Editing ICAO airport code (section)

== Structure ==
The first one or two letters of the ICAO code indicate the country; the remaining letters identify the airport. For example, the ICAO code for [[Heathrow International Airport]] in London, is EGLL, with EG reflecting that it is based in the [[United Kingdom]]. By contrast, IATA codes do not provide geographic reference. For example, LHR, representing Heathrow, does not enable one to deduce the location of the airport LHV with any greater certainty; it is [[William T. Piper Memorial Airport]] in [[Lock Haven, Pennsylvania]] in the [[United States]].

There are a few exceptions to the regional structure of the ICAO code for political or administrative reasons:
* [[RAF Mount Pleasant]] air base in the [[Falkland Islands]], for instance, is assigned the ICAO code EGYP as though it were in the United Kingdom, but nearby civilian [[Port Stanley Airport]] is assigned SFAL, consistent with [[South America]].
* [[Saint Pierre and Miquelon]] is controlled by France, and airports there are assigned LFxx as though they were in Europe.
* [[Kosovo]] is assigned the code BKxx grouping it with [[Greenland]] and [[Iceland]] rather than its geographical neighbors which have Lxxx (described below).
* [[Jerusalem International Airport]] was assigned both LLJR (its Israeli persona) as well as OJJR (its Jordanian persona), but the airport itself fell into disuse.

[[Western Sydney Airport]], due to open in 2026 has the ICAO code YSWS. In Australia, the second letter is usually linked to the airport's [[Flight information region|FIR]]. However, Sydney's FIR has been non-existent since the introduction of [[The Australian Advanced Air Traffic System|TAAATS]].

In the contiguous United States and Canada, many airports have ICAO codes that are simply copies of their three-letter [[IATA]] codes, with the geographical prefix added on (e.g., YEG and CYEG both refer to [[Edmonton International Airport]], while IAD and KIAD both refer to [[Washington Dulles International Airport]]). This similarity does not extend to [[Alaska]] (PAxx), [[Hawaii]] (PHxx), or U.S. territories. [[Kahului Airport]] on [[Maui]], for instance, has an IATA code of OGG and an ICAO code of PHOG.

ICAO airport codes do not begin with I or J or X or Q, though the [[Jezero (crater)|Jezero Crater]] on [[Mars]] is assigned the special ICAO code JZRO.<ref>{{Cite web |date=April 19, 2021 |title=NASA's Ingenuity Mars Helicopter Succeeds in Historic First Flight |url=https://www.nasa.gov/news-release/nasas-ingenuity-mars-helicopter-succeeds-in-historic-first-flight/ |access-date=May 16, 2024 |website=[[NASA]]}}</ref> Codes beginning with I (Ixx and Ixxx) are often used for [[navigational aid]]s such as radio beacons, while the [[Q code]] is reserved for international radiocommunications and non-geographical special use.

In [[Russia]], the Latin letter X, or its [[Morse Code|Morse]]/[[ITA2|Baudot]] Cyrillic equivalent [[Ь]], are used to designate government, military, and experimental aviation airfields in internal airfield codes similar in structure and purpose to ICAO codes but not used internationally.<ref>[http://www.caica.ru/DocAni/manual_of_4_letter_indexes/Indexes_of_Airports.pdf Index of four-character airfield codes in Russia]</ref> ZZZZ is a pseudo-code, used in [[flight plan]]s for aerodromes with no ICAO code assigned.

ICAO codes are sometimes updated. [[Johannesburg Airport]] in [[Johannesburg]], South Africa, for instance, was formerly known as Jan Smuts International Airport, with code FAJS. When the airport was renamed O. R. Tambo International Airport, its ICAO code was updated to FAOR.

Some airports have two ICAO codes, usually when an airport is shared by civilian and military users. [[Frankfurt Airport]] in [[Frankfurt]], Germany, for instance, has been assigned ICAO code EDDF while [[Rhein-Main Air Base]] was assigned ICAO code EDAF until its closure. [[Sion Airport]] in Switzerland has code LSGS while its military facilities have the ICAO code LSMS. [[Brussels Airport]] in [[Brussels]], Belgium, has the ICAO code EBBR for its civilian facilities, and [[Melsbroek Air Base]] has been assigned ICAO code EBMB, even though the two airports share runways and ground and air control facilities.