Online Tool Store
· 4 min read
How to Look Up an Airport Code Correctly
Manesh Jayawardhana
CIO & Co-founder
You book a flight to LON and turn up at Heathrow. The flight is from Gatwick, an hour and a half away, because LON isn’t an airport — it’s a city code covering all six London airports.
Airport codes look like a simple lookup and contain two genuine traps: the city-versus-airport distinction, and the fact that two completely different code systems are in use.
IATA and ICAO
IATA codes are three letters. They’re what appears on tickets, boarding passes and baggage tags — the codes travellers see. LHR, JFK, CMB.
ICAO codes are four letters, used operationally by air traffic control and in flight planning. Their first letter or two encodes a region: E for northern Europe, K for the contiguous United States, V for South Asia. Heathrow is EGLL, JFK is KJFK, Colombo is VCBI.
If you’re reading a flight plan, using an aviation API, or looking at a NOTAM, you’ll meet ICAO. If you’re booking a holiday, you’ll meet IATA. They’re not interchangeable and there’s no reliable way to convert one to the other by pattern.
City codes are the actual trap
Metropolitan areas with several airports get a city code that covers all of them: LON for London, NYC for New York, PAR for Paris, TYO for Tokyo.
Searching a city code returns flights to every airport in the region, which is genuinely useful when you’re comparing options and genuinely dangerous when you assume it’s a specific airport. LON includes Heathrow, Gatwick, Stansted, Luton, City and Southend — the extremes of which are well over two hours apart.
Some cities also have a code that looks like an airport code but isn’t: it’s the metropolitan area code, and it happens to share a name with the main airport.
Always confirm the actual airport, not just the code, before booking ground transport.
| Code | Type | Covers |
|---|---|---|
| LHR | IATA airport | Heathrow only |
| LON | IATA city | All six London airports |
| EGLL | ICAO | Heathrow, operational |
| NYC | IATA city | JFK, LaGuardia, Newark |
Why codes look unrelated to city names
Many predate the current name of the airport or city, or come from an old aerodrome that occupied the site.
Codes are historically assigned by IATA and change very rarely, because they’re printed into ticketing systems, baggage handling and decades of records worldwide. The inertia is enormous, which is why airports renamed decades ago still carry codes referencing something that no longer exists.
Common mistakes to avoid
- Booking to a city code and assuming a specific airport.
- Using an ICAO code where an IATA code is expected, or vice versa.
- Assuming a code maps predictably to a city name.
- Confusing similar codes for airports in different countries — several three-letter combinations are near-misses.
- Arranging airport transfer before confirming which airport the flight actually uses.
How to do it with Airport Code Lookup
The Airport Code Lookup resolves both code systems and flags city codes.
- Enter a three-letter IATA code, a four-letter ICAO code, or a city name.
- Check the country as well as the city — several codes look plausible for more than one place.
- For multi-airport cities, confirm whether you have the city code or a specific airport code.
- Note the ICAO code too if you’re working with flight planning tools.
IATA’s own code search is the authoritative source. Other travel tools are in the tools directory.
Frequently asked questions
What’s the difference between IATA and ICAO codes?
IATA codes are three letters, used on tickets and baggage tags. ICAO codes are four letters used operationally by air traffic control, with the first letters encoding a region.
Why do some cities have their own code?
Multi-airport cities have a metropolitan code — LON, NYC, PAR — covering all their airports. Booking against one searches all of them, which is sometimes wanted and sometimes a two-hour transfer you didn’t plan.
Why do codes seem unrelated to city names?
Many predate the current name or come from an old aerodrome. Codes are assigned historically and almost never change, because they’re embedded in ticketing and baggage systems worldwide.
Final thought
Before booking anything on the ground, confirm the airport rather than the code. A city code is a search convenience, not a destination.