IATA airport code
An IATA airport code, also known as an IATA location identifier, IATA station code, or simply a location identifier,  is a three-letter geocode designating many airports and metropolitan areas around the world, defined by the International Air Transport Association (IATA). The characters prominently displayed on baggage tags attached at airport check-in desks are an example of a way these codes are used.
The assignment of these codes is governed by IATA Resolution 763, and it is administered by the IATA's headquarters in Montreal. The codes are published semi-annually in the IATA Airline Coding Directory. 
IATA also provides codes for railway stations and for airport handling entities. A list of airports sorted by IATA code is available. A list of railway station codes, shared in agreements between airlines and rail lines such as Amtrak, SNCF French Railways, and Deutsche Bahn, is available. Many railway administrations have their own list of codes for their stations, such as the list of Amtrak station codes.
- See also: List of airports by IATA and ICAO code
Airport codes arose out of the convenience that the practice brought pilots for location identification in the 1930s. Initially, pilots in the United States used the two-letter code from the National Weather Service (NWS) for identifying cities. This system became unmanageable for cities and towns without an NWS identifier, and the use of two letters allowed only a few hundred combinations; a three-letter system of airport codes was implemented. This system allowed for 17,576 permutations, assuming all letters can be used in conjunction with each other. 
Predominantly, airport codes are named after the first three letters of the city in which it is located— ATL for Atlanta, SIN for Singapore, ASU for Asunción, MEX for Mexico City, DEN for Denver; IST for Istanbul; or a combination of the letters in its name, ALA for Almaty (formerly known as Alma-Ata), EWR for Newark, GDL for Guadalajara, JNB for Johannesburg, HKG for Hong Kong, SLC for Salt Lake City and WAW for Warsaw. Some airports in the United States retained their NWS codes and simply appended an X at the end, such as LAX for Los Angeles, PDX for Portland, and PHX for Phoenix. 
Sometimes the airport code reflects pronunciation, rather than spelling, such as NAN, which reflects the pronunciation of "Nadi" as [ˈnandi] in Fijian, where "d" is realized as the prenasalized stop [ⁿd].
For many reasons, some airport codes do not fit the normal scheme described above. Some airports, for example, cross several municipalities or regions, and therefore, use codes derived from some of their letters, resulting in DFW for D allas/Fort Worth, DTW for D etroit–Wayne County, LBA for L eeds–Bradford (Airport), MSP for M inneapolis–Saint Paul, and RDU for R aleigh–DUrham. Other airports—particularly those serving cities with multiple airports—have codes derived from the name of the airport itself, such as JFK for New York's John F. Kennedy or CDG for Paris' Charles de Gaulle (see below). In some cases, the code comes from the airport's unofficial name, such as Kahului Airport's OGG (for local aviation pioneer Jimmy Hogg).
Canada's unusual codes–which bear little to no similarity with any conventional abbreviation to the city's name–such as YUL in Montréal, and YEG in Edmonton, originated from the two-letter codes used to identify weather reporting stations in the 1930s. The letters preceding the two-letter code follow the following format:
- Y (meaning "yes") if the reporting station was co-located with an airport.
- W (meaning "without") if the reporting station was not co-located with an airport.
- U if the reporting station was co-located with a non-directional beacon.
- X if the last two letters of the code had already been taken by another Canadian airport.
- Z if the resulting code had already been taken by a US airport.
In large metropolitan areas, airport codes are often named after the airport itself instead of the city it serves, while another code is reserved which refers to the city itself. For instance:
- Beijing (BJS) – Capital (PEK) and Daxing (PKX).
- Berlin (BER) – Tegel (TXL) and Schönefeld (SXF), and the under construction Berlin Brandenburg Airport (BER). The city also previously had another airport, Tempelhof (THF), which is now closed.
- Bucharest (BUH) – Otopeni (OTP) is named after the town of Otopeni where the airport is located, while the city also has a business airport inside the city limits named Băneasa (BBU).
- Buenos Aires (BUE) – Ezeiza (EZE) is named after the suburb in Ezeiza Partido where the airport is located, while Aeroparque Jorge Newbery (AEP) is in the city proper.
- Chicago (CHI) – O'Hare (ORD), named after Orchard Field, the airport's former name, Midway (MDW), and Rockford (RFD)
- Jakarta (JKT) – Soekarno–Hatta (CGK) is named after Cengkareng, the district in which the airport is located, while the city also has another airport, Halim Perdanakusuma (HLP). JKT used to refer to the city's former airport, Kemayoran Airport, which closed down in the mid-1980s.
