United Airlines, the No. 2 U.S. carrier, has doubled a surcharge it added to tickets last month to offset high fuel costs, a spokesman said Friday.
The move effectively raises roundtrip fares by $10 and one-way tickets by $5. It applies to all U.S. states except Hawaii, spokesman Jeff Kovick said.
Airlines have struggled to keep pace with increasing fuel costs, which have risen along with the price of crude oil in recent months. Fuel represents one of the airlines' biggest expenses.
United has said every dollar increase in the price of crude oil increases its annual costs by approximately $65 million.
The increase is the 11th the industry has attempted since Labor Day weekend, said Rick Seaney, chief executive of FareCompare.com, a Web site the tracks airfares. Many of those increases were quickly matched by other airlines, but stiff competition has kept some of the increases from sticking over the long term.
Although the holiday season is one of the year's busiest travel periods, it is actually a slow time of year for ticket purchases, and several carriers have been offering sale prices on tickets for travel in January and February, Seaney said.
"I don't think I've ever seen an increase around Christmas," he said.
Jet fuel costs have increased, but crude prices have actually backed off from the record levels seen late last month, when traders pushed the price of oil near $100 a barrel.
