WASHINGTON — The government is opening some military airspace to ease airline congestion over Thanksgiving and Christmas, though the effort is likely to have only limited results. And if the weather's bad, all bets are off.

President George W. Bush announced Tuesday that he's expanding the Thanksgiving express lanes this year to include military air corridors in the Midwest, the Southwest and the West Coast. That's in addition to the East Coast corridors, which were also freed up for holiday traffic last year.

The military uses the space for exercises, but often makes some available to commercial planes on an ad hoc basis.

Approximately 24 million passengers are expected to fly over the 12 days around the Thanksgiving holiday this year, said David Castelveter, a spokesman for the Air Transport Association, which represents the airline industry. That's about 10 percent fewer than last year, but airlines also have removed about 10 percent of their capacity from the system, meaning planes will be just as crowded. Castelveter said airplanes will be about 90 percent full at peak travel times and will be 100 percent full in key markets.

Making highways in the sky that are normally restricted to the military open to commercial airliners may get planes from one airport to another faster, but they'll still have to contend with bottlenecks at the nation's busier airports when they arrive.

Doug Church, a spokesman for the air traffic controllers union, said one result of airplanes arriving faster could be more planes circling busy airports and running low on fuel.

"Our point is that they don't have a plan to get them on the ground any faster," Church said. "This plan does nothing to relieve the congestion at the airports that are the traditional hotspots."

Story continues below

Transportation Department spokesman Brian Turmail said that by signaling to airlines in advance that the military corridors will be available, they will be able to consider these fast lanes in their flight plans to avoid unnecessary circling.

Tim Wagner, a spokesman for American Airlines, said the opening of military air space on the East Coast helped last year, especially around New York.

"Every little bit helps," Wagner said.

Castelveter said that some airliners may be able to get off the ground faster if there's an extra corridor to send them to, and that added corridors can also speed up planes to less congested airports, where they don't have to wait.

But he also acknowledged: "If you do all of these things and you get hit by bad weather, you're still going to have delays."

The National Weather Service says New York and New England should be wetter and colder than normal Thanksgiving week, and much of the rest of the East Coast and Southeast will be cold but dry. Northern California will be wetter than usual, and the rest of the nation will be normal or warmer and drier.

Bush also announced other steps to ease holiday air travel. He said his administration was working with the Federal Aviation Administration, the Transportation Security Administration and the airlines to make more staff available to speed check-ins and boarding.

The president also said new regulations that raise the amount airlines must pay to travelers for lost bags and for failing to notify passengers about hidden fees will be in place in time for the Christmas travel crush. Another recently implemented rule requires airlines to pay higher bump fees to passengers when they are ticketed buttravelers wind up without a seat.

Bush noted his administration's work to fix a main source of flight delays: problems at the three major New York City-area airports. The government says two out of three flights delayed 15 minutes or more were due to cascading backups beginning at John F. Kennedy, LaGuardia or Newark-Liberty.

Consumer advocates worry about another wrinkle this year _ that more passengers may be left standing at the gate.

Airlines trimmed their schedules about 10 percent this fall, and the industry is predicting many flights will be full or almost full. Airline overbooking could wind up increasing the number passengers who are bumped and leaving them with fewer options for getting another flight, said Kate Hanni of the Coalition for an Airline Passengers Bill of Rights.

There could be a lot of people sleeping overnight in "cot cities in Chicago," said Hanni, who founded the coalition after enduring a nine-hour tarmac delay on an American Airlines flight diverted to Austin, Texas, in December 2006.

But Castelveter said there is no obvious alternative.

"I'd like to know what she proposes. Fly empty airplanes?" Castelveter said. Airlines monitor bookings closely to try to make sure each plane goes out full, but they try to overbook only enough passengers to account for no-shows, he said.

___

Associated Press writer David Koenig in Dallas contributed to this report.