Every major airport in the world has a three letter code. JFK, LHR, DXB, PEK. The International Air Transport Association assigns them, which is why they are called IATA codes. There are about ten thousand of them in active use. Here is why they look the way they look.

Why three letters

Three letters give 17,576 possible combinations. Airlines adopted two letter codes in the 1930s but ran out as aviation grew. The switch to three letters happened in the late 1930s, and the system has not needed another expansion since.

The naming patterns

Direct abbreviations

The simplest codes abbreviate the city or airport name.

  • LAX, Los Angeles.
  • DFW, Dallas Fort Worth.
  • MAD, Madrid.
  • KUL, Kuala Lumpur.

Historical codes

Some codes reflect the old name of an airport before it was renamed or expanded. These rarely change once set.

  • ORD, Chicago O'Hare. Named for Orchard Field, the airport's original name.
  • MCO, Orlando. Named for McCoy Air Force Base, from which the airport grew.
  • CDG, Paris Charles de Gaulle. The three initials of the namesake.

Letters added for uniqueness

Many US airports added an X to their two letter weather station code. That is why LA became LAX and Portland became PDX. Canadian airports followed a similar pattern with the letter Y at the start, which is why Toronto is YYZ and Vancouver is YVR.

Codes from local languages

Some codes make sense only if you know the local name.

  • NRT, Narita. Straightforward.
  • HND, Haneda. Also clear.
  • KIX, Kansai International. The X was added for uniqueness, K was taken.
  • CAN, Guangzhou Baiyun. Uses the old Canton name, not Guangzhou.
  • PEK, Beijing. Uses the old Peking transliteration.

Codes with odd stories

  • IAD, Washington Dulles. The code D U L would have been taken, so it was reversed to I A D.
  • EWR, Newark Liberty. NWR read too close to NWK, so they picked EWR.
  • MUC, Munich. Not M U N, that was taken by Matane in Canada.
  • SIN, Singapore Changi. The code is older than the city's independence.

What IATA does not code

IATA only codes airports relevant to commercial passenger service. Some military fields, private strips, and very small airports have no IATA code and use the four letter ICAO code instead. ICAO codes follow a different logic and are used for flight planning rather than passenger tickets.

How codes appear on your ticket

On a boarding pass or e-ticket itinerary, the three letter codes appear in bold, usually alongside the city name. The code is what the airline systems read, the city name is what the passenger reads. This is why sample itineraries from the Print A Trip builder always show both.

Try airport codes in the builder

Type a city or airport name in the search, the IATA code appears next to it.

Open the builder

Trivia worth knowing

  • Approximately ten thousand airports have IATA codes.
  • Approximately forty thousand airports have ICAO codes.
  • Codes are case insensitive in booking systems but always shown uppercase to users.
  • An airport can share a code with a city served by multiple airports. New York JFK, LGA, EWR all operate under the city code NYC in some systems.

For how the flight number attached to these airports is chosen, see how airlines assign flight numbers. For the six character PNR code that appears on the same document, read what is a PNR.