Know Your Options
Airline delays caused by bad weather, traffic control problems, and mechanical repairs are hard to predict. If your flight is canceled, most airlines will rebook you on the earliest flight possible to your destination, at no additional charge. If you're able to find a flight on another airline, ask the first airline to endorse your ticket to the new carrier. This could save you a fare increase, but there is no rule requiring them to do this.
Each airline has its own policies about what it will do for delayed passengers; there are no federal requirements. If your flight is delayed or canceled, ask the airline if it will pay for meals or a phone call. Contrary to what many people believe, airlines are not required to do so.
Under new federal rules, U.S. airlines operating domestic flights must allow passengers to deplane after a tarmac delay of three hours. The only exceptions allowed are for safety or security, or if air traffic control advises the pilot otherwise. Carriers are also required to provided adequate food and drinking water within two hours of being delayed on the tarmac; they must also maintain operable lavatories and, if necessary, provide medical attention.
There are other protections as well, such as prohibiting airlines from scheduling chronically delayed flights. For more information, search for Airline Passenger Protections on the Department of Transportation's website.
Selling more tickets than there are seats is not illegal. Most airlines overbook their flights to compensate for "no-shows." If there are more passengers than seats just before a plane is scheduled to depart, you could be "bumped" or left behind against your will. Whether you are bumped or not may depend on when you officially check-in for your flight, so try to arrive early. The U.S. Department of Transportation requires airlines to ask people to give up their seats voluntarily, in exchange for compensation. Airlines decide what to offer volunteers, such as money, a free trip, food or lodging.
Federal rules protect you if you are "bumped" on most flights within the United States and on outbound international flights. Passengers who are involuntarily bumped are protected under Federal Aviation Administration guidelines. If you volunteer to be bumped, your agreement with the airline that is not regulated and will depend on negotiating at the gate.
The airline must give you a written statement describing your rights, as well as the airline's boarding priority rules and criteria. If the airline is not able to get you to your final destination within one hour of your original arrival time, the airline must pay you an amount equal to 200% of your one-way fare, with a maximum of $650. To receive this payment, you must have a confirmed reservation. You must also meet the airline's deadlines for ticketing and check-in. An airline may offer you a free ticket on a future flight in place of a check, but you have the right to insist on a check.