performance-based communication |
| PBN | performance-based navigation |
| PBS | performance-based surveillance |
| PCD | proceed or proceeding |
| PCL | pilot-controlled lighting |
| PCN | pavement classification number |
| PCR | pavement classification rating |
| PCT | per cent |
| PDC | pre-departure clearance |
| PDG | procedure design gradient |
| PDT* | procedure design tool |
| PER | performance |
| PERM | permanent |
| PFC* | porous friction course |
| PIB | pre-flight information bulletin |
| PJE | parachute jumping exercise |
| PL* | plain language |
| PL | ice pellets |
| PLA | practice low approach |
| PLVL | present level |
| PN | prior notice required |
| PNR | point of no return |
| PO | dust/sand whirls (dust devils) |
| POB | persons on board |
| POSS | possible |
| PPI | plan position indicator |
| PPR | prior permission required |
| PPSN | present position |
| PRFG | aerodrome partially covered by fog |
| PRI | primary |
| PRKG | parking |
| PROB | probability |
| PROC | procedure |
| PROP | propeller |
| PROV | provisional |
| PRP | point-in-space reference point |
| PS | plus |
| PSI* | pounds per square inch |
| PSG | passing |
| PSN | position |
| PSP | pierced steel plank |
| PSR | primary surveillance radar |
| PSYS | pressure system(s) |
| PTN | procedure turn |
| PTS | polar track structure |
| PWR | power |
| Q - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| QDL | do you intend to ask me for a series of bearings? or I intend to ask you for a series of bearings (to be used in radiotelegraphy as a Q code) |
| QDM | magnetic heading (zero wind) |
| QDR | magnetic bearing |
| QFE | atmospheric pressure at aerodrome elevation (or at runway threshold) |
| QFU | magnetic orientation of runway |
| QGE | what is my distance to your station? or your distance to my station is (distance figures and units) (to be used in radiotelegraphy as a Q code) |
| QJH | shall I run my test tape/a test sentence? or run your test tape/a test sentence (to be used in AFS as a Q code) |
| QNH | altimeter sub-scale setting to obtain elevation when on the ground |
| QSP | will you relay to... free of charge? or I will relay to... free of charge (to be used in AFS as a Q code) |
| QTA | shall I cancel telegram number...? or cancel telegram number... (to be used in AFS as a Q code) |
| QTE | true bearing |
| QTF | will you give me the position of my station according to the bearings taken by the D/F stations which you control? or the position of your station according to the bearings taken by the D/F stations that I control was... latitude... longitude (or other indication of position), class... at... hours (to be used in radiotelegraphy as a Q code) |
| QUAD | quadrant |
| QUJ | will you indicate the TRUE track to reach you? or the TRUE track to reach me is... degrees at... hours (to be used in radiotelegraphy as a Q code) |
| R - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| R | radial from VOR (followed by three figures) |
| R | rate of turn |
| R | received (acknowledgement of receipt) (to be used in AFS as a procedure signal) |
| R | red |
| R | restricted area (followed by identification) |
| R | right (preceded by runway designation number to identify a parallel runway) |
| R | runway (followed by figures in METAR/SPECI) |
| RA | rain |
| RA | resolution advisory |
| RAC | rules of the air and air traffic services |
| RAD* | route availability document |
| RAG | ragged |
| RAG | runway arresting gear |
| RAI | runway alignment indicator |
| RAIM | receiver autonomous integrity monitoring |
| RAPCON* | radar approach control |
| RASC | regional AIS system centre |
| RASS | remote altimeter setting source |
| RB | rescue boat |
| RCA | reach cruising altitude |
| RCAM* | runway condition assessment matrix |
| RCC | rescue co-ordination centre |
| RCF | radio communication failure (message type designator) |
| RCH | reach or reaching |
| RCL | runway centre line |
| RCLL | runway centre line light(s) |
| RCLR | recleared |
| RCP | required communication performance |
| RCR* | runway condition report |
| RDH | reference datum height |
| RDL | radial |
| RDO | radio |
| RDOACT | radioactive |
| RE | recent (used to qualify weather phenomena e.g. RERA=recent rain) |
| REC | receive or receiver |
| RECAT-EU* | European wake vortex re-categorization |
| REDL | runway edge light(s) |
| REF | reference to... or refer to ... |
| REG | registration |
| RENL | runway end light(s) |
| REP | report or reporting or reporting point |
