Airports And The Elusive Number 3: What's The Deal?

Every airport in the world has a three-letter code, which is used to easily identify airports worldwide. These codes are more than random letters – they are identifiers that help ensure passengers board the right plane, especially when heading to a city with multiple airports. The three-letter combination gives 17,576 possible codes, whereas a two-letter system only allows for 676. The International Air Transport Association (IATA), a trade association for the global airline industry, is responsible for assigning these codes. When a new airport is planned, or an existing one undergoes significant changes, a request is submitted to IATA for an official three-letter code.

Three-letter airport codes

The use of three-letter airport codes arose from the convenience it brought to pilots for location identification in the 1930s. Initially, pilots in the United States used a two-letter code from the National Weather Service (NWS) for identifying cities. However, as the number of airports grew, a three-letter code system was adopted, providing 17,576 possible combinations compared to only 676 with two letters.

The first choice for IATA when assigning a three-letter code is to use the first three letters of the city's name, such as LAS for Las Vegas or BOS for Boston. If there is more than one airport in a city, IATA may choose an abbreviation for the airport, like JFK for New York's John F. Kennedy International Airport. Alternatively, they may use a combination of letters from the city's name, preferably starting with the same first letter, such as AHN for the airport in Athens, Georgia.

Occasionally, this results in humorous codes like LOL for Derby Field Airport near Lovelock, Nevada, or OMG for Namibia's Omega Airport. No two airports can share the same three-letter code. If a new airport cannot be assigned a code using the methods above, the code may be based on the history of the area, like MCO for Orlando International Airport, which was once McCoy Air Force Base.

In addition to the IATA three-letter codes, the International Civil Aviation Organization (ICAO) also issues airports a four-letter code. This code is primarily used by air traffic controllers and air navigation service providers, while the IATA code is more commonly seen by the general public.

Triple takeoff/landing capabilities

Triple takeoff and landing capabilities are a necessity for many large airports, allowing multiple aircraft to arrive and depart within a short time frame.

Istanbul Airport

In February 2024, Türkiye announced its plans to install a system at Istanbul Airport that would enable three aircraft to independently land and take off simultaneously. This system, known as "Triple RWY Operations TRO", is set to optimise the use of existing resources at the airport. Works on the project were initiated in 2022, with trials expected to begin in 2024.

Istanbul Airport is one of the biggest civil aviation hubs in the world, serving around 76 million passengers in 2023. With the introduction of the new system, the airport will be able to accommodate three aircraft performing independent triple parallel landings and takeoffs at the same time, enhancing operational efficiency.

Other Airports with Triple Takeoff and Landing Capabilities

Several airports around the world are already capable of triple parallel landings and takeoffs. These include:

• Amsterdam Airport Schiphol
• Beijing Capital International Airport
• Beijing Daxing International Airport
• Cairo International Airport
• Charlotte Douglas International Airport
• Cincinnati/Northern Kentucky International Airport
• Dallas Fort Worth International Airport
• Denver International Airport
• Detroit Metropolitan Airport
• Dulles International Airport
• George Bush Intercontinental Airport
• Guangzhou Baiyun International Airport
• Hartsfield–Jackson Atlanta International Airport
• Hong Kong International Airport
• Indira Gandhi International Airport
• Incheon International Airport
• King Abdulaziz International Airport
• Kuala Lumpur International Airport
• Kuwait International Airport
• Memphis International Airport
• Minneapolis−Saint Paul International Airport
• Nashville International Airport
• O'Hare International Airport
• Orlando International Airport
• Philadelphia International Airport
• Salt Lake City International Airport
• Shanghai Pudong International Airport
• St. Louis Lambert International Airport
• Suvarnabhumi International Airport
• Wichita Falls Regional Airport

Multiple airports in one city

Many cities around the world have multiple airports. This is often to avoid congestion, particularly in large cities with high demand for air travel.

For example, Washington D.C. has two airports: Washington-Dulles (IAD) and Washington-National (DCA). The former is located about 25 miles from the National Mall and is used by major international carriers such as EgyptAir, KLM, and Emirates. The latter is located across the river from the National Mall and is constrained by the city on one side and a river on the other, limiting its capacity for expansion. As a result, Washington-National primarily serves domestic flights within a 1,250-mile radius.

