I agree that ICAO is easier to keep track of and are more systematic, but sometimes they just make no sense. For example, EGLL?
E - Region
G - England
LL - visible confusion
Sure, ICAO is definitely more regulated but I a TAA is much easier to understand. If you told a general person you were going to EGLL, they would be like:
But if I told them LHR, they would be like
Just the general person, IATA is much easier to understand, and therefore when I’m just casually talking, I will never use ICAO even in virtual airline chats. I will use IATA 99% of the time.
I hear it has to do with like if they had a radar or something and if it was yes, it was a Y that stated the code.
Long story short, every airport except for like three had radars so now there are three airports in Canada that randomly start with a Z.
That’s what I heard at least.