How airport codes work (and why they don't match the city)
A three-letter IATA code identifies an airport for tickets, baggage and departure boards. Many are obvious (AMS for Amsterdam), but plenty are not (ORD for Chicago, MCO for Orlando). Here is how they are assigned and why they so often surprise you.
Who assigns airport codes?
The three-letter codes are managed by IATA, the International Air Transport Association. Every code is unique worldwide and, once assigned, tends to stay with the airport for good, even after the airport is renamed or rebuilt. A separate four-letter ICAO code is used by pilots and air traffic control; the two systems are explained in IATA vs ICAO.
Why don't airport codes match the city?
There are a few recurring reasons a code looks nothing like the place:
- The obvious code was already taken. Because every code is unique, an airport often cannot have the first three letters of its city, and picks something less predictable.
- The code comes from an older name. Many airports keep the code of the field, base or place they grew out of, long after a rename.
- Some first letters are reserved. In the United States, N is reserved for the Navy and W and K for radio call signs, so US airports avoid them. That is why Newark is EWR, not NEW.
- National conventions. Canada puts a Y in front of most of its airports (YYZ, YVR, YYC) for historical reasons.
Famous airport codes and where they come from
| Code | Airport | Where the code comes from |
|---|---|---|
| ORD | Chicago O'Hare | From its former name, Orchard Field (Orchard Place), before it was renamed after Edward O'Hare. |
| MCO | Orlando | From McCoy Air Force Base, the military field the airport grew out of. |
| MSY | New Orleans | From Moisant Stock Yards, the site named after aviator John Moisant. |
| YYZ | Toronto Pearson | Canada's airports use a Y prefix; YYZ comes from the old railway telegraph code for the area. |
| EWR | Newark | N is reserved for the US Navy, so Newark could not be NEW; it took letters from the middle and end instead. |
| LAX | Los Angeles | It was 'LA' when codes were two letters. When three letters became standard, an X was simply added. |
Frequently asked questions
Why is Chicago's airport code ORD?
ORD comes from Orchard Field, the airport's original name (it sat on Orchard Place). It was later renamed O'Hare, but the IATA code stayed ORD.
Why do Canadian airport codes start with Y?
Canada adopted a Y prefix for its airports for historical reasons tied to early railway and radio station codes. That is why you see YYZ (Toronto), YVR (Vancouver) and YYC (Calgary).
Why does Los Angeles use LAX?
Before the late 1940s many US airports used two-letter codes, so Los Angeles was 'LA'. When the industry moved to three-letter codes, LA simply gained an X, giving LAX. Phoenix (PHX) and Portland (PDX) did the same.
Can two airports have the same code?
No. Each IATA three-letter code is unique worldwide, which is exactly why an airport sometimes cannot use the obvious code for its city, and picks something less predictable instead.
Keep reading: What is an IATA code · IATA vs ICAO · ICAO code prefixes · all guides.