Another example is London, which has multiple airports, including Heathrow, Gatwick, and London City Airport. By having multiple airports, London can accommodate a larger number of passengers than if all flights were funnelled through a single airport.

Other cities with multiple airports include New York City, Los Angeles, Paris, Tokyo, Stockholm, San Francisco, Boston, Toronto, Chicago, Miami, and many others.

In some cases, cities have multiple airports to cater to different types of flights, such as international and domestic. For instance, domestic flights typically use smaller aircraft that can operate from shorter runways. Additionally, having multiple airports allows for competition between airlines and provides passengers with more options for their travel plans.

Four or more parallel runways

While triple takeoff/landing capabilities are a necessity for many large airports, there are only a few airports with four or more parallel runways. These airports can handle a high volume of aircraft arrivals and departures in a short amount of time.

In the United States, the Federal Aviation Administration (FAA) dictates that airports must have at least 3,000 feet (910 m) between runways for parallel approaches. However, the FAA can grant special permission for parallel approaches with less separation if deemed necessary.

• Hartsfield–Jackson Atlanta International Airport (KATL): 5 parallel runways (08L/26R, 08R/26L, 09L/27R, 09R/27L, 10/28).
• Denver International Airport (KDEN): 4 parallel runways (16L/34R, 16R/34L, 17L/35R, 17R/35L) and 2 more parallel runways (07/25, 08/26).
• Dallas/Fort Worth International Airport (KDFW): 5 parallel runways (17L/35R, 17C/35C, 17R/35L, 18L/36R, 18R/36L) and 2 more parallel runways (13L/31R, 13R/31L).
• Detroit Metropolitan Airport (KDTW): 4 parallel runways (03L/21R, 03R/21L, 04L/22R, 04R/22L) and 2 more parallel runways (09L/27R, 09R/27L).
• Los Angeles International Airport (KLAX): 4 parallel runways (06L/24R, 06R/24L, 07L/25R, 07R/25L).
• Chicago O'Hare International Airport (KORD): 5 parallel runways (09L/27R, 09R/27L, 10L/28R, 10C/28C, 10R/28L) and 2 more parallel runways (04L/22R, 04R/22L).

Outside of the United States, there are only three airports with four parallel runways:

• Paris Charles de Gaulle Airport (LFPG)
• Istanbul Airport (LFTM)
• Shanghai Pudong International Airport (ZSPD)

Some other airports with triple parallel landing capabilities include:

• Amsterdam Airport Schiphol
• Beijing Capital International Airport
• Cairo International Airport
• Charlotte Douglas International Airport
• Cincinnati/Northern Kentucky International Airport
• Dulles International Airport
• George Bush Intercontinental Airport
• Guangzhou Baiyun International Airport
• Hong Kong International Airport
• Indira Gandhi International Airport
• King Abdulaziz International Airport
• Kuala Lumpur International Airport
• Memphis International Airport
• Nashville International Airport
• Orlando International Airport
• Philadelphia International Airport
• Salt Lake City International Airport
• St. Louis Lambert International Airport
• Suvarnabhumi International Airport
• Wichita Falls Regional Airport

While triple or quadruple parallel runways are impressive, simultaneous landings and take-offs are actually quite rare. This is because airports often prioritize one runway for take-offs and another for arrivals, and staggered approaches reduce air traffic control precautions.

Primary airports

The United States Federal Aviation Administration (FAA) has a system for categorizing public-use airports. This system is primarily based on the level of commercial passenger traffic through each facility.

• Non-hub primary: Airports handling over 10,000 but less than 0.05% of the country's annual passenger boardings.
• Small hub primary: Airports with 0.05-0.25% of the country's annual passenger boardings.
• Medium hub primary: Airports handling 0.25-1% of the country's annual passenger boardings.
• Large hub primary: Airports handling over 1% of the country's annual passenger boardings.

Most people are familiar with large hub primary airports, such as John F. Kennedy International in New York City, Hartsfield-Jackson Atlanta International Airport, Chicago O'Hare International, or Los Angeles International. However, primary airports also include airports in smaller cities and regional airports meant to provide flight availability to people in more rural regions.

Frequently asked questions