USA air travel rules: Six ways you can get booted from your plane seat

It's in their contracts of carriage: When you buy an airfare airlines do not "guarantee" a particular seat, schedule or flight. And airlines can be pretty persnickety about who they fly and where they seat them. Back when I used to work for Eastern Air Lines, an employee flying on a company ticket had to wear a suit and tie in order to be accepted for transportation. We always flew in first class if there were seats, but one day I showed up at the check-in desk with a nice suit but no tie and I was bumped back to economy. "The way you're dressed, you don't deserve to fly at all!" sniped the ticket agent.

But it happens to paying passengers, too, and for sometimes unpredictable reasons. Actor Andie MacDowell was booted back to "tourist class" recently because she carried a pet pooch on board but was sitting in the first-class bulkhead row, which meant there was no under-seat area for the dog and its carrier (this is typical of most bulkhead rows). Why the Four Weddings and a Funeral actress was sitting in that row while transporting an animal isn't clear, since she let the airline know she was bringing a pet on board, but she was ignominiously sent back to an economy-class seat and she wasn't having it on Twitter. "@AmericanAir HELP I paid for first class & they put me in tourist because of my dog that I pre-booked & paid for," she tweeted.

But it's not just airline employee dress codes and pets that can get you booted back to coach — or off the plane entirely.

1. The Air Marshall needs your seat

These guys still fly to protect you, and they're sometimes seated without prior warning. If one of them shows up and needs your seat, you'll either be bumped off the flight entirely or reassigned. And you won't even get an explanation (obviously, the authorities don't want you to blab that there's an air marshal on board).

2. You messed with a crewmember.

When Bobby Abtahi, a Dallas attorney, was rushing through one of those large revolving doors at New York's LaGuardia Airport, he supposedly "cut off" a Virgin America flight attendant who was attempting to enter at the same time. Abtahi was booted off his flight after the flight attendant complained to the captain flying his plane. At least Virgin later apologised for the "misunderstanding" and refunded his fare.

3. You — or your child — won't listen to crewmember instructions.

Actually, if you do anything to annoy cabin crew or fail to obey their instructions and those "lighted placard signs." When singer Sarah Blackwood of Walk Off the Earth couldn't get her toddler to sit down and fasten his seatbelt just before takeoff, her United Airlines flight returned to the gate and both were invited to deplane. "That's how babies are," she reportedly said. Not a few other parents and their issues have been booted for unruly behavior — theirs or their progeny's.