DOS Airlines - Everybody pushes the airplane until it glides, then jumps on and lets the plane coast until it hits the ground again, then push again, jump on again and so on. 

DOS with QEMM Airlines - The same thing but with more leg room to push. 

MAC Airlines - All the stewards, stewardesses, captains, baggage handlers and ticket agents look the same, act the same and talk the same. Every time you ask questions about details, you are told you don't need to know, don't want to know, and everything will be done for you without you having to know, so just shut up. 

OS/2 Airlines - To board the plane, you have your ticket stamped 10 different times by standing in 10 different lines. Then you fill out a form showing where you want to sit and whether it should look and feel like an ocean liner, a passenger train, or a bus. If you succeed in getting on board the plane and the plane succeeds in getting off the ground, you have a wonderful trip... except times when the rudder and flaps get frozen in position, in which case you have time to say your prayers and get yourself prepared before the crash. 

WINDOWS Airlines - The airport terminal is nice and colourful, with friendly stewards and stewardesses, easy access to the plane, and an uneventful takeoff ... then the plane blows up without warning whatsoever. 

NT Airlines - Everyone marches out on the runway, says the password in unison and forms the outline of a plane. Then they all sit down and make a whooshing sound like they're flying. 

UNIX Airlines - Everyone brings one piece of the plane with them when they come to the airport. They all go out on the runway and put the plane together piece by piece, arguing constantly about what kind of plane they are building.