An airport code is a short alphanumeric identifier assigned to an airport, used across aviation systems to name locations precisely and efficiently.
How It Works#
Two separate coding systems are in active use worldwide. The IATA code (International Air Transport Association) is a three-letter code used mainly in commercial aviation, ticketing, and baggage handling. Examples include LAX for Los Angeles International and LHR for London Heathrow.
The ICAO code (International Civil Aviation Organization) is a four-character code used by air traffic control, flight planning, and meteorology. ICAO codes are structured by region. The first letter (or two letters) identifies a world region or country, and the remaining characters identify the specific airport. Los Angeles International, for example, carries the ICAO code KLAX.
In the United States, most ICAO codes simply add a "K" prefix to the IATA code. Canada uses "C" as its prefix. This pattern does not apply globally. Heathrow's IATA code is LHR, but its ICAO code is EGLL, reflecting the UK's regional identifier.
Smaller airports and heliports sometimes hold only an ICAO code, or a local identifier assigned by a national authority such as the FAA. These local identifiers often use numerals or additional letters not found in IATA codes.
Example in Aviation#
A dispatcher filing an IFR (Instrument Flight Rules) flight plan from Denver to Miami enters departure and destination as KDEN and KMIA. These ICAO codes feed directly into air traffic control systems, weather briefing tools, and navigation databases. The same flight appears on passenger booking systems as DEN to MIA, using the IATA codes.
This dual system means a single airport carries two valid identifiers used in different contexts. Pilots and dispatchers switch between them depending on the tool or document in front of them.
Why It Matters#
Airport codes remove ambiguity from aviation communications. Dozens of cities share similar names worldwide. A code like YSSY (Sydney Kingsford Smith, Australia) leaves no room for confusion, regardless of language or accent.
Student pilots encounter ICAO codes early in training. Every METAR (aviation weather report), NOTAM (Notice to Air Missions), and flight plan uses ICAO identifiers. Recognizing and using codes correctly is a basic operational skill.
Key Takeaways#
- IATA codes are three letters, used in ticketing and baggage systems.
- ICAO codes are four characters, used in flight planning and ATC.
- US airports typically form their ICAO code by adding "K" before the IATA code.
- Weather reports, NOTAMs, and flight plans all use ICAO codes.
- Some small airports hold only a local identifier, with no IATA code assigned.