No, all codes are not obvious, I'll agree here with the original poster.
Even if the airline codes at your local airport
are very familiar to you, they're not
that easy for people from the other side of the pond.
How many of you in the US are familiar with codes like: JZ (Skyways, Sweden), QI (Cimber, Denmark),
DM (Maersk, Denmark), NB (Sterling, Denmark) or BU (Braathens, Norway)...?
Not too easy, huh??
The big, international, carrier codes are probably easy and well-known to most of us, but not all the smaller airlines.
Exactly the same applies for the use of airport 3-letter codes, everyone know about MIA, JFK, HKG, FRA SYD etc etc, but how many knows about airports like BMA, ARN, NYO?? (use the search function...
Just my .02 euros...