Summary

• The three-letter airport codes are designated by IATA, while the four-letter codes are designated by ICAO.
• In the United States, most ICAO codes are the same as their IATA codes with the prefix 'K'.
• Hawaii and Alaska use the 'P' prefix for their ICAO codes, and each country, state, or region using the 'P' prefix is assigned a second letter.

Have you ever wondered why all airports have a three-letter code, such as LAX for Los Angeles Airport or JFK for New York-JFK Airport? Passengers commonly notice the three letters on their airline tickets, boarding passes, and luggage tags. The three-letter code, known as the airport identifier, are codes designated by the International Air Transport Association (IATA).

On the other hand, the International Civil Aviation Organization (ICAO) also designates airports with a four-letter code, identifying airports and landing strips. The additional letter generally consists of a country or a region prefix. This article delves deeper into the meaning of these codes and how all airports in the United States have the letter "K" in the prefixes, as described by ICAO and IATA.

ICAO Airport Codes

In the United States, the ICAO codes of most airports are simply their IATA code (think 'ORD' or 'MIA') with the prefix 'K' ('KORD' or KMIA'). The International Civil Aviation Organization (ICAO) assigned the prefix' K' to the United States, as it wanted these prefixes to reflect the geographical location of each airport or airstrip. Other prefixes include:

• 'E' for Northern Europe, including the United Kingdom, Scandinavia, Germany, and Poland
• 'O' for the Middle East, including Saudi Arabia, Iran, Yemen and Oman
• 'Z' for Continental East Asia, including China and Mongolia
• 'S' for South America, including Brazil, Argentina and Venezuela
• 'U' for former Soviet Republics, including Russia, Georgia and Kazakhstan

The below image highlights how ICAO prefixes depend on the geographical location of the airport:

Exceptions to the K-prefix rule

The 'K' prefix was only reserved for the contiguous United States (all states from California to Maine and Washington to Florida, but not Hawaii and Alaska). Hawaii and Alaska use the 'P' prefix, more commonly used in the South Pacific islands. However, unlike the continental United States, which simply adds the K prefix to the IATA airport code, each country, state, or region that uses the 'P' prefix is assigned a second letter.

For example, Hawaii is assigned 'H,' and so all ICAO codes within the state of Hawaii begin with 'PH.' Alaskan airports are instead given the prefix 'PA.' Honolulu (IATA: HNL) and Kahului (IATA: OGG) are, therefore, PHNL and PHOG, respectively. Alaskan Airports Anchorage (IATA: ANC) and Fairbanks (IATA: FAI) are PANC and PAFA.

Differences between the IATA and ICAO airport codes

IATA airport codes are used by commercial airlines in their operations and are assigned by the International Air Transport Association (IATA). They initially established these airport codes to facilitate international travel. More recently, IATA has started issuing codes to bus and ferry terminals, as well as train stations, to allow for better connections between these modes of transport.

ICAO airport codes are generally less recognized by commercial passengers. For example, when referring to London Heathrow Airport or Hong Kong International Airport, most passengers will simply think of LHR and HKG, not EGLL and VHHH. However, for industry professionals such as air traffic controllers and pilots, these ICAO airport codes mean much more.

With flight plans, for example, airports are identified by these codes. In addition, some other locations, such as weather forecast facilities and air traffic control offices, are also given ICAO codes.

Speaking of IATA codes, across the northern border of the US, Canada has a distinct pattern with its system. Notably, its codes begin with the letter Y - for example, Toronto (YYZ) and Vancouver (YVR). This trend dates back to the 1930s when an airport had Y for "yes" if they had a weather/radio station at the facility.

Get all the latest aviation news for North America here.

How do airports receive ICAO airport codes?

In the United States, airports that would like to be given an ICAO airport code are asked to contact the Federal Aviation Administration (FAA), which will then provide the relevant authorities with the contact information for the International Civil Aviation Organization. Airports then have to provide detailed information, including location, altitude, and length of runway, in order to obtain an ICAO airport code.

Altogether, ICAO codes generally have a more stringent structure than their IATA counterparts. There is a more consistent approach here.

What are your thoughts about airport codes in the United States? What do you make of this aspect of the industry across the continents? Let us know your thoughts on the overall factors in the comment section.