| REQ | request or requested |
| RERTE | re-route |
| RESA | runway end safety area |
| RETD* | revised estimated time of departure |
| RF | constant radius arc to a fix |
| RFFS | rescue and fire fighting services |
| RFP* | replacement flight plan |
| RG | range (lights) |
| RHC | right-hand circuit |
| RIF | reclearance in flight |
| RIME | rime (used in aerodrome warnings) |
| RL | report leaving |
| RLA | relay to |
| RLCE | request level change en-route |
| RLLS | runway lead-in lighting system |
| RLNA | request level not available |
| RMK | remark |
| RMZ* | radio mandatory zone |
| RNAV | area navigation (to be pronounced "AR-NAV") |
| RNG | radio range |
| RNLAF* | Royal Netherlands Airforce |
| RNN* | Royal Netherlands Navy |
| RNP | required navigation performance |
| ROBEX | regional OPMET bulletin exchange (scheme) |
| ROC | rate of climb |
| ROD | rate of descent |
| RON | receiving only |
| RPAS* | remotely piloted aircraft systems |
| RPDS | reference path data selector |
| RPI | radar position indicator |
| RPL | repetitive flight plan |
| RPLC | replace or replaced |
| RPS | radar position symbol |
| RPT | repeat or I repeat (to be used in AFS as a procedure signal) |
| RQ | request (to be used in AFS as a procedure signal) |
| RQMNTS | requirements |
| RQP | request flight plan (message type designator) |
| RQS | request supplementary flight plan (message type designator) |
| RR | report reaching |
| RRA | (or RRB, RRC...etc., in sequence) delayed meteorological message (message type designator) |
| RSA* | restricted airspace |
| RSC | rescue sub-centre |
| RSCD | runway surface condition |
| RSM* | runway state message |
| RSP | required surveillance performance |
| RSP | responder beacon |
| RSR | en-route surveillance radar |
| RSS | root sum square |
| RTD | delayed (used to indicate delayed meteorological message; message type designator) |
| RTE | route |
| RTF | radiotelephone |
| RTG | radiotelegraph |
| RTHL | runway threshold light(s) |
| RTN | return or returned or returning |
| RTODAH | rejected take-off distance available, helicopter |
| RTS | return to service |
| RTT | radioteletypewriter |
| RTZL | runway touchdown zone light(s) |
| RUT | standard regional route transmitting frequencies |
| RV | rescue vessel |
| RVA | radar vectoring area |
| RVR | runway visual range |
| RVSM | reduced vertical separation minimum (300 m (1000 ft)) between FL 290 and FL 410 |
| RWY | runway |
| RWYCC* | runway condition code |
| S - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| S | south or southern latitude |
| S* | special meteorological report (in abbreviated plain language) |
| S | state of the sea (followed by figures in METAR/SPECI) |
| SA | sand |
| SALS | simple approach lighting system |
| SAN | sanitary |
| SAR | search and rescue |
| SARPS | standards and recommended practices (ICAO) |
| SAT | Saturday |
| SATCOM | satellite communication (used only when referring generally to both voice and data satellite communication or only data satellite communication) |
| SATVOICE | satellite voice communication |
| SB | southbound |
| SBAS | satellite-based augmentation system (to be pronounced "ESS-BASS") |
| SC | stratocumulus |
| SCT | scattered |
| SD | standard deviation |
| SDBY | stand by |
| SDF | step down fix |
| SE | south-east |
| SEA | sea (used in connection with sea-surface temperature and state of the sea) |
| SEB | south-eastbound |
| SEC | seconds |
| SECN | section |
| SECT | sector |
| SELCAL | selective calling system |
| SEP | September |
| SER | service or servicing or served |
| SERA* | standardised European rules of the air |
| SEV | severe (used e.g. to qualify icing and turbulence reports) |
| SFC | surface |
| SG | snow grains |
| SGL | signal |
| SH | showers (followed by RA=rain, SN=snow, PL=ice pellets, GR=hail, GS=small hail and/or snow pellets or combinations thereof, e.g. SHRASN=showers of rain and snow) |
| SHF | super high frequency (3000 to 30 000 MHz) |
| SI | international system of units |
| SID | standard instrument departure |
| SIF | selective identification feature |
| SIG | significant |
| SIGMET | information concerning en-route weather and other phenomena in the atmosphere that may affect the safety of aircraft operations |
| SIMUL | simultaneous or simultaneously |
| SIWL | single isolated wheel load |
| SKED | schedule or scheduled |
| SLP | speed limiting point |
| SLW | slow |
| SMC | surface movement control |
| SMR | surface movement radar |
