How Airports Are Given 3 Letter Codes

  •  Airport codes, whether three or four letters, are used to quickly reference an airport on various travel documents and for radio communication.
  •  IATA airport codes, established by the International Air Transport Association, are mostly based on the first three letters of the airport’s city and can be found on boarding passes and luggage tags.
  •  ICAO airport codes, defined by the International Civil Aviation Organization, are used by pilots and air traffic controllers and follow a different structure, with the start of the code denoting the country or region.

For most readers (who we assume love to fly), it’s relatively common knowledge that every airport has unique three and four-letter codes associated with it. On this article we will talk about both. The origin of the three-letter codes are known as IATA airport codes (since they are defined by the International Air Transport Association). The four-letter codes are defined by the International Civil Aviation Organization (ICAO).

From tickets to barcoded luggage tags to boarding passes, you’ll see these IATA-administered codes everywhere. On some flight tracking services, there might be a slightly different four-letter airport code. While pilots and industry-insiders know what the difference is, the knowledge isn’t common to everyone. Let’s jump into the world of airport codes and try to make some sense of it all.

What are airport codes at all?

Before we jump into three-letters vs. four-letters or IATA vs. ICAO, let’s take a step back and figure out why we need ‘codes’ in the first place. In essence, an airport code is a quick way to reference an airport – whether it’s on a boarding pass or a pilot’s flight plan, codes make life simpler. This is clearly useful when space is limited, such as the documents mentioned above.

If I had a flight to New Orleans, rather than spelling out “Louis Armstrong New Orleans International Airport” on a boarding pass, it’s the IATA-standard that the code MSY represents this destination. Likewise, a pilot’s flight plan will have the ICAO code of KMSY to represent the airport.

Codes can be useful for radio communication as well. Rather than trying to pronounce and communicate a difficult foreign airport name, a four-letter code can be transmitted instead. For example, if a pilot is flying to Moscow’s Sheremetyevo Alexander S. Pushkin International Airport, and needs to communicate it, then they can use the airport’s ICAO code: UUEE. Of course, over the radio, they would use the phonetic alphabet, saying: “Uniform-Uniform-Echo-Echo.”

To wrap up this explanation, airport codes are the language of airlines, aviators, and (many) travelers. Whether you use the IATA code or ICAO code depends on what you’re doing at the airport!

IATA airport codes (three letters)

First, let’s talk about IATA airport codes. IATA stands for the International Air Transport Association. It is a trade association that has established itself as the voice of representation for air travel as it pertains to the public and business.

As it is indeed a trade association, IATA’s policies aren’t legally binding. However, they have simply become accepted as the trade standard, thus making air travel easier and more streamlined. This is how ICAO defines IATA codes:

“IATA codes, also referred to as IATA location identifiers, are three-letter codes primarily used to identify airports but which can also refer to bus stations, ferry terminals, rail stations and helipads that are involved in intermodal travel. IATA airport codes are often based on the first three letters of the airport’s city. For example, ATL is the location identifier for the Hartsfield-Jackson Atlanta International Airport, and MEX is used for Mexico City. The airport codes can also refer to the city’s initials–HKG for Hong Kong or SLC for Salt Lake City.”

So every airport that has adopted this IATA standard has a three-letter code. So the next question will naturally be: “How are these codes determined?”

Well, to keep it simple, codes don’t really have any rule other than:

  • They have to be three letters
  • They must be unique and not in use by any other entity

Beyond this, everything is fair game. And we can clearly see this with the variety of IATA airport codes in the world. Let’s take a look at some examples and how the three letters are derived:

  • LHR and LGW: London Heathrow and London Gatwick
  • TPE: Taoyuan International Airport serves the city of Taipei (Taiwan)
  • NRT and HND: The two airports of Narita and Haneda both serve the Tokyo Metropolitan Area in Japan
  • DAR: Julius Nyerere International Airport serves the Tanzanian city of Dar es Salaam
  • KWI: Kuwait International Airport
  • BOG: El Dorado International Airport serves the city of Bogota (Colombia)

Sometimes airport codes are more associated with the airport’s name itself and aren’t tied to the name of the cities they serve. For example:

  • CDG: Paris Charles dGaulle
  • JFK: New York’s John FKennedy
  • SVO: Moscow’s Sheremetyevo International Airport

Then, as we explained in a previous article, Canadian airports have their own interesting pattern in which the overwhelming majority of airports in the country have IATA airport codes beginning with Y. The three-letter system allow us to have some fun as well. If you were traveling to OMG, you would be visiting Omega Airport in Namibia. If, by any chance, you are going from HEL to DIE, you know you would be departing from Helsinki and landing in Arrachart Airport in Madagascar (we know that’s unlikely to happen; in fact, it may have never happened in history, but it is fun to think about). There’s also LOL, WOW, YUM (ironically, not located in Canada), PEE, FUN, DOG, and so many more.

ICAO airport codes (four letters)

With air travel being one of the main ways we human travel between countries, it helps greatly to have an agreed-upon set of rules, policies, and procedures. This saves pilots and airline operations personnel a great deal of grief when planning a flight to a new country. This is the role that the International Civil Aviation Organization (ICAO) has.

The ICAO’s roots are founded in the Convention on International Civil Aviation (also known as Chicago Convention). This document was signed on 7 December 1944 by 52 States and ratified by an additional 26 states by 1947, which is when the ICAO officially came into being.