Frustration for passengers continues to mount as American Airlines grounded more planes on Friday.

The Associated Press reported that as many as 250,000 travelers have been affected by American's cancellations this week alone.

Section: Holidays

American has given $500 travel vouchers to an unspecified number of inconvenienced passengers and is putting some travelers up in hotels.

Contrary to popular belief, airlines are not required to compensate passengers whose flights are delayed or canceled.

Compensation is required by law only when you are "bumped" from a flight that is oversold. Airlines almost always refuse to pay passengers for financial losses resulting from a delayed flight.

Overbooking is not illegal, and most airlines overbook their scheduled flights to a certain extent in order to compensate for "no-shows." Passengers are sometimes left behind or "bumped" as a result. When an oversale occurs, the Department of Transportation requires airlines to ask people who aren't in a hurry to give up their seats voluntarily, in exchange for compensation. Those passengers bumped against their will are, with a few exceptions, entitled to compensation.

DOT requires each airline to give all passengers who are bumped involuntarily a written statement describing their rights and explaining how the carrier decides who gets on an oversold flight and who doesn't. Those travelers who don't get to fly are frequently entitled to an on-the-spot payment of denied boarding compensation. The amount depends on the price of their ticket and the length of the delay:

• If you are bumped involuntarily and the airline arranges substitute transportation that is scheduled to get you to your final destination (including later connections) within one hour of your original scheduled arrival time, there is no compensation.
• If the airline arranges substitute transportation that is scheduled to arrive at your destination between one and two hours after your original arrival time (between one and four hours on international flights), the airline must pay you an amount equal to your one-way fare to your final destination, with a $200 maximum.
• If the substitute transportation is scheduled to get you to your destination more than two hours later (four hours internationally), or if the airline does not make any substitute travel arrangements for you, the compensation doubles (200 percent of your fare, $400 maximum).
• You always get to keep your original ticket and use it on another flight. If you choose to make your own arrangements, you can request an "involuntary refund" for the ticket for the flight you were bumped from. The denied boarding compensation is essentially a payment for your inconvenience.
There are a few conditions and exceptions:
• To be eligible for compensation, you must have a confirmed reservation. An "OK" in the status box of your ticket qualifies you in this regard even if the airline can't find your reservation in the computer, as long as you didn't cancel your reservation or miss a reconfirmation deadline.
• You must meet the airline's deadline for buying your ticket. Discount tickets must usually be purchased within a certain number of days after the reservation was made. Other tickets normally have to be picked up no later than 30 minutes before the flight.

Complaints about airline service may be registered with DOT's Aviation Consumer Protection Division. To send a complaint, comment or inquiry electronically, use their Web form at DOT.

You may call the ACPD 24 hours a day at 202-366-2220 (TTY 202-366-0511) to record your complaint.

Or send a letter to:
Aviation Consumer Protection Division, C-75
U.S. Department of Transportation
1200 New Jersey Ave, S.E.
Washington, D.C. 20590