- London (LON) – Heathrow (LHR), Gatwick (LGW), City (LCY),  Stansted (STN), Luton (LTN) and Southend (SEN)
- Milan (MIL) – Malpensa (MXP), Linate (LIN) and Orio al Serio (BGY)
- Montreal (YMQ) – Trudeau (YUL), Mirabel (YMX), and Saint-Hubert (YHU)
- Moscow (MOW) – Sheremetyevo (SVO), Domodedovo (DME), Vnukovo (VKO), Ostafyevo (OSF), Zhukovsky (ZIA)
- New York City (NYC) – John F. Kennedy (JFK, formerly Idlewild (IDL)), LaGuardia (LGA), and Newark (EWR)
- Osaka (OSA) – Itami (ITM, formerly OSA), Kansai (KIX), and Kobe (UKB)
- Paris (PAR) – Orly (ORY), Charles de Gaulle (CDG), Le Bourget (LBG) and Beauvais (BVA)
- Rio de Janeiro (RIO) – Galeão (GIG) and Santos Dumont (SDU)
- Rome (ROM) – Fiumicino (FCO) and Ciampino (CIA)
- São Paulo (SAO) – Congonhas (CGH), Guarulhos (GRU) and Campinas (VCP)
- Sapporo (SPK) – Chitose (CTS) and Okadama (OKD)
- Seoul (SEL) – Incheon (ICN) and Gimpo (GMP, formerly SEL)
- Stockholm (STO) – Arlanda (ARN), Bromma (BMA), Nyköping–Skavsta (NYO) and Västerås (VST)
- Tenerife (TCI) – Tenerife North (TFN) and Tenerife South (TFS)
- Tokyo (TYO) – Haneda (HND, formerly TYO) and Narita (NRT)
- Toronto (YTO) – Pearson (YYZ), Bishop (YTZ), Hamilton (YHM), and Waterloo (YKF)
- Washington, D.C. (WAS) – Dulles (IAD), Reagan (DCA), and Baltimore–Washington (BWI)
Or using a code for the city in one of the major airports and then assigning another code to another airport:
- Almaty (ALA) – Self-named (ALA) and Burundai (BXJ)
- Bangkok (BKK) – Suvarnabhumi (BKK) and Don Mueang (DMK, formerly BKK)
- Belfast (BFS) – Self-named (BFS) and George Best (BHD)
- Colombo (CMB) – Bandaranaike (CMB) and Ratmalana (RML)
- Dakar (DKR) – Senghor (DKR) and Diass (DSS)
- Dallas–Fort Worth (DFW) – Self-named (DFW), Love Field (DAL), Meacham (FTW), Alliance (AFW), Addison (ADS)
- Dubai (DXB) – International (DXB) and Al Maktoum (DWC)
- Glasgow (GLA) – International (GLA) and Prestwick (PIK)
- Houston (HOU) - Hobby (HOU) and Intercontinental (IAH)
- Istanbul (IST) – Self-named (IST), Sabiha Gökçen (SAW) and Atatürk (ISL, formerly IST)
- Johannesburg (JNB) – O. R. Tambo (formerly Jan Smuts) (JNB) and Lanseria (HLA)
- Kuala Lumpur (KUL) – Sepang (KUL) and Subang (SZB, formerly KUL)
- Kyiv (IEV) – Zhuliany (IEV) and Boryspil (KBP)
- Los Angeles (LAX) – Self-named (LAX), Ontario (ONT), Orange County (SNA), Van Nuys (VNY), Palmdale (PMD), Long Beach (LGB) and Burbank (BUR)
- Medellín (MDE) – José María Córdova (MDE) and Olaya Herrera (EOH)
- Melbourne (MEL) - Tullamarine (MEL), Essendon (MEB) and Avalon (AVV)
- Miami (MIA) – Self-named (MIA), Fort Lauderdale (FLL), West Palm Beach (PBI)
- Nagoya (NGO) – Centrair (NGO) and Komaki (NKM, formerly NGO)
- San Francisco (SFO) – Self-named (SFO), Oakland (OAK), San Jose–Mineta (SJC), Sonoma–Schulz (STS)
- Seattle (SEA) – Tacoma (Sea–Tac) (SEA) and Paine Field (PAE)
- Shanghai (SHA) – Pudong (PVG) and Hongqiao (SHA)
- Sydney (SYD) – Kingsford Smith (SYD) and Nancy-Bird Walton (SWZ)
- Taipei (TPE) – Taoyuan (formerly Chiang Kai-shek) (TPE) and Songshan (TSA, formerly TPE)
- Tehran (THR) – Imam Khomeini (IKA) and Mehrabad (THR)
When different cities with the same name each have an airport, they need to be assigned different codes. These are some examples:
- Birmingham–Shuttlesworth International Airport (BHM) is in Birmingham, Alabama, the United States and Birmingham Airport (BHX) is in Birmingham, England, United Kingdom.
