Editing IATA airport code (section)

===National policies===

====United States====
Since the [[U.S. Navy]] reserved "N" codes, and to prevent confusion with [[Federal Communications Commission]] [[Call signs in North America|broadcast call signs]], which begin with "W" or "K", the airports of certain U.S. cities whose name begins with one of these letters had to adopt "irregular" airport codes:
* [[Newark Liberty International Airport|EWR]] for [[Newark, New Jersey]]
* [[Tweed New Haven Airport|HVN]] for [[New Haven, Connecticut]]
* [[Norfolk International Airport|ORF]] for [[Norfolk, Virginia]]
* [[Key West International Airport|EYW]] for [[Key West|Key West, Florida]]
* [[Nome Airport|OME]] for [[Nome, Alaska]]
* [[Nashville International Airport|BNA]] for [[Nashville, Tennessee]] (whose airport's original name was ''Berry Field'')
* [[Napa County Airport|APC]] for [[Napa, California]].<ref name=sky/>
* [[Wilmington International Airport|ILM]] for [[Wilmington, North Carolina]]

This practice is not followed outside the United States:
* [[Karachi]] is [[Jinnah International Airport|KHI]]
* [[Warsaw]] is [[Warsaw Chopin Airport|WAW]]
* [[Nagoya]] is [[Chubu Centrair International Airport|NGO]]

In addition, since [[Q code|three letter codes starting with Q]] are widely used in radio communication, cities whose name begins with "Q" also had to find alternate codes, as in the case of:{{citation needed|date=August 2020}}
* [[Qiqihar]] ([[Qiqihar Sanjiazi Airport|NDG]])
* [[Quetta]] ([[Quetta International Airport|UET]])
* [[Quito]] ([[Mariscal Sucre International Airport|UIO]])
* [[Quimper]] ([[Quimper–Cornouaille Airport|UIP]])

Even this practice is not followed universally. For instance [[Owerri]] in Nigeria uses the code [[QOW]].
IATA codes should not be confused with the [[Location identifier#FAA identifier|FAA identifiers]] of U.S. airports. Most FAA identifiers agree with the corresponding IATA codes, but some do not, such as [[Saipan International Airport|Saipan]], whose FAA identifier is GSN and its IATA code is SPN, and some coincide with IATA codes of non-U.S. airports.{{citation needed|date=August 2020}}

====Canada====
{{more citations needed|section|date=February 2025}}
Canada's unusual codes—which bear little to no similarity with any conventional abbreviation to the city's name—such as [[Montréal–Trudeau International Airport|YUL]] in [[Montréal]], and [[Toronto Pearson International Airport|YYZ]] in [[Toronto]], originated from the two-letter codes used to identify weather reporting stations in the 1930s. The letters preceding the two-letter code follow the following format:
* "Y" – Indicating "yes", this letter was used when the station shared its location with an airport.
* "W" – When the weather-reporting station shared its location with no airport, this letter hinted at "Without".
* "U" – This letter was used when the station was located together with a [[non-directional beacon]] (NDB).
* "X" – Suggesting that the last two letters of a code were in use by a Canadian airport, this letter was put in place.
* "Z" – This letter indicated that an airport code had been used for the identification of an airport in the U.S.

Most large airports in Canada have codes that begin with the letter "Y",<ref>{{cite web|date=2019-03-07|title=Why Do Canadian Airport Codes Start With The Letter 'Y'? {{!}} Airport Codes Explained|url=https://www.airfarewatchdog.com/blog/50056121/y-do-all-canadian-airport-codes-start-with-the-letter-y/|access-date=2021-06-19|website=Airfarewatchdog Blog|language=en-US}}</ref>{{Unreliable source?|date=July 2021}} although not all "Y" codes are Canadian (for example, [[Yuma International Airport|YUM]] for [[Yuma, Arizona]], and [[Yantai Penglai International Airport|YNT]] for [[Yantai]], China), and not all Canadian airports start with the letter "Y" (for example, [[Bathurst Airport (New Brunswick)|ZBF]] for [[Bathurst, New Brunswick]]). Many Canadian airports have a code that starts with W, X or Z, but none of these are major airports. When the [[Transcontinental railroad#Canada|Canadian transcontinental railroads]] were built, each station was assigned its own two-letter [[Morse code]]:
* VR for [[Vancouver]]
* TZ for [[Toronto]]
* QB for [[Quebec City]]
* WG for [[Winnipeg]]
* SJ for [[Saint John, New Brunswick|Saint John]]
* YC for [[Calgary]]
* OW for [[Ottawa]]
* EG for [[Edmonton]]

