Last year, US commercial air carriers bumped 40,000 passengers, and that's not counting those who voluntarily gave up their seats. United Airlines abruptly changed 3,765 travelers' plans with the involuntary bump, with 62,895 bailing out by choice, NBC Boston reports.

Read the fine print on any ticket and you'll see that when you board a commercial airliner, you are completely at the mercy of the airlines - they decide who flies and who doesn't. Period.

The US Department of Transportation can't make airlines change that policy, but it does make them offer stymied passengers compensation packages.

Roughly, the rules, which can be haggled, are as follows: If the airline can get you on another flight to your destination within an hour, they don't have to pay you anything.

If they can't get you on an airplane within an hour, they have to pay you 200 percent of your original fare (up to $675).

If they can't make the two-hour window, they must offer 400 percent of the fare (up to $1,350).

In an op-ed on CNN's website, aviation lawyer Thatcher A. Stone said that when he and his then 13-year-old daughter were bumped from a flight heading to a Colorado ski vacation in 2004, he lost his hotel deposit and didn't get their checked-in luggage and skis for four days.

He sued and won ($3,100) because the airline had not paid him the right amount and had failed to give him any written statement detailing his rights, as airlines are required to do by law.

Stone admitted that United mishandled the removal of an uncooperative passenger in Chicago earlier this month, but he also reminded all air travelers about the realities of a service so many of us take for granted.

Ever since 9/11, flight crews have been understandably strict about passengers following the rules, Stone said.

They need everyone on board to cooperate.

"If you become unruly, they can throw you off in an instant. Without recourse," Stone wrote. "If you refuse to follow a crew member's instruction, they can throw you off and send you to jail."

I was on a flight once across the Atlantic at a time when cigarette smoking had recently been banned on all flights, in all sections (hard to believe now there was a time when smoking was allowed anywhere on board). After the airplane was well out over the ocean, a well-dressed gent sitting nearby, lit up.

A stewardess was on him immediately. "Sir, smoking is not allowed. I must insist ..."

The man brushed her off, pointing to the ashtrays in the arm rests. "What are these for then?"

A few minutes later, the captain, a solidly built, military-looking fellow, appeared in the cabin. He leaned down and spoke in the man's ear very calmly and quietly.

The man visibly stiffened, put out his cigarette and sat erect, smokeless and polite the rest of the flight.

I always wondered what it was exactly the captain said to that guy. Whatever it was, it worked.