| SN | snow |
| SNOCLO | aerodrome closed due to snow (used in METAR/SPECI) |
| SNOWTAM | 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 format |
| SOC | start of climb |
| SPECI | aerodrome special meteorological report (in meteorological code) |
| SPECIAL | special local meteorological report (in abbreviated plain language) |
| SPI | special position indicator |
| SPL | supplementary flight plan (message type designator) |
| SPOC | SAR point of contact |
| SPOT | spot wind |
| SQ | squall |
| SQL | squall line |
| SR | sunrise |
| SR-30* | 30 minutes before sunrise |
| SRA | surveillance radar approach |
| SRE | surveillance radar element of precision approach radar system |
| SRG | short range |
| SRR | search and rescue region |
| SRY | secondary |
| SS | sandstorm |
| SS | sunset |
| SS+30* | 30 minutes after sunset |
| SSB | single sideband |
| SSE | south-south-east |
| SSR | secondary surveillance radar |
| SST | supersonic transport |
| SSW | south-south-west |
| ST | stratus |
| STA | straight-in approach |
| STAR | standard instrument arrival |
| STD | standard |
| STF | stratiform |
| STN | station |
| STNR | stationary |
| STOL | short take-off and landing |
| STS | status |
| STWL | stopway light(s) |
| SUBJ | subject to |
| SUN | Sunday |
| SUP | supplement (AIP supplement) |
| SUPPS | regional supplementary procedures |
| SVC | service (message type only) |
| SVCBL | serviceable |
| SW | south-west |
| SWB | south-westbound |
| SWC* | significant weather chart |
| SWY | stopway |
| T - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| T | temperature |
| T | true (preceded by a bearing to indicate reference to true north) |
| TA | traffic advisory |
| TA | transition altitude |
| TAA | terminal arrival altitude |
| TACAN | UHF tactical air navigation aid |
| TAF | aerodrome forecast (in meteorological code) |
| TA/H | turn at an altitude/height |
| TAIL | tail wind |
| TAR | terminal area surveillance radar |
| TAS | true airspeed |
| TAX | taxiing or taxi |
| TBS* | Time based separation |
| TC | tropical cyclone |
| TCAC | tropical cyclone advisory centre |
| TCAS RA | traffic alert and collision avoidance system resolution advisory (to be pronounced "TEE-CAS-AR-AY") |
| TCH | threshold crossing height |
| TCU | towering cumulus |
| TDO | tornado |
| TDZ | touchdown zone |
| TECR | technical reason |
| TEL | telephone |
| TEMPO | temporary or temporarily |
| TF | track to fix |
| TFC | traffic |
| TGL | touch-and-go landing |
| TGL* | temporary guidance leaflet |
| TGS | taxiing guidance system |
| THR | threshold |
| THRU | through |
| THU | Thursday |
| TIBA | traffic information broadcast by aircraft |
| TIL | until |
| TIP | until past... (place) |
| TKOF | take-off |
| TL | till (followed by time by which weather change is forecast to end) |
| TLOF | touchdown and lift-off area |
| TMA | terminal control area |
| TMG* | touring motor glider |
| TMZ* | transponder mandatory zone |
| TN | minimum temperature (followed by figures in TAF) |
| TNA | turn altitude |
| TNH | turn height |
| TO | to... (place) |
| TOBT* | target off-block time |
| TOC | top of climb |
| TODA | take-off distance available |
| TODAH | take-off distance available, helicopter |
| TOP | cloud top |
| TORA | take-off run available |
| TOX | toxic |
| TP | turning point |
| TR | track |
| TRA | temporary reserved airspace |
| TRANS | transmits or transmitter |
| TREND | trend forecast |
| TRG | training |
| TRL | transition level |
| TROP | tropopause |
| TS | thunderstorm (in aerodrome reports and forecasts, TS used alone means thunder heard but no precipitation at the aerodrome) |
| TS | thunderstorm (followed by RA=rain, SN=snow, PL=ice pellets, GR=hail GS=small hail and/or snow pellets or combinations thereof, e.g. TSRASN=thunderstorm with rain and snow) |
| TSA* | temporary segregated area |
| TSAT* | target start-up approval time |
| TSUNAMI | tsunami (used in aerodrome warnings) |
| TT | teletypewriter |
| TUE | Tuesday |
| TURB | turbulence |
| T-VASIS | T visual approach slope indicator system (to be pronounced "TEE-VASIS") |
| TVOR | terminal VOR |
| TWR | aerodrome control tower or aerodrome control |
| TWY | taxiway |
| TX | maximum temperature (followed by figures in TAF) |
| TXL | taxilane |
| TXT | text (when the abbreviation is used to request a repetition, the question mark (IMI) precedes the abbreviation, e.g. IMI TXT) (to be used in AFS as a procedure signal) |
| TYP | type of aircraft |
