Getting bumped from an oversold airline fight against your will is one of the most aggravating experiences in the frustration-filled world of airline travel. Thus, airlines are federally required to compensate travelers subjected to such a predicament and the mandated payout is about to go up.

Effective Tuesday, airline travelers involuntarily bumped from a flight were eligible for double the amount they were previously, up to $1,300 depending on the value of their ticket and the length of time they have to wait for another flight.

Getting involuntarily bumped from a flight is very rare. Fewer than one passenger in 10,000 on the largest U.S. airlines are affected on average, according to the U.S. Bureau of Transportation Statistics.

But when it does happen, "It can be really devastating," said Kate Hanni, executive director of FlyersRights.org. Travelers going on their honeymoons or headed to funerals may come to the airport to find out they don’t have a seat, Hanni said. "People believe they have a seat when they buy a seat. They have no reason to believe otherwise," she said.

Bumping is in part due to airlines' practice of overbooking flights to make up for passengers who don't show up for a flight.

When seats go out empty, "Over time, it's a significant amount of revenue for an airline," said Southwest Airlines director of revenue management Jeff Houston. So airlines generally look at how many no-shows a flight historically generates and overbook slightly.

"Given that the costs of a flight are considerable, particularly with what we're seeing with high fuel prices these days, being able to cover these costs helps us continue to operate," said Delta Air Lines spokesman Trebor Banstetter.

Involuntary bumping -- or denied boarding, as it is called in airline lingo -- is different from volunteering to take a later flight in exchange for vouchers or similar compensation from the airline. Involuntary denied boarding typically comes after the airline has exhausted its list of volunteers and still has too many passengers to fit on the plane.

Atlanta-based Delta had 1,419 involuntary denied boardings in the first six months of the year, or 0.29 per 10,000 passengers. When it comes to keeping involuntary bumping to a minimum, Delta ranked third among the 16 largest U.S. airlines.

Southwest, meanwhile, had 4,269 involuntary denied boardings in the same period, or 0.78 per 10,000 passengers. Southwest ranked seventh. Southwest acquired AirTran Airways and will replace AirTran service in Atlanta and elsewhere with its own.

Delta credits its low bumping rate in part to a system it started late last year which involves taking bids from passengers checking in online or at an airport kiosk who are willing to volunteer to take a later flight.

By accumulating more data on flights over the years, "We get better and better at doing this over time," Banstetter said. He said Delta is also more aggressive in contacting passengers in advance when their flight is switched to a smaller plane and they must be rebooked to different flights.

Southwest touts its lack of change fees in its advertising, but that also contributes to a higher rate of bumped passengers because the policy produces a slightly higher no-show factor, according to Houston.

Houston said Southwest's philosophy is that charging change fees is a larger negative to customers than a higher overbooking rate.

Southwest, a low-cost carrier battling higher costs, is seeking ways to increase revenue, so it has been trying to fill planes more than before, leading to more bumped passengers.

And Southwest's attempts to gain more business travelers has also added more uncertainty, because business travelers are the most likely to miss a flight and take another one when meeting plans change. They are also more likely to buy higher-priced refundable fares with more flexibility.

Still, Southwest has improved its performance, going from 8,992 involuntary denied boardings in the first half of 2010 to the 4,269 in the first half of 2011.

"It's just a lot harder to find someplace to put somebody now and as a result, you have to manage the oversales a bit more conservatively," Houston said.

Under the new rules

  • Involuntarily bumped passengers are entitled to cash compensation equal to double the one-way value of their tickets, up to $650, if the airline was able to get them to their destination within a short period of time (within one to two hours of their originally scheduled arrival time for domestic flights and one to four hours for international flights).
  • Passengers delayed for a lengthy period of time (more than two hours after their originally scheduled arrival time for domestic flights and 4 hours for international flights) are entitled to four times the value of the one-way price of their tickets, up to $1,300.
  • Inflation adjustments will be made to the compensation limits every two years.

Source: U.S. Department of Transportation

Other new passenger protections that took effect Tuesday

  • Airlines are required to refund any fee for carrying a bag if the bag is lost.
  • Airlines must prominently disclose all optional fees on their websites, including fees for baggage, meals, canceling or changing reservations, or advanced or upgraded seating.
  • The existing federal ban on lengthy tarmac delays is expanded to cover the international flights of foreign airlines at U.S. airports. There is now a hard four-hour time limit on tarmac delays for all international flights at U.S. airports.
  • The three-hour tarmac delay limit for domestic flights at large-hub and medium-hub airports is extended to flights at small-hub and non-hub airports as well. Exceptions to the tarmac delay time limits are allowed for safety, security or air traffic control-related reasons. Carriers must ensure that passengers stuck on the tarmac are given adequate food and water after two hours, working lavatories and any necessary medical treatment.

Source: U.S. Department of Transportation