Explaining Three Letter Airport Codes

Q: I’m intrigued by the three-letter codes for airports. Where do they come from? Many seem to make no sense (MCO for Orlando?).

The three-letter abbreviations you speak of are IATA abbreviations (see intro). There also are 4-letter abbreviations devised by ICAO (International Civil Aviation Organization), which is a branch of the United Nations, but these are used only for navigation and technical purposes.

Many of the seemingly arbitrary ones are carry-overs from former names for the airport. MCO is derived from McCoy Field, the original name for Orlando International. O’Hare’s identifier, ORD, pays tribute to the old Orchard Field. Or they can be geographical associations, some more obscure than others: In Rio de Janeiro your plane will land at Galeao, on Governor’s Island (Ilha do Governador), lending to the code GIG.

Other examples are fairly intuitive, such as LHR (London Heathrow) or KIX (Osaka, Kansai International), while a few are completely mysterious. Can anyone tell me why Maui uses OGG?

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This Q&A is part of a collection that originally appeared on Salon.com. Patrick Smith, 38, is an erstwhile airline pilot, retired punk rocker and air travel columnist. His book, Ask the Pilot (Riverhead) was voted “Best Travel Book of 2004” by Amazon.com. Patrick has traveled to more than 55 countries and always asks for a window seat. He lives near Boston.