What Do Airline Two Letter Codes Stand For?

I recently shared the strange story of how Baltimore’s Friendship Airport (“BAL”) became BWI even though that code was already taken by Bewani, Papua New Guinea.

A lot of aviation codes have unique histories. Some of them are obvious. For instance United Airlines is UA, American Airlines is AA, and Delta is DL. Continental Airlines was CO and Northwest Airlines NW.

Southwest Airlines couldn’t have SW — that belonged to Seaborn World at the time (it’s now Air Namibia). So they took WN which approximates Western and ultimately works nicely because it can be said to stand for We’re Nuts! Although sadly Southwest no longer serves peanuts.

Lore is that Spirit Airlines’ NK stands for ‘Ned’s Kids’ after airline founder Ned Homfeld who had an especially close relationship with his employees. In fact I’m fairly sure that nickname came after the two letter code. On the other hand their ICAO code is ‘NKS’ which lends some support to the Ned’s Kids notion.

The Flight Detective tracks down the source for some less obvious two letter codes.

  • AY: Finnair is Aero Yhtiö or airline company.

  • BW: Caribbean Airlines dates to BWIA or British West Indies Airways.

  • EI: Aer Lingus’ code stands for Éire which means Ireland.

  • MS: EgyptAir began as Misr Airwork.

  • NH: Japan’s All Nippon Airways began as Nippon Helicopters.

  • OK: Czech Airlines uses this code, deriving from the radio call sign ‘OK’ assigned to then-Czechoslovakia in 1927.

  • RO: TAROM is the Romanian carrier or ‘RO’.

  • SN: Predecessor of Brussels Airlines was once Sabena.

  • SU: Aeroflot is ‘Soviet Union’. By the way Soviet Union diplomatic license plates in the US were ‘FC’ in the mid-1980s for “f- commies.” (Here’s that story.)

I’ve always thought Alaska Airlines (AS) should have been AK, but that’s now taken by AirAsia.

About Gary Leff

Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community InsideFlyer.com, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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  1. JetBlue=B6…. figure that out. I could almost see B7 since the upside down 7 looks like a J, and an upside down B still resembles a B. Any clues?

  2. As there is a limitation of two letter codes (less than 650) sometimes it is take it or leave it. New airlines apply for a code and are offered five or six choices. They choose what works for them from what is available. Traditionally ‘old’ codes are not reused for at least one year, to ensure no duplication in reservations systems, although this is no longer needed.

    LX came from Crossair – which was given SR’s international routes after their bankruptcy. There were originally two Thai airlines Thai International (TG) and the domestic airline (TH). When they merged they kept the international code. Singapore took whatever started with an ‘S’ when they were spun off from Malaysia Airways. NZ used to be TE (Tasman Empire) until they merged with New Zealand National Airways).

  3. I think some of the big three United States airline carriers with less then stellar customer service might want to see if they can change their IATA two letter code to “FU.” Previously, an airline named Air Littoral based at Méditerranée Airport, in Montpellier, France was assigned the FU designator before they ceased operations in February, 2004. Now, FU is assigned to Fuzhou Airlines located at Fuzhou, Fujian province, China. I look forward to seeing a flight from MAD to MIA being designated as FU69 instead of AA69.

  4. SW for Air Namibia actually was assigned because of their original name when they joined IATA, “South West Air Transport”–as Namibia was referred to as South West Africa prior to independence.

    I have never heard of Seaborn World, and can’t find any reference to that name in any airline history I have; not sure where that reference came from.

  5. Alaska Airlines used to be named Alaska Star Airlines, that’s where AS comes from.

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