Airlines, like many other organizations, are often known by their initials. In some cases the original form may not be well known, as in QANTAS = Queensland and Northern Territory Aerial Services.
Here is a large collection of PJs based on the names and initials of airlines. Beware that many of these are quite bad, and also that many refer to unknown and defunct airlines. I have added a few more below the link:
PIA (Please Inform Allah) is usually followed by AI (Allah Informed).
BOAC: Bend Over Again Christine (Google for Christine Keeler or Profumo scandal).
Pan Am, officially Pan American Airways: Pandemonium Scareways.
GARUDA (Indonesia): Good Airline Run Under Dutch Administration
And TWA has associated jokes like “Do you want TWA coffee or TWA tea?”, although not all their passengers would have been familiar with the American word here.
There are a few similar ones like these for railway companies.