Definition
A four-letter code assigned by the International Civil Aviation Organization (ICAO) that uniquely identifies an airport or weather reporting station worldwide. In the contiguous United States, these identifiers begin with the letter K followed by the three-letter location code (for example, KORD for Chicago O'Hare). Other regions use different first letters: C for Canada, M for Mexico and parts of Central America, P for Alaska and the Pacific, and so on.
Plain English
A four-letter code that names a specific airport or weather station anywhere in the world. In the lower 48 United States, the code starts with K and is followed by the airport's three-letter code.
Context Anchor
Seen at the beginning of a Terminal Aerodrome Forecast, and also in aviation weather products such as METARs.
Derivation
ICAO stands for International Civil Aviation Organization, the United Nations body that sets worldwide aviation standards. The four-letter system was created so every airport on the planet has one unique code, regardless of language or country.
Why Pilots Care
Ensures the pilot is using weather information for the correct airport, which directly affects route planning, fuel calculations, and go/no-go decisions.
Intuition Check
Station does not mean a radio station or passenger terminal here. It means the airport or weather reporting location; the identifier is the code for that location, not the forecast itself.
Example Sentence 1
The TAF began with KMEM, telling the pilot the forecast was for Memphis International Airport.
Example Sentence 2
Before filing the flight plan the pilot verified the ICAO station identifier matched the destination airport listed on the chart.