Airline passengers nationwide will find fewer and fuller flights this fall and winter as the nation's carriers continue to cut service to...

Airline passengers nationwide will find fewer and fuller flights this fall and winter as the nation’s carriers continue to cut service to combat rising fuel costs.

United Airlines, the nation’s No. 2 airline and the fourth-largest carrying passengers through Seattle-Tacoma International Airport, was the latest Wednesday to announce plans to slash domestic flights, cut jobs and ground gas-guzzling aircraft.

It’s not yet known how the cutbacks will affect its 46 daily departures from Sea-Tac. Destinations include Chicago, Denver, Portland, Jacksonville, San Antonio, Los Angeles, San Francisco, Spokane and Washington, D.C. United also has nonstops to Tokyo and to Frankfurt, Germany.

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“The impact (of flight cutbacks) as far as specific areas is still being determined,” a spokesman said.

But as other airlines look at eliminating unprofitable routes or shifting planes to areas where demand is high, smaller airports are expected to be hit harder than busier ones where demand and fares are high.

In many cases, major carriers have more than doubled or even tripled their cheapest U.S. fares from last summer’s fares, Tom Parsons, chief executive of the discount travel site, found when looking at the lowest fares for nonstop travel in July.

Parsons said where major carriers offer nonstop flights and low-fare competitors offer only one-stop service, fares are up to 365 percent higher than a year ago.

Seattle, so far, has been largely unaffected by any major cuts in service, although that could change as high summer demand begins to fade.

“As of right now, we’re not aware of any cuts here at Sea-Tac,” said airport spokeswoman Terri-Ann Betancourt. “The planes are leaving full, and we’re experiencing really high traffic.”

Chicago-based United said it will cut domestic capacity by 17 to 18 percent in 2009, while also scaling back international capacity by 4 to 5 percent.

Seattle-based Alaska Airlines, which along with its sister carrier, Horizon Air, handles nearly 50 percent of Sea-Tac’s domestic passengers and almost 40 percent of international traffic, announced last month that it will be ending nonstop service between Portland and Orlando and between San Francisco and Vancouver, B.C. It also will not return this winter to three destinations in Mexico from San Francisco.

Horizon will discontinue nonstop service between Spokane and Sacramento, and end service to Butte, Mont., as well as drop some flights between Seattle and Portland; Bend, Ore.; and Kelowna, B.C.

On the other hand, Alaska is adding flights to and from Seattle into the Bay Area; Maui and Kona, Hawaii; and Minneapolis.

“We’re shifting capacity around to where we can meet our customers’ demand,” said spokesman Paul McElroy.

A spokeswoman for Southwest Airlines, the third-largest Sea-Tac carrier in terms of domestic passenger traffic, said the discount carrier has no plans to trim service here or in Portland.

Passengers whose flights are dropped or changed will be notified, a United spokesman said.

The airline’s policy is to rebook passengers on another flight with United or another carrier, or offer refunds, depending on the situation.

McElroy said Alaska/Horizon would offer to refund the fare, reroute passengers or, if necessary, rebook on another airline at no extra charge.

United said it plans to ground its entire fleet of 94 Boeing 737s as well as six of the company’s 747s — its oldest and least fuel-efficient planes. It previously said it was going to mothball 30 of the jets.

It is also scrapping its coach-only “Ted” service and reconfiguring those planes to include first-class seats.

Officials said the “aggressive” moves are designed to the help the airline weather an “unprecedented fuel environment.” Crude-oil futures prices peaked at a record above $135 a barrel nearly two weeks ago and airline fuel prices have been rocketing higher as well.

American Airlines announced last month that it would cut workers and slash its domestic flight capacity by 11 to 12 percent in the fourth quarter, after the peak summer season is over.

The carrier was previously planning a 4.6 percent cut. It also said it would charge passengers $15 for the first checked bag.

Information from The Associated Press is included in this report.

Carol Pucci: 206-464-3701 or