- Norman Y. Mineta San Jose International Airport (SJC) is in San Jose, California, the United States and Juan Santamaría International Airport (SJO) is in San José, Costa Rica.
- Portland International Jetport (PWM) is in Portland, Maine, while Portland International Airport (PDX) is in Portland, Oregon.
- Manchester Airport (MAN) is in Manchester, England, United Kingdom, while Manchester-Boston Regional Airport (MHT) is in Manchester, New Hampshire, United States.
Sometimes, a new airport is built, replacing the old one, leaving the city's new "major" airport (or the only remaining airport) code to no longer correspond with the city's name. The original airport in Nashville, Tennessee was built in 1936 as part of the Works Progress Administration and called Berry Field with the designation, BNA. A new facility known as Nashville International Airport was built in 1987 but still uses BNA. This is in conjunction to rules aimed to avoid confusion that seem to apply in the United States, which state that "the first and second letters or second and third letters of an identifier may not be duplicated with less than 200 nautical miles separation."  Thus, Washington D.C. area's three airports all have radically different codes: IAD for Washington–Dulles, DCA for Washington–Reagan (District of Columbia Airport), and BWI for Baltimore (Baltimore–Washington International, formerly BAL).  Since HOU is used for William P. Hobby Airport, the new Houston–Intercontinental became IAH.  The code BKK was originally assigned to Bangkok–Don Mueang and was later transferred to Suvarnabhumi Airport, while the former adopted DMK. The code ISK was originally assigned to Gandhinagar Airport (Nashik's old airport) and later on transferred to Ozar Airport (Nashik's current airport). Shanghai–Hongqiao retained the code SHA, while the newer Shanghai–Pudong adopted PVG. The opposite is true for Berlin: the airport Berlin–Tegel uses the code TXL, while its smaller counterpart Berlin–Schönefeld uses SXF; the yet-to-open Berlin Brandenburg Airport has the airport code BER, which is also part of its branding. The airports of Hamburg (HAM) and Hannover (HAJ) are less than 100 nautical miles (190 km) apart and therefore share the same first and middle letters, indicating that this rule might be followed only in Germany.
Many cities retain historical names in their airport codes, even after having undergone an official name/spelling/transliteration change:
- in Armenia: LWN for Gyumri (formerly Leninakan)
- in Bangladesh: DAC for Dhaka (formerly Dacca)
- in Canada: YFB for Iqaluit (formerly Frobisher Bay)
- in China: PEK for Beijing (formerly Peking), TSN for Tianjin (formerly Tientsin), CKG for Chongqing (formerly Chungking), NKG for Nanjing (formerly Nanking), TAO for Qingdao (formerly Tsingtao), CTU for Chengdu (formerly Chengtu), and CAN for Guangzhou (formerly Canton). The older IATA codes follow Chinese postal romanization, introduced in 1906, officially abolished in 1964 and in use well into the 1980s, while gradually superseded by Pinyin
- in Greenland: most airports, including SFJ for Kangerlussuaq (formerly Søndre Strømfjord) and GOH for Nuuk (formerly Godthåb)
- in India: BOM for Mumbai (formerly Bombay), CCU for Kolkata (formerly Calcutta), and MAA for Chennai (formerly Madras)
- in Indonesia: TKG for Bandar Lampung (formerly Tanjung Karang), UPG for Makassar (formerly Ujung Pandang). In addition, when the Enhanced Indonesian Spelling System was introduced in 1972, a few older IATA codes retained the previous spelling: BTJ for Banda Aceh (formerly Banda Atjeh), DJJ for Jayapura (formerly Djajapura), JOG for Yogyakarta (formerly Jogjakarta)
- in Kazakhstan: NQZ for Nur-Sultan (formerly Astana and Tselinograd (TSE), SCO for Aktau (formerly Shevchenko), GUW for Atyrau (formerly Guryev), KOV for Kokshetau (formerly Kokchetav), DMB for Taraz (formerly Dzhambyl), PLX for Semey (formerly Semipalatinsk)
- in Kyrgyzstan: FRU for Bishkek (formerly Frunze)
- in Moldova: KIV for Chișinău (formerly Kishinev)
- in Montenegro: TGD for Podgorica (formerly Titograd)
- in Myanmar: RGN for Yangon (formerly Rangoon)
- in Pakistan: LYP for Faisalabad when the city changed its name from Lyallpur to Faisalabad in honour of the King Faisal of Saudi Arabia.
