Originally Posted by
Yaatri
The flexibility afforded by 4 letters makes it easier to assign recognisable codes to more cities than is possible with 3 letters. But I like three letter codes.
But the ICAO 4-letter codes aren't based on pronunciation (or city name) like the IATA codes are. They're based entirely on location, as a previous poster explained. EGLL is much less recognizable than LHR, if you're not familiar with the codes.