How Airport Codes Work Around the World

DALLAS — Have you ever wondered why the tag on your checked bag bears three letters that correspond to the airport you are departing from? These three letters are known as International Air Transport Association (IATA) airport codes, and they have been in use since the early days of aviation. It is truly remarkable to consider that the commercial aviation industry, as we know it, would not be possible without these codes.

The International Air Transport Association (IATA) is a global trade organization that represents over 300 airlines from around the world and provides support for airport operations in 194 countries. The association is responsible for assigning and managing the three-letter codes that you see printed on luggage tags and flight tickets.

The practice of assigning codes to airports originated in the 1930s. Back then, airport codes consisted of a combination of two letters. However, as the number of airports increased and the aviation industry continued to advance, this method became impractical and difficult to manage.

In the 1960s, IATA introduced the three-letter code system that we are familiar with today. This system was established through IATA Resolution 763, which outlined a set of requirements that entities requesting codes for their airports must meet.

Assigning airport codes can sometimes be a very difficult task, as they cannot be connected to more than one airport in most cases. Photo: Adrian Nowakowski/Airways

Assigning Airport Codes

Presently, there is no specific procedure in place for the assignment and approval of airport codes, except for the requirement that each airport must be allocated a unique code and that no code can be duplicated.

Typically, it is the responsibility of the airport itself to propose a list of codes to IATA, which then evaluates their availability and grants approval. The most common approach to assigning codes involves using the first three letters of the city or airport name, like MIA for Miami, MAD for Madrid, or FRA for Frankfurt. However, in certain instances, such as with Santiago de Chile, the desired code was already in use by San Diego International Airport (SAN), necessitating the selection of an alternative code (SCL) for the Chilean airport.

Another method employed for assigning airport codes is to combine the initial letters of the complete airport name, as evident in codes like JFK for New York—John F. Kennedy, CDG for Paris—Charles de Gaulle, or DFW for Dallas—Fort Worth. Interestingly, Toronto Pearson International Airport is assigned the IATA code YYZ, which does not include any letters from either the airport or the city itself.

Canada’s third-largest airport in Calgary was assigned “YYC” as its IATA code for commercial operations, even though it is not very similar to the city’s name. Photo: Daniel0685 (CC BY-SA 2.0)

Canadian Airport Codes

In Canada, all commercial airports are assigned IATA codes that commence with the letter ‘Y’. This practice originated from the reuse of codes initially utilized to identify weather stations during the country’s earliest stage of aviation in the 1930s.

The use of a code starting with ‘Y’ indicated that the weather station was situated at an airport, while a code starting with ‘W’ indicated that the weather station was located in an area without an adjacent airport. Additionally, codes beginning with ‘U’ were employed when the weather station was co-located with an NDB navaid, whereas ‘Z’ codes were assigned to stations situated within the United States.

Consequently, certain Canadian airport codes can provide insights into the location of the airport, like YVR for Vancouver, while others, such as YQX for Gander International Airport, may not immediately reveal their whereabouts. Toronto follows this same convention, adhering to the rule.

With up to six commercial airports serving as passenger entries to London, the city possesses a general IATA code of ‘LON’, which generalizes traffic flow to the whole city. Diagram: Adrian Nowakowski/Airways

Cities With More Than One Airport

In instances where the volume of traffic and passenger movement in a large city necessitates the simultaneous operation of two or more airports, the city can make a request to IATA to assign a global code that encompasses all the airports serving that location.

This arrangement enables passengers to search for flights to the entire city rather than having to search for each individual airport separately.

This practice is widespread in major cities across the globe. For instance, notable examples include London (LON), New York (NYC), Stockholm (STO), and Rio de Janeiro (RIO). However, if a passenger is seeking flights to Montreal, they may encounter the challenge of needing to identify that the code ‘YMQ’ corresponds to the city.

Since 1944, the International Civil Aviation Organization (ICAO) has played a pivotal role in shaping and advancing the aviation industry, enjoying recognition from nearly all member states of the United Nations.Photo: Kurt Raschke (CC BY-SA 2.0).

ICAO Codes

In addition to IATA, the International Civil Aviation Organization (ICAO) has established its own airport coding system that encompasses not only commercial airports but also all other airstrips worldwide. Each small aerodrome, air base, commercial airport, and even airstrip in Antarctica is assigned a unique ICAO code.

Unlike IATA codes, ICAO codes consist of four letters instead of three, allowing for a broader range of possibilities with a total of 456,976 different combinations.