- in Russia: LED for St. Petersburg (formerly Leningrad), GOJ for Nizhny Novgorod (formerly Gorky), SVX for Yekaterinburg (formerly Sverdlovsk), KUF for Samara (formerly Kuybyshev), OGZ for Vladikavkaz (formerly Ordzhonikidze) and others
- in South Africa: NLP for Mbombela (formerly Nelspruit) and PTG for Polokwane (formerly Pietersburg)
- in Tajikistan: LBD for Khujand (formerly Leninabad)
- in Turkmenistan: KRW for Türkmenbaşy (formerly Krasnovodsk); CRZ for Türkmenabat (formerly Chardzhev)
- in Ukraine: IEV for Kyiv; VSG for Luhansk (formerly Voroshilovgrad); KGO for Kropyvnytskyi (formerly Kirovograd); LWO for Lviv (formerly Lwów while part of Poland until 1939, and still called Lvov in Russian); IFO for Ivano-Frankivsk (in Soviet times spelt in Russian as Ivano-Frankovsk);
- in Vietnam: SGN for Ho Chi Minh City (formerly Saigon)
Some airport codes are based on previous names associated with a present airport, often with a military heritage. These include:
- Chicago's O'Hare, which is assigned ORD based on its old name of Orchard Field. It was expanded and renamed O'Hare in the mid-1950s.
- Fresno Yosemite International Airport uses the code FAT, derived from a previous name of the airport, Fresno Air Terminal.
- Orlando International Airport was founded as Orlando Army Air Field #2 but uses MCO for having been renamed McCoy Air Force Base in 1959 in honor of a wing commander who crashed at the field in 1958. It was converted in the early 1960s to joint civilian/military use and renamed Orlando Jetport at McCoy, then renamed Orlando International Airport in the early 1980s.
- Spokane International Airport was so named in 1960 but goes by GEG because it was built on the former Geiger Field, renamed in 1941 for Major Harold Geiger when the US Army acquired it.
Other airport codes are inconspicuous in origin, and each has its own peculiarities:
- Nashville uses BNA for its former name as Berry Field, henceforth Berry Nashville Airport
- Louisville Muhammad Ali International Airport is SDF for Standiford Field, its original name.
- Knoxville uses TYS for Charles McGhee Tyson, whose family donated the land for the first airport in Knoxville
- Kahului, the main gateway into Maui, uses OGG in homage to Hawaiian aviation pioneer Bertram J. Hogg
- Gold Coast, Australia uses OOL due to its former name as Coolangatta Airport, named after the suburb in which it is located
- Sunshine Coast, Australia uses MCY due to its former names Maroochydore Airport and Maroochydore-Sunshine Coast Airport. It is actually located in Marcoola rather than Maroochydore
EuroAirport Basel Mulhouse Freiburg, which serves three countries, has three airport codes: BSL, MLH, EAP
Some European cities have a different name in their respective language than in English, yet the airport code represents only the English name. Examples include:
- CGN - Cologne/Köln (Germany)
- CPH - Copenhagen/København (Denmark)
- FLR - Florence/Firenze (Italy)
- GVA - Geneva/Genève (Switzerland)
- OPO - Oporto/Porto (Portugal)
- PRG - Prague/Praha (Czechia)
- VCE - Venice/Venezia (Italy)
- VIE - Vienna/Wien (Austria)
Some airports are identified even in the colloquial speech by their airport code. The most notable examples are LAX and JFK.[ citation needed]
Since the U.S. Navy reserved "N" codes and to prevent confusion with Federal Communications Commission broadcast call signs beginning with "W" and "K", certain U.S. cities which begin with these letters had to adopt "irregular" airport codes when their airports opened: EWR for Newark, ORF for Norfolk, Virginia, EYW for Key West, Florida, OME for Nome and APC for Napa, California.  This practice is not followed outside the United States: Karachi is KHI, Warsaw is WAW, and Nagoya is NGO. In addition, since three letter codes starting with Q are widely used in radio communication, cities with "Q" beginning their name also had to find alternate codes, as in the case of Qiqihar (NDG), Quetta (UET), Quito (UIO), and Quimper (UIP).[ citation needed]
IATA codes should not be confused with the FAA identifiers of US airports. Most FAA identifiers agree with the corresponding IATA codes, but some do not, such as Saipan whose FAA identifier is GSN and its IATA code is SPN, and some coincide with IATA codes of non-US airports.[ citation needed]
