It doesn't matter if you are a pilot or a passenger, airport codes are there whenever you are flying: they are on passengers’ documents related to their reservations, flight tickets and luggage tags, and they are also used by air traffic controllers and pilots.
So you are certainly familiar with them, but have you ever wondered how those three, or four-letter acronyms are actually defined?
Airport codes are used to distinguish airports around the world, to ensure there is no confusion between countries and cities, and they are issued by the International Air Transport Association (IATA) and the International Civil Aviation Organization (ICAO).
IATA codes are 3-letter codes primarily used to identify airports but which can also refer to bus stations, ferry terminals, rail stations and helipads that are involved in intermodal travel. IATA airport codes are often based on the first 3 letters of the airport’s city or its initials. Here are some examples:
ATL (Hartsfield-Jackson International Airport, Atlanta, USA)
BOG (El Dorado International Airport, Bogotá, Colombia)
CDG (Charles de Gaulle Airport, Paris, France)
ICAO codes, on the other hand, are 4-letter codes used by pilots and air traffic controllers in their charts, on-board systems and in communications. They are also used to identify other aviation facilities, including weather stations, international flight service stations or area control centres.
The first letter in the ICAO code refers to a larger region where the airport is located. The second shows the country within that larger region, and the remaining two letters are a two-letter abbreviation. Some examples:
In Europe, codes begin with either an E (northern Europe,) B (Iceland and Kosovo), L (southern Europe). Barcelona’s Josep Tarradellas Barcelona-El Prat Airport’s ICAO code is LEBL– “L” denoting southern Europe, “E” for Spain (España) and finally “BL” for Barcelona.
Larger countries may have an initial letter dedicated to them, for example, Canadian airport codes start with “C.” Montreal/Pierre Elliot Trudeau International Airport would be CYUL–the “C” is for Canada, and “YUL” is the specific airport code.
Airport codes starting with “K” designate American airports – here there is a relationship between the ICAO and IATA codes since US airport ICAO codes are defined using “K” and then including the 3-letter IATA code, so New York’s John F. Kennedy International airport is “KJFK” since the IATA 3-letter code is just “JFK”.
Want to learn more?
ICAO’s Location Indicators (Doc 7910) contains listings of ICAO’s four-letter location indicators as well as the corresponding three-character IATA location identifier codes. A list of addresses of centres in charge of flight information regions (FIRs) and upper flight information regions (UIRs) is also included in the document.
You may also find IATA codes here: https://www.iata.org/en/publications/directories/code-search/