Some (or many?) airlines use a city code rather than a specific airport code, even for baggage tagging, as an example NYC rather than JFK
, if it is the only airport they fly to in the New York area.
Here in Buenos Aires, we have EZE
... but in my notes, often, I write BUE instead.
I always write references to New York City as NYC... The place we land is JFK
Amsterdam is to most AMS
, but many airlines use SPL for Schiphol.
Paris is PAR, while we think of CDG
How about Tokyo, I write it TYO, rather than NRT
On my pilot paperwork and forms, I have to use 4 letter ICAO codes anyway...
And believe me, some of you guys know them BETTER than me... a pilot.