Most large airports in Canada have codes that begin with the letter "Y", although not all "Y" codes are Canadian (for example, YUM for Yuma, Arizona and YNT for Yantai, China) and not all Canadian airports start with the letter "Y" (for example ZBF for Bathurst, New Brunswick). Many Canadian airports have a code that starts with W, X or Z, but none of these are major airports. When the Canadian transcontinental railways were built, each station was assigned its own two-letter Morse code. VR stands for Vancouver, TZ Toronto, QB Quebec, WG Winnipeg, SJ Saint John, YC Calgary, OW Ottawa, EG Edmonton, etc. When the Canadian government established airports, it used the existing railway codes for them as well. If the airport had a weather station, authorities added a "Y" to the front of the code, meaning "Yes" to indicate it had a weather station or some other letter to indicate it did not. When international codes were created in cooperation with the United States, because "Y" was seldom used in the US, Canada simply used the weather station codes for its airports, changing the "Y" to a "Z" if it conflicted with an airport code already in use. The result is that most major Canadian airport codes start with "Y" followed by two letters in the city's name: YOW for Ottawa, YWG for Winnipeg, YYC for Calgary, and YVR for Vancouver, whereas other Canadian airports append the two-letter code of the radio beacons that were the closest to the actual airport, such as YQX in Gander and YXS in Prince George.
Four of the ten provincial capital airports in Canada have ended up with codes beginning with YY, including YYZ for Toronto, Ontario, YYJ for Victoria, British Columbia, YYT for St. John's, Newfoundland, and YYG for Charlottetown, Prince Edward Island. Canada's largest airport is YYZ for Toronto–Pearson (YTZ was used for Toronto City Airport, so YYZ is the station code for a village called Malton, which is where Toronto Pearson International Airport is actually located). YUL is used for Montréal–Trudeau (UL was the ID code for beacon in the city of Kirkland, now the location of Montréal–Trudeau). While these codes make it difficult for the public to associate them with a particular Canadian city, some codes have become popular in usage despite their cryptic nature, particularly at the largest airports. Toronto's code has entered pop culture in the form of "YYZ", a song by the rock band Rush which utilizes the Morse code signal as a musical motif. Some airports have started using their IATA codes as marketing brands. Calgary International Airport has begun using its airport code YYC as a marketing brand and name for the airport authority web site (yyc.com),  while Vancouver International Airport advertises as YVR (yvr.com).
Numerous New Zealand airports use codes which contain a letter Z, to distinguish them from similar airport names in other countries. Examples include HLZ for Hamilton, ZQN for Queenstown, and WSZ for Westport.
There are several airports with scheduled service that have not been assigned ICAO codes that do have IATA codes. For example, several airports in Alaska have scheduled commercial service, such as Stebbins and Nanwalek, which use FAA codes instead. There are also airports with scheduled service for which there are ICAO codes but not IATA codes, such as Nkhotakota Airport/Tangole Airport in Malawi or Chōfu Airport in Tokyo, Japan. There are also several minor airports in Russia (e.g. Omsukchan Airport) which instead use internal Russian codes for booking. Flights to these airports cannot be booked through the international air booking systems or have luggage transferred to there, and thus, they are booked instead through the airline or a domestic booking system. Thus, neither system completely includes all airports with scheduled service.
- Airline codes
- Airspace class
- Computer network naming scheme, another possible use of IATA airport codes
- ICAO airport code
- International Air Transport Association code
- IATA. "IATA - Codes - Airline and Airport Codes Search". www.iata.org. Archived from the original on 2008-10-13. Retrieved 2009-09-22.
- IATA. "IATA - Airline Coding Directory". www.iata.org.
- "Airport ABCs: An Explanation of Airport Identifier Codes". Air Line Pilot. Air Line Pilots Association. 1994. Retrieved 6 January 2012.
- "YYC: Calgary Airport Authority". Retrieved 22 March 2015.
|Wikivoyage has a travel guide for Metropolitan area airport codes.|
- IATA official web site
- IATA Airline and Airport Code Search
- United Nations Code for Trade and Transport Locations (UN/LOCODE) – includes IATA codes
- "Airport ABCs: An Explanation of Airport Identifier Codes". Air Line Pilot. Air Line Pilots Association. December 1994.
- Airport IATA/ICAO Designator / Code Database Search (from Aviation Codes Central Web Site – regular updates)
- OpenFlights, a freely licensed ( ODbL) aviation data set