Continuing the discussion from Trolls R Us Resurrections:
I was going to post this in the above-mentioned Pit thread where there was some discussion of three-letter IATA airport codes, but it seemed like an excessive hijack even for the Pit. This subject has been discussed before but this is a bit more detail.
Some random trivia, because airport codes interest me … so this is offered for those who have an affinity for completely useless information …
ORD may not immediately evoke Chicago but it’s a major hub so its airport code is generally familiar. I used to think the code came from the name O’Hare Field, but as someone correctly pointed out earlier, when the IATA code was first assigned in the 1940s it was still called Orchard Field.
In the US and around the world, most (not all) IATA codes have some mnemonic significance. When it has no similarity to the city name it’s often derived from the airport name, as in ORD for Chicago, LHR for London Heathrow, or CDG for Paris (Charles DeGualle airport). Sometimes it gets mangled by restrictions, like the US Navy trying (not altogether successfully) to get dibs on all codes starting with “N”, hence Newark becoming EWR. Other times the codes reflect city combinations – DFW for Dallas-Ft. Worth, MSP for Minneapolis St. Paul.
The similarity to city names or well-known airport names makes the use of airport codes fairly natural especially to seasoned travelers, as in “I’m flying from ATL to LAX”. “LAX” is probably the most recognizable airport code in the world. It’s a little different in Canada, though. It’s hard to say “I’m flying from YYZ to YUL” without sounding like you’re describing an interplanetary voyage in a galaxy far, far away.
The way these codes came about goes back to the 1920s and 30s. Canada has since standardized on “Y” as the first letter of all airport codes, although a few smaller ones start with “Z”. Originally, though, the story goes that old two-letter airport codes back in the day were preceded by “Y” (“Yes”) if the airport had a weather station, which usually also meant a radio beacon. If not, the code was preceded by “W” (“Without”). The “W” codes have since fallen out of use.
As for the other two letters, I haven’t positively been able to confirm this mystery but it seems that they were usually sourced from the original two-letter codes of either the airport weather station and/or nearby railway stations. Thus “YZ” was the code for the Malton station, near which Pearson International Airport was built, and now bears the IATA code YYZ. A few airports have semi-mnemonic codes (Vancouver is YVR) but most do not.
To add to the fun, YUM is not in Canada at all but refers to Yuma, Arizona; YVA is Moroni, the capital of Comoros off the east coast of Africa, and YVD is Yeva in Papua New Guinea. Bastards stole our codes!