AEROMONK GUIDE

What Is an ICAO Airport Code?

Learn what ICAO airport codes are, why they normally contain four letters and how they differ from IATA codes.

An ICAO airport code is a four-letter identifier used within international aviation. ICAO identifiers are particularly important for flight operations, flight planning and aviation information systems.

How long is an ICAO code?

ICAO airport identifiers normally contain four letters. London Heathrow, for example, uses EGLL.

ICAO codes and aviation

ICAO identifiers are used by pilots, air traffic services, flight planning systems and other aviation professionals.

ICAO versus IATA

An airport can have both identifiers. Heathrow is LHR in the IATA system and EGLL in the ICAO system.

IATA codes are more familiar to travellers, while ICAO identifiers are more closely associated with aviation operations.