| TYPH | typhoon |
| U - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| U | upward (tendency in RVR during previous 10 minutes) |
| UA | unmanned aircraft |
| UAB | until advised by ... |
| UAC | upper area control centre |
| UAR | upper air route |
| UAS | unmanned aircraft system |
| UDA* | upper advisory area |
| UDF | ultra high frequency direction finding station |
| UDP* | uniform daylight period |
| UDR* | upper advisory route |
| UFN | until further notice |
| UHDT | unable higher due traffic |
| UHF | ultra high frequency (300 to 3000 MHz) |
| UIC | upper information centre |
| UIR | upper flight information region |
| ULM | ultra light motorized aircraft |
| ULR | ultra long range |
| UNA | unable |
| UNAP | unable to approve |
| UNL | unlimited |
| UNREL | unreliable |
| UP | unidentified precipitation (used in METAR/SPECI) |
| URL* | uniform resource locator |
| U/S | unserviceable |
| UTA | upper control area |
| UTC | co-ordinated universal time |
| UUP* | updated airspace use plan |
| V - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| V | variations from the mean wind direction (preceded and followed by figures in METAR/SPECI, e.g. 350V070) |
| VA | heading to an altitude |
| VA | volcanic ash |
| VAAC | volcanic ash advisory centre |
| VAC | visual approach chart (followed by name/title) |
| VAL | in valleys |
| VAN | runway control van |
| VAR | magnetic variation |
| VAR | visual-aural radio range |
| VASIS | visual approach slope indicator systems |
| VB* | during day when visibility is bad |
| VC | vicinity of the aerodrome (followed by FG=fog, FC=funnel cloud, SH=showers, PO=dust/sand whirls, BLDU=blowing dust, BLSA=blowing sand, BLSN=blowing snow, DS=duststorm, SS=sandstorm, TS=thunderstorm or VA=volcanic ash, e.g. VCFG=vicinity fog) |
| VCY | vicinity |
| VDF | very high frequency direction finding station |
| VDGS* | visual docking guidance system |
| VER | vertical |
| VFR | visual flight rules |
| VHF | very high frequency (30 to 300 MHz) |
| VI | heading to an intercept |
| VIP | very important person |
| VIS | visibility |
| VLF | very low frequency (3 to 30 kHz) |
| VLR | very long range |
| VM | heading to a manual termination |
| VMC | visual meteorological conditions |
| VN* | chart of visibility and cloud layers |
| VNAV | vertical navigation (to be pronounced "VEE-NAV") |
| VOL | volume (followed by I, II...) |
| VOLMET | meteorological information for aircraft in flight |
| VOR | VHF omnidirectional radio range |
| VORTAC | VOR and TACAN combination |
| VOT | VOR airborne equipment test facility |
| VPA | vertical path angle |
| VPT | visual manoeuvre with prescribed track |
| VRB | variable |
| VSA | by visual reference to the ground |
| VSP | vertical speed |
| VTF | vector to final |
| VTOL | vertical take-off and landing |
| VV | vertical visibility (followed by figures in METAR/SPECI and TAF) |
| VWS* | vertical wind shear |
| W - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| W | west or western longitude |
| W | white |
| W | sea-surface temperature (followed by figures in METAR/SPECI) |
| W* | upper wind chart |
| WAAS | wide area augmentation system |
| WAC | world aeronautical chart ICAO 1:1 000 000 (followed by name/title) |
| WAFC | world area forecast centre |
| WB | westbound |
| WBAR | wing bar lights |
| WDI | wind direction indicator |
| WDSPR | widespread |
| WED | Wednesday |
| WEF | with effect from or effective from |
| WGS-84 | world geodetic system - 1984 |
| WI | within |
| WID | width or wide |
| WIE | with immediate effect or effective immediately |
| WILCO | will comply |
| WIND | wind |
| WIP | work in progress |
| WKN | weaken or weakening |
| WNW | west-north-west |
| WO | without |
| WPT | waypoint |
| WRNG | warning |
| WS | wind shear |
| WSPD | wind speed |
| WSW | west-south-west |
| WT | weight |
| WTC* | wake turbulence category |
| WTSPT | waterspout |
| WWW | world wide web |
| WX | weather |
| WXR | weather radar |
| X - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| X | cross |
| X* | FRA horizontal exit point |
| XBAR | crossbar (of approach lighting system) |
| XNG | crossing |
| XS | atmospherics |
| Y - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| Y | yellow |
| YCZ | yellow caution zone (runway lighting) |
| YES | yes (affirmative) (to be used in AFS as a procedure signal) |
| YR | your |
| Z - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| Z | co-ordinated universal time (in meteorological messages) |