Short answer: an airport code is a three-letter identifier assigned by IATA, the International Air Transport Association, so that airlines, travel agents and baggage systems can name every airport without confusion. Most codes come from the city or airport name, but plenty come from old airfield names, weather station codes or whatever letters were still free. That is why Chicago is ORD, Los Angeles ends in X and Canada loves the letter Y.
IATA codes vs ICAO codes
There are two systems, and they do different jobs.
- IATA codes have three letters (LAX, JFK, LHR). They are the ones on your ticket, your boarding pass and the tag on your checked bag.
- ICAO codes have four letters and are used by pilots, air traffic control and flight plans. In the contiguous United States most are simply a K in front of the IATA code, so LAX becomes KLAX.
With three letters there are 17,576 possible combinations. That sounds like a lot until you remember how many airports, heliports and airstrips need one.
Why do some codes make no sense?
Because the code often remembers a history the city forgot:
- ORD (Chicago O'Hare) comes from Orchard Field, the airport's name before it was renamed after Butch O'Hare.
- MCO (Orlando) comes from McCoy Air Force Base, which shared the site.
- MSY (New Orleans) comes from Moisant Stock Yards, the land the airport was built on. New Orleans' older Lakefront Airport already had NEW.
- EWR (Newark) exists because the US Navy reserved codes starting with N, so Newark could not be NEW or NWK.
Why do LAX and PDX end in X?
Many early US airports used two-letter codes taken from National Weather Service stations. When the industry moved to three letters, some airports simply added an X: LA became LAX, PD became PDX. The X means nothing on its own, it just filled the gap.
Why do Canadian airports start with Y?
Most Canadian codes begin with Y (YYZ Toronto, YVR Vancouver, YUL Montreal). Canada added a Y to existing station codes to mark that an airport had a weather station, and the pattern stuck. It is also why our FUK→YOO design ends in Canada: YOO is Oshawa Executive Airport in Ontario.
City codes vs airport codes
Big cities with several airports also get a metropolitan code. NYC covers JFK, LaGuardia (LGA) and Newark (EWR). LON covers Heathrow (LHR), Gatwick (LGW) and more. Searching a city code shows flights from every airport in that area. Three of those airports are on our Real Routes tees: JFK→LAX, JFK→LHR and LGA→ORD, some of the busiest routes Americans fly.
Can an airport change its code?
Rarely. Codes are baked into decades of airline systems, so IATA only reassigns one when there is a strong reason. That is why Sioux City, Iowa still flies as SUX, and why accidental words like LOL, FUN and PIE are here to stay. The dictionary words are all in airport codes that spell words (753 of them), and the texting ones like LOL in internet slang words that are real airport codes. For a spooky version, see Halloween airport codes (BOO is Bodø, Norway). And for the office, see job titles that are airport codes (CEO is in Angola).
Quick FAQ
Who assigns airport codes?
IATA assigns three-letter codes under its Resolution 763, administered from its headquarters in Montreal. ICAO codes are managed through national aviation authorities.
Are airport codes unique?
Yes. Each three-letter IATA location code points to one place, which is exactly why they are useful on bag tags.
What is the funniest real airport code?
Our vote goes to SUX (Sioux City, Iowa), with LOL (Lovelock, Nevada) close behind. Put them together and you get LOL→SUX.
Every I OFTEN FLY design is built from two real codes that spell something when you read them together. Browse the airport code t-shirts, aviation hoodies and airport code hats, or find a present in our aviation gifts.