International Air Transport Association Airport Code - History and Conventions

History and Conventions

Airport codes arose out of the convenience that it 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, thus 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.

Generally speaking, airport codes are named after the first three letters of the city in which it is located - ATL for Atlanta, SIN for Singapore, MEX for Mexico City, IST for Istanbul; or a combination of the letters in its name, GDL for Guadalajara, JNB for Johannesburg, HKG for Hong Kong, and SLC for Salt Lake City. Some airports retained their NWS codes and simply appended an X at the end, such as LAX for Los Angeles, PDX for Portland, Oregon, and PHX for Phoenix.

There are many reasons for airport codes that do not fit the normal scheme described above. Some airports, for example, cross several municipalities or regions, and mix the letters around, giving rise to DFW for Dallas-Fort Worth, DTW for Detroit-Wayne, RDU for Raleigh-Durham, MSP for Minneapolis-St. Paul and LBA for Leeds Bradford (Airport).

Large metropolitan areas with more than one airport often resort to codes named after the airport itself instead of the city it serves. Often, another code is reserved which refers to the city itself. For instance:

• Tokyo (TYO) — Haneda (HND) and Narita (NRT)
• New York City (NYC) — John F. Kennedy International (JFK) and La Guardia (LGA)
• London (LON) — Heathrow (LHR) and Gatwick (LGW)
• Paris (PAR) — Orly (ORY) and Charles de Gaulle (CDG)
• São Paulo (SAO) — Congonhas (CGH) and Guarulhos (GRU)
• Seoul (SEL) — Incheon (ICN) Gimpo (GMP, formerly SEL)
• Rome (ROM) — Fiumicino (FCO) and Ciampino (CIA)
• Stockholm (STO) — Arlanda (ARN) and Bromma (BMA)
• Buenos Aires (BUE) — Ezeiza (EZE) and Aeroparque Jorge Newbery (AEP).
• Jakarta (JKT) — Soekarno-Hatta (CGK) is named after the district in which the airport is located, while the city also has another airport, Halim Perdanakusuma (HLP). JKT had referred to the city's former airport, Kemayoran Airport which is now closed.

Sometimes, a new airport is built, replacing the old one, leaving the city's new 'major' airport code to no longer correspond with the city's name. This is in conjunction to rules aimed to avoid confusion, 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 (formerly DIA), DCA for Reagan National (District of Columbia Airport), and BWI for Baltimore (Baltimore-Washington International). Since HOU is used for William P. Hobby Airport, the new Houston-Intercontinental became IAH. Shanghai-Hongqiao retained the code SHA, while the newer Pudong Airport adopted PVG. The opposite is true for Berlin, the former international airport Berlin-Tegel used the code TXL, while its smaller counterpart Berlin-Schönefeld used SXF; the new Berlin Brandenburg Airport has the code BER.

Since the US Navy reserved "N" codes and the Federal Communications Commission has reserved rights for "W" and "K", certain U.S. cities which begin with these letters had to adopt 'irregular' airport codes: EWR for Newark, ORF for Norfolk, Virginia, EYW for Key West, Florida, and APC for Napa, California. This 'rule' does not apply outside of the United States: Karachi is KHI, Warsaw is WAW, Nagoya is NGO. In addition, since "Q" was used for international communications, cities with "Q" beginning their name also had to find alternate codes, as in the case of Qiqihar (NDG) and Quetta (UET).

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 SPN, and some coincide with IATA codes of non-US airports.

Many cities who retain historical names in their airport codes despite the fact that their official name is now different. This is especially prominent in India: BOM for Mumbai (formerly Bombay), CCU for Kolkata (formerly Calcutta), and MAA for Chennai (formerly Madras); in China: CAN for Guangzhou (formerly Canton), PEK for Beijing (formerly Peking), and TAO for Qingdao (formerly Tsingtao). Similarly, this is the case with LED for St. Petersburg (formerly Leningrad), and SGN for Ho Chi Minh City (formerly Saigon).

Some airport codes are harder to explain, and each have their own peculiarities. In the United States, Chicago's O'Hare is assigned ORD, Nashville uses BNA, Knoxville uses TYS, and Kahului (main gateway into Maui) uses OGG. Orlando International Airport uses MCO, while Spokane International Airport goes by GEG. Most of these are named after individuals. In Asia, codes that do not correspond with their city's names include Niigata's KIJ, Nanchang's KHN, Zhengzhou's CGO, Pyongyang's FNJ, and Kobe's UKB.

Some airports are identified even in colloquial speech by their airport code. The most notable example is LAX.

All major airports in Canada use airport codes that begin with the letter "Y", although not all "Y" codes are Canadian. Many Canadian airports simply append a combinations of letters in the city's name to the "Y": YOW for Ottawa, YYC for Calgary, and YVR for Vancouver. Some Canadian codes are much harder to identify simply through the letters alone, particularly at two of Canada's largest airports, YUL for Montreal-Trudeau and YYZ for Toronto-Pearson.