Airports are often abbreviated by codes, including IATA codes and ICAO codes. Knowing them can be useful for orientation, booking or conversation
The International Air Transport Association defines a three-letter code for airports. These codes, which are intended to be globally unique, are used for ticketing, for booking flights and on baggage tags.
It is advisable to be aware of the code of the airport you are travelling to:
- Some large cities are served by more than one airport - either in the city itself or a suburb. London, for instance, is served by Heathrow Airport and a few alternates, such as Stansted.
- Some cities have identical names; Portland (Oregon) was named for Portland (Maine) but is on the opposite coast. Sydney (Nova Scotia) and Sydney (New South Wales) are as separate as night and day, or summer and winter, as they're half a world apart. You would not want to end up at the wrong Birmingham or Manchester.
- Some airports also have confusingly similar names, but serve different cities.The code is a useful confirmation that you have a ticket to the correct town, that the travel agent did not mishear Calgary (YYC IATA) as Cagliari (CAG IATA) for example. Or you are going to the correct San Salvador or Santa Rosa airport and to distinguish airports with the same or similar name, such as which Alexander the Great Airport (KVA IATA or SKP IATA)?
- To make the confusion complete, tiny Nogales is divided by the Arizona-Sonora border with a different single-runway Nogales International Airport serving general aviation on each side of the USA-México boundary.
Using the codes can make entering destinations on airline web sites quicker. On check-in, they're useful as a quick visual check that the luggage tag is sending your belongings to where you are travelling, or that the airline has not made a last minute change.
Many airports are known by their code and referenced by local public transport with them and thus the codes can be useful when communicating with taxi drivers. (To give just one example, the most convenient bus line to Tegel Airport in Berlin is line TXL.) They may also appear in diverse contexts as a colloquial nickname for the city which the airport serves.
In general, IATA assigns two-letter codes to airlines and three-letter codes to airports; three-letter codes for non-aviation facilities (such as rail stations with no associated airport) most often begin with Q, X or Z. Codes beginning with Y have for historical reasons mostly been assigned to Canadian airports.
ICAO codes are assigned by the International Civil Aviation Organization, a specialized agency of the United Nations. These four-letter codes are used by aviators for flight plans and navigation; they are separate and different from IATA codes, which are generally used by travel companies for airline timetables, reservations, and baggage tags. For example, the IATA code for London's Heathrow Airport is LHR and its ICAO code is EGLL. ICAO codes are commonly seen by passengers and the general public on flight-tracking services, though passengers will more often see the IATA codes, on their tickets and their luggage tags.
In general IATA codes are usually derived from the name of the airport or the city served, while ICAO codes are distributed by region and country. Far more aerodromes (in the broad sense) have ICAO codes than IATA codes, and to add to the confusion IATA codes (because of their use for ticketing) are sometimes assigned to railway stations. ZYP, for example, is Penn Station in New York City.
The first letters of the ICAO code identify a geographic region. Canada and the US Lower 48 mostly assign ICAO codes which match the same airport's IATA code, by adding a leading 'C' (Canada) or 'K' (USA 48). Elsewhere (including Hawaii) there is little correlation between IATA and ICAO tags. While IATA codes for any given airport rarely change and sometimes even preserve an anachronistic former name (PEK IATA for the main airport of Beijing for example), ICAO codes may and frequently do change when an airport comes under the control of a different country or government. For example, Berlin Schönefeld Airport remained SXF IATA but changed its ICAO code upon German reunification as it passed from the GDR to the Federal Republic of Germany.
As IATA is used by travel companies for ticketing and baggage handling, an airport with no scheduled flights may have an ICAO code but no IATA code. There's no corresponding IATA tag for KXTA, the ICAO airport code for Area 51 – a closely-guarded military test strip at Groom Lake, Nevada which is most emphatically not open to the voyager.
There are other identifiers in use; national rail carriers (such as Amtrak) have been known to assign their own non-standard codes to train stations on their own lines and agencies of national governments (such as the US Federal Aviation Administration or Transport Canada) will assign a numeric location identifier to even the tiniest private landing strip - even if there are no other facilities, no passenger terminal, no tickets and no IATA tags.