Airline Abbreviations – Why there are three letter codes

airline code abbreviations on Ahoy

LAX? MUC? DXB? Ever wondered where the three letter abbreviations came from and why they don’t always make sense to the city in question?

airline code abbreviations on Ahoy

You know these three letter codes like the back of your hand when you travel frequently. But, ever questioned where they came from…why sometimes they don’t quite relate to the actual destination in an obvious way?

In the early 1900s, when there wasn’t much of a high demand for air travel a two letter coding system was put in place by weather stations to track data from cities. As air travel began to grow early airlines just copied this system, however when things started to explode in the 1930’s some towns without any codes needed an identifier.

The three-letter system was then born, to give a large number of possibilities that would cover the range of cities that had no code. Those airports that already had a weather station code simply were given an X after them to make the transition seamless; therefore this is why Los Angeles became LAX in 1947, Portland became PDX and Phoneix became PHX.

LAX airport view from above

As air travel continued to grow, it became apparent this three-letter abbreviation system didn’t give enough possibilities to cover all of the cities and airports that were continually popping up. Hence why now there are some codes which have very arbitrary meaning.

These could be a combination of letters that relate to the airports rather than the city, inverting some letters, using the middle of the city name rather than letters at the start or end, or even using local popular areas as the identifier.

Here are some of the fun ones for those of you who like trivia!


Knoxville in Tenessee got this seemingly unrelated tag from the Tyson family, who donated the land in honour of their son who was killed in World War I.


Orlando International Airport, is coded as MCO, because it was built on the land which used to be the McCoy Airforce Base.


Dulles International Airport in Washington D.C., used to be coded as DIA. However, when written it was often misread as DCA – a different Washington airport. Therefore it was reversed to IAD to avoid any confusion and planes heading to the incorrect airport.


Kahului Airport in Hawaii honours Hawaiian-born pilot Bertram J. Hogg.


O’hare International Airport in Chicago is coded by the original name for it’s airport, which was Orchard Field Airport. Later it was renamed after the Medal of Honor recipient Edward O’Hare, yet the code remained the same.


We’d love to hear any more fun trivia you have on airport codes and the origin of their abbreviations! Comment below so we can add to our list. Don’t forget to check out Ahoy for all your frequent travel needs.