When the Canadian government established airports, it used the existing railway codes for them as well. If the airport had a weather station, authorities added a "Y" to the front of the code, meaning "Yes" to indicate it had a weather station or some other letter to indicate it did not. When international codes were created in cooperation with the United States, because "Y" was seldom used in the United States, Canada simply used the weather station codes for its airports, changing the "Y" to a "Z" if it conflicted with an airport code already in use. The result is that most major Canadian airport codes start with "Y" followed by two letters in the city's name (for example, [[Ottawa Macdonald–Cartier International Airport|YOW]] for [[Ottawa|'''O'''tta'''w'''a]], [[Winnipeg James Armstrong Richardson International Airport|YWG]] for [[Winnipeg|'''W'''innipe'''g''']], [[Calgary International Airport|YYC]] for [[Calgary|'''C'''algar'''y''']], or [[Vancouver International Airport|YVR]] for [[Vancouver|'''V'''ancouve'''r''']]), whereas other Canadian airports append the two-letter code of the radio beacons that were the closest to the actual airport, such as [[Gander International Airport|YQX]] in [[Gander, Newfoundland and Labrador|Gander]] or [[Prince George Airport|YXS]] in [[Prince George, British Columbia|Prince George]].{{Citation needed|date=February 2023}}

Four of the ten provincial capital airports in Canada have ended up with codes beginning with YY, including:
* [[Toronto Pearson International Airport|YYZ]] for [[Toronto|Toronto, Ontario]]
* [[Victoria International Airport|YYJ]] for [[Victoria, British Columbia]]
* [[St. John's International Airport|YYT]] for [[St. John's, Newfoundland and Labrador]]
* [[Charlottetown Airport|YYG]] for [[Charlottetown|Charlottetown, Prince Edward Island]]

Canada's largest airport is YYZ<ref>{{Cite web|title=This is why Toronto's airport code is YYZ|url=https://www.blogto.com/city/2019/04/why-torontos-airport-code-yyz/|access-date=2021-06-19|website=Blogto.com|language=en}}</ref> for [[Toronto Pearson International Airport|Toronto Pearson]] (as YTZ was already allocated to [[Billy Bishop Toronto City Airport]], the airport was given the station code of [[Malton, Mississauga]], where it is located). YUL is used for [[Montréal–Trudeau International Airport|Montréal–Trudeau]] (UL was the ID code for the beacon in the city of [[Kirkland, Quebec|Kirkland]]. While these codes make it difficult for the public to associate them with a particular Canadian city, some codes have become popular in usage despite their cryptic nature, particularly at the largest airports. Toronto's code has entered pop culture in the form of "[[YYZ (song)|YYZ]]", a song by the rock band [[Rush (band)|Rush]], which utilizes the Morse code signal as a musical motif. Some airports have started using their IATA codes as [[brand name]]s, such as [[Calgary International Airport]] (YYC)<ref>{{cite web|title=YYC: Calgary Airport Authority |url=http://www.yyc.com/|access-date=22 March 2015}}</ref> and [[Vancouver International Airport]] (YVR).<ref>{{cite web|url=https://yvr.ca|title=Vancouver International Airport Homepage|website=Yvr.ca|access-date=2 July 2022}}</ref>

====New Zealand====
Numerous New Zealand airports use codes that contain the letter Z, to distinguish them from similar airport names in other countries. Examples include 
[[Hamilton Airport (New Zealand)|HLZ]] for [[Hamilton, New Zealand|Hamilton]], 
[[Queenstown Airport|ZQN]] for [[Queenstown, New Zealand|Queenstown]], 
and [[Westport Airport (New Zealand)|WSZ]] for [[Westport, New Zealand|Westport]].