All around the world, airports use a three-letter code to get identified. Why ? Well you can imagine that it is a lot easier for airport logistic to write/read a three-letter code, rather than a whole airport name and its city.
When were they assigned?
In the 1930’s, aviation became pretty popular and to make it easier for pilots to locate where they were going, they started to use two-letter code from the National Weather Service to identify cities. However, not all cities have NWS, which is why a three-letter system for airports was implemented.
Why some codes easy and some other don’t make sense?
Most airport codes represent the first three letters of the city in which it is located. For example: ATL for Atlanta, LAS for Las Vegas, or SIN for Singapore. Some codes are also created from a combination of letters, such as HKG for Hong Kong, Other airports decided to keep their NWS code, and added an X at the end, which is why Los Angeles airport is LAX.
These previous codes are pretty easy to understand. However, why is Detroit called DTW? Well because is this case, like in other cases, they decided to cross several municipalities, or regions, and mixed the letters around. DTW stands for Detroit-Wayne County. Other codes also represent the name of the airport, rather than of the city where they are located, which is why Paris’ airport uses CDG, for Charles De Gaulle.
There is also a rule regulating codes for airports located whithin a 200 nautical miles area, stating that the “the first and second letters or second and third letters of an identifier may not be duplicated.”
Some airport codes are based on the airport’s previous name, for instance Chicago’s O’Hare’s code is ORD, standing for Orchard Field, while other codes can reflect a cities’ previous name, for example Beijing airport’s code is PEK, since the city was called Peking before.
In Canada, most airports use Y at the beginning of their three-letter codes. Many codes combine the Y with letters of the name of the city (YOW for Ottawa, YVR for Vancouver), but in some cases, the codes don’t have much significance. It is the case for Toronto-Pearson (YYZ).
Other codes have a historical meaning. Knoxville’s code is TYS since the land would have been donated by the Tyson family, to honor their son killed in World War I.
Wondering why Norfolk airport’s code is ORF, rather than NOR? Well this is because the US Navy reserved “N” codes. “W” and “K” were also reserved by the Federal Communications Commission, so cities starting with these letters had to adapt their airport codes. This also explains why Key West, Florida airport’s code is EYW. These ‘reserved’ letters are only in United States though.
Same rule also applies for cities starting with the letter “Q”, since this letter is used for international communications.
The letter ‘Z’ is also on the “reserved letters list”. It would be for special uses only. “Z” codes aren’t for physical airport, but could, for example, represent a command center that controls airline traffic.
We will conclude this article with an airport code that was the object of two requests (1998 & 2002) to the FAA to be changed: Sioux City’s Sioux Gateway Airport: “SUX”. Mayor Craig Berenstein has even described the code as embarrassing. The FAA ended up giving them alternatives, but at the end, airport managers decided to keep their original code, and in 2007, they embraced it and started to promote the airport with slogans such as “FLY SUX”.