In addition to individual-airport codes, IATA, the FAA, and various booking engines have assigned "metropolitan area codes" which represent several airports serving a metropolitan area. Not every region served with multiple airports is assigned a location identifier, however, nor are all IATA-recognized facilities necessarily included; furthermore, the inclusion or exclusion of a facility may depend on the booking system.
For example, the IATA: NYC code, representing the New York City area, includes flights to John F. Kennedy International Airport IATA: JFK, Newark Liberty International Airport IATA: EWR and LaGuardia Airport IATA: LGA. In some systems, Westchester County Airport IATA: HPN is also included; however, IATA: ZYP (New York Penn Station), IATA: ISP (Islip Airport), and IATA: JRA (West 30th Street Heliport) are generally not.
Metropolitan area airport codes are handy for simplifying flight searches into or out of a region. Some booking engines which include airports based on distance from a point can be tricked into extending the search through use of the city code.
Extra caution is advised when booking connecting flights, however, as the inbound leg may arrive at a different airport from the outbound leg, necessitating a ground transfer that may be costly or time-consuming. In particular, many major cities channel most international flights through one airport and most domestic or short-haul flights into a different one.
Smaller domestic airports are more likely to be served by low cost airlines but that might also force you to re-check your luggage. Ask your airline if they allow interlining tickets — checking your luggage through to the final destination on multiple tickets.
This is not a listing of all airport codes; this is a list of those special codes that cover multiple airports.
Metropolitan areas are organised alphabetically, first by continent then by city. Many flight search engines may not recognise all these group codes when making queries.
Seoul, South Korea IATA: SEL
Berlin, Germany IATA: BER Now only referring to Berlin Brandenburg Airport
Basel, Switzerland and Mulhouse, France: IATA: EAP - This is a special case as all codes refer to (separate areas of) the same airport, which is shared between France and Switzerland. Flights may be priced (and treated) differently depending on the airport code you book. All flights from France to MLH are treated as domestic flights, while flights from France to BSL are not. For search engines that can handle it, EAP should find quotes for both BSL and MLH
London, United Kingdom IATA: LON
Chicago, United States of America- IATA: CHI
Detroit, United States of America- IATA: DTT
Detroit Metro Wayne County IATA: DTW
Willow Run/Ypsilanti IATA: YIP
Houston, United States of America QHO - Recognized in Sabre and ITA but not IATA
Los Angeles, United States of America QLA - Recognized in Sabre and ITA but not IATA
Miami, United States of America QMI - Recognized in Sabre and ITA but not IATA
New York City, United States of America IATA: NYC
San Francisco Bay Area, United States of America QSF - Recognized in Sabre and ITA; elsewhere, IATA: QSF represents Ain Arnat Airport in Setif, Algeria
Washington DC, United States of America IATA: WAS
Buenos Aires, Argentina IATA: BUE
Rio de Janeiro, Brazil IATA: RIO