A station identifier is a four-letter code assigned by the International Civil Aviation Organization (ICAO) that uniquely identifies a specific airport or weather observing station in aviation weather reports such as METARs and TAFs.
How It Works#
Every ICAO station identifier follows a regional prefix system. The first letter indicates the broad geographic region. The remaining letters narrow the location down to a specific country, area, and station.
In the United States, all identifiers begin with K. Los Angeles International Airport, for example, is KLAX. In Canada, most identifiers begin with C, so Vancouver International is CYVR. Many European identifiers begin with E (northern Europe) or L (southern Europe), so London Heathrow is EGLL and Rome Fiumicino is LIRF.
Some US stations fall outside the K-prefix rule. Alaska uses PA, Hawaii uses PH, and Guam uses PG. These reflect ICAO's Pacific regional designator rather than the continental US convention.
The station identifier always appears as the first element in a METAR or TAF. A decoder reads it before anything else to confirm which airport the weather data describes.
Example in Aviation#
A pilot preparing for a flight from Denver to Phoenix pulls up the destination METAR. The report begins: KPHX 121753Z 29012KT 10SM SKC 34/06 A2992. The first element, KPHX, is the station identifier for Phoenix Sky Harbor International Airport. The pilot immediately knows this weather data belongs to the correct destination, not another nearby airport.
Without the identifier, a pilot could easily confuse weather reports from adjacent stations. In a busy terminal area with several nearby airports, picking the wrong METAR could mean planning a flight on completely incorrect conditions.
Why It Matters#
Every METAR and TAF starts with a station identifier. Knowing how to read it correctly is the first step in parsing any weather report. A student pilot who misreads an identifier might review weather for the wrong airport entirely.
Understanding the regional prefix system also helps pilots quickly sanity-check a report. If a METAR for a US airport does not start with K (or a recognized US Pacific prefix), something is wrong with the source or the query.
Key Takeaways#
- ICAO station identifiers are always four letters long and globally unique.
- US continental airports begin with K; Canada uses C; regions vary across Europe and the Pacific.
- The identifier is always the first element in a METAR or TAF.
- Misreading or ignoring the identifier can cause a pilot to act on weather data for the wrong airport.
- Alaska, Hawaii, and US Pacific territories use regional prefixes other than K.