ORDChicago
An orchard that became O'Hare
The field began as Orchard Field. Chicago renamed it in 1949 after the naval aviator Edward “Butch” O'Hare; the code kept the orchard.
Reference · Airport codes
What code is this?
An airport can carry up to three codes. ICAO — four letters, for pilots and controllers. IATA — three letters, for tickets and bags. FAA — identifiers for the United States. Type one in and we'll tell you whose it is.
11,334 ICAO · 9,054 IATA · 21,586 FAA codes in the register
Three codes, three jobs
Most travellers only ever see the middle one.ICAO
The operational code, for charts, flight plans, weather reports and air traffic control. It also says where in the world the field is.
LettersFour
Issued byICAO, in Doc 7910, Location Indicators
StructureRegion, then usually country, then the airfield
Without oneZZZZ in a flight plan, the name after DEP/ or DEST/
In the register11,334 open fields, 16%
IATA
The commercial code, for tickets, bag tags and timetables. IATA assigns one only when an airline asks for it.
LettersThree
Issued byIATA, under Resolution 763
StructureNone: each is unique and treated as permanent
City codesOne code for several airports: WAS is DCA, BWI and IAD
Not only airportsRailway stations sold on air-and-rail tickets
In the register9,054 open fields, 12%
FAA
The US identifier, from FAA Order JO 7350.9: three letters for larger fields, letters mixed with digits for small ones.
CharactersThree or four, letters and digits
Issued byThe Federal Aviation Administration
And ICAOK + the FAA code in the 48 contiguous states: JFK is KJFK. Alaska and Hawaii use PA and PH
Kept backN, W, Y and Z: the Navy assigns N, and K and W are radio and TV call signs
In the register21,586 open fields, 30%
Same airportICAOIATAFAANote
Chicago O'Hare International AirportKORDORDORDThe usual US pattern: ICAO is K + the FAA code, and IATA matches.
The ICAO map of the world
22 letters in use · click a letterAn ICAO code is an address, built from the outside in. The first letter names a region of the world, the second usually a country within it, and the last two the airfield. A few large countries have a letter to themselves and spend only one on the country: the contiguous United States is K, Canada C, Australia Y and China Z.
E
First letterNorthern Europe
903 open fields · 15 prefixes
PrefixCountry or territoryFields
EGUnited Kingdom, Antarctica, Guernsey +3 EGLL166
EKDenmark, Faroe Islands EKCH34
EHNetherlands EHAM23
ELLuxembourg ELLX2
Why is O'Hare ORD?
IATA codes have no geography. Each one is a story.In the 1930s each airline chose its own two-letter codes; by the late 1940s there were too many airports for two letters and the codes grew to three. They follow no regional scheme. Many were fixed when the airport had another name, or when the letters it wanted were taken, and IATA almost never changes a code once issued — which is why so many do not match the name on the terminal.
MCOOrlando
An air force base on every bag tag
Orlando's airport stands on the former McCoy Air Force Base, named after Colonel Michael N. W. McCoy, and kept the base's code.
MSYNew Orleans
Moisant Stock Yards
Moisant Stock Yards: the land Moisant Field was built on, named after the aviator John Moisant. The airport has been renamed twice since, in 1960 and 2001.
BNANashville
Berry Field, NAshville
Berry Field, Nashville — after Colonel Harry S. Berry, the airport's first administrator.
GEGSpokane
Geiger Field, renamed in 1960
Geiger Field, after the Army aviation and ballooning pioneer Major Harold Geiger. It became Spokane International in 1960 and kept the code.
IADDulles
Too close to DCA
Dulles opened as DIA. IATA gives it as its example of a code changed for safety: DIA was too easily confused with Washington National, DCA.
LAXLos Angeles
The X is padding
Los Angeles was LA when codes had two letters. When they grew to three, an X was added that stands for nothing. IATA dates the change to 1947; the airport's own history gives 1950.
EWRNewark
Why Newark isn't N-anything
In the United States codes starting with N belong to the Navy, so Newark could not begin with its own initial.
MCIKansas City
Mid-Continent, still
Mid-Continent International, the TWA overhaul base the airport grew from in the 1950s. The code stayed when the new terminals opened in 1972.
CVGCincinnati / Covington
Cincinnati's airport is in Kentucky
Cincinnati's airport is in Kentucky, across the Ohio River. Its code comes from Covington, the nearest large town; CIN was already taken.
OGGKahului
A pilot called Hogg
Maui's code honours Jimmy Hogg, a Hawaiian Airlines chief pilot. The state says the navigation beacon he flew so many test flights for was named after him; Hawaiian Airlines says the authorities chose to honour him in 1957.
SUXSioux City
The code the city couldn't shake
Sioux City asked for a new code in 1988 and again in 2002, and turned down every alternative offered. In 2007 it gave up and started selling “Fly SUX” merchandise.
FATFresno
Fresno Air Terminal
Fresno Air Terminal, the airport's name when commercial service began in 1948.
YYZToronto
Why Canada starts with Y
Almost every Canadian airport code starts with Y. IATA says the prefix predates the Second World War and is believed to come from the codes of weather stations or radio beacons.
Codes outlive names
All renamings in HistoryCodeICAOWasNowSince
Names and dates from the journal piece What's in a name, where each has its source; O'Hare's from its story above.
Why they stay
Renaming an airport is a decision for its owner — a city council, a regional government, a national cabinet. The code is IATA's, and IATA calls its codes permanent: they are almost never changed, and then only for safety. The example IATA gives is not a renaming at all: Washington Dulles went from DIA to IAD so that it could not be confused with DCA.
The exception
The stories behind the names New York's Idlewild was IDL. Renamed after John F. Kennedy in December 1963, it swapped IDL for JFK a few weeks later — one of the few times a name moved the code with it.
Sources
- IATA, fact sheet: IATA location codes — Resolution 763, permanence, city codes, the history of two- and three-letter codes
- ICAO Uniting Aviation, the story behind airport codes — who uses which code, how an ICAO code is built
- ICAO Doc 7910, Location Indicators
- FAA Order JO 7350.9, Location Identifiers — who assigns US codes, the letters kept back
- FAA AIP, GEN 2.4 Location indicators — K, PA and PH
- FAA, flight plan filing guidance — ZZZZ
- Wikipedia, ICAO airport code — the usual description of each first letter's region
Counts, prefixes, the map and the decoder are computed from the register: codes from OurAirports, the FAA and Wikidata; counts and the map are of open airfields.