The limited number of combinations poses a significant challenge for IATA, as over 10,000 airport codes have been registered since the 1960s, and the total number of three-letter combinations is only 17,576. Consequently, entities requesting ICAO codes for their airports have less influence over the final assignment and are typically granted codes based on availability.

Rephrased: The key differentiation between IATA and ICAO codes is rooted in the information encapsulated within the ICAO codes, as they provide significant details regarding the geographical location of a specific aerodrome on a global scale. This is achieved through regional classification, where the first two letters of an ICAO code indicate the country to which the code corresponds.

Pursuing the correct organization of aerodromes and airspace, the ICAO established a series of world regions with an identifying initial letter, which is present on every ICAO code. Photo: Hytar/Wikimedia Commons.

ICAO World Regions

During the 1940s, the International Civil Aviation Organization (ICAO) devised a system that assigned 22 distinct letters to each world region and country. This allocation was intended to facilitate geographical differentiation and simplify the process of assigning codes to countries. Notably, in a four-letter ICAO code, the initial letter always indicates the world region where the country is located.

For example, ‘E’ represents Northern Europe, ‘S’ signifies South America, and ‘U’ designates former Soviet Union countries like Belarus, Kazakhstan, and Ukraine. The second letter in the code denotes the specific country within the region.

For instance, ‘EG’ corresponds to the United Kingdom, ‘SB’ represents Brazil, and ‘UK’ stands for Ukraine. Consequently, ‘LFPO’ refers to Paris Orly Airport, with ‘L’ indicating the ICAO World Region of Southern Europe, ‘F’ denoting France, and ‘PO’ representing Paris Orly.

However, complexities arise when dealing with larger countries such as Canada, Russia, and the United States. This is due to the fixed allocation of two letters in the ICAO code for the country, leaving only 676 combinations available for specific airport codes. Given that the United States currently has over 5,000 civil airports, registering all the necessary ICAO codes for these airports presents a challenge.

To address this issue, the ICAO granted the United States special status by allowing the country to use a one-letter country code (‘K’) followed by its three-letter IATA code instead of the typical two-letter code. This arrangement expanded the potential for assigning up to 17,576 distinct ICAO codes for the various aerodromes in the United States.

Canada also encounters a similar challenge, with the letter ‘C’ designated as the initial national code for every aerodrome within Canadian territory. Coupled with the unique coding system for Canadian airports, this makes them some of the most distinctive airports globally.

LAX, which is the IATA code for Los Angeles International Airport, has become a worldwide marketing sign for the US West Coast city. Photo: Andre M./Wikimedia Commons

When to Use IATA or ICAO Codes

With the establishment of separate airport coding systems by two global organizations, IATA and ICAO, entities now have the flexibility to utilize these codes for different purposes, each serving its own distinct function.

ICAO codes are primarily employed for internal and technical operations within the aviation industry. These codes encompass not only commercial airports but also all airstrips and military air bases worldwide. Air navigation service providers, air traffic controllers, pilots, and airlines make use of these codes for a range of purposes, including the identification of airports on flight plans, communication exchanges, and handling classified documents.

In contrast, IATA codes find their predominant use in situations involving the general public and passengers. These three-letter codes, often similar to the airport name or city, are easily recognizable by passengers and do not necessitate specialized aviation knowledge. Consequently, airlines and airports incorporate IATA codes into their commercial operations, route networks, marketing campaigns, and luggage management and sorting processes.

By utilizing a three-letter code rather than the full airport name, the likelihood of confusion during luggage transfers is significantly reduced, leading to a higher rate of accurate baggage delivery to the intended destination.

London Stansted Airport Media Centre

Interesting Airport Codes Worldwide

The assignment of airport codes, given the vast number of airports worldwide, can occasionally lead to peculiar situations where the resulting three- or four-letter codes form amusing names unrelated to the airports themselves.

For instance, the IATA code for Omega Airport in Namibia is OMG; traveling from Funafuti International Airport in Tuvalu to Derby Field in the US would involve a journey from FUN to LOL; and individuals with a fondness for animals would find it amusing to take a flight from Cascais Municipal Airport in Portugal to Dongola Airport in Sudan, resulting in the codes CAT to DOG.

These instances serve as just a few examples of the delight one can find in exploring airport codes from around the world. Are you intrigued by the amusing and sometimes unexpected airport codes that emerge from the aforementioned assignment process? We would love to hear about the unique airport codes in your city or country via our social media channels!

Featured image: Piviso (CC-0)

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