U.S. airlines in 2007 bumped passengers against their will from ticketed flights at the highest rate in 11 years. The nation's 18 largest airlines denied boarding to 63,878 passengers, or 1.12 per 10,000 passengers, a recently released U.S. Department of Transportation report shows.

In a practice widely loathed by consumers, most airlines sell more tickets than available seats on flights to offset a projected number of no-show passengers. Airlines say the practice helps them keep fares low by letting them fill more seats.

But fuller-than-normal planes and frequent delays in 2007 gave airlines less flexibility in finding convenient alternatives for passengers on overbooked flights, said David Castelveter, of the Air Transport Association trade group.

Airlines generally are able to minimize problems at the gate by offering inducements — a free trip or a credit voucher — to travelers willing to change plans. According to DOT, most people who got bumped from their ticketed flights last year agreed to the switch.

In 2007, 621,717 people switched to other flights voluntarily.

Frequent flier Jay Hibbard of Portland, Maine, said he never takes the bait when airlines ask for volunteers. "If you give up a seat, there is no telling when you'd actually get where you need to be," he said.

Delta Air Lines had the highest rate among the big traditional airlines in 2007, bumping 2.47 per 10,000 passengers. Betsy Talton, a Delta spokeswoman, said the rate is "higher than we'd like," and that the carrier has formed a team to find ways to reduce it.

Continental Airlines last year had the second-highest rate among the large traditional airlines, 1.43 per 10,000 passengers. David Messing, a Continental spokesman, said the rate reflects the carrier's growing emphasis on international routes, which typically involve fewer alternatives for re-routing passengers.

The DOT is considering overhauling its rules governing involuntary bumping.

Among other changes, a proposal would double the maximum compensation that airlines are required to pay.

If approved, airlines would have to give up to $400 to passengers who reach their destination within two hours of schedule on domestic flights, or four hours for international flights.

Airlines would pay up to $800 for longer delays.