United Airlines hikes fares by up to $10 per round trip

A United Airlines airplane is unloaded after arriving at Newark Liberty International Airport in Newark, New Jeresy, June 18, 2011. A United Airlines computer problem caused system wide cancellations Friday evening forcing passengers to be stranded across the U.S. on Saturday. REUTERS/Gary Hershorn (UNITED STATES - Tags: TRANSPORT BUSINESS SCI TECH) (Reuters)

United Airlines is raising fares within the U.S. by up to $10 per round trip, the industry's first attempt at boosting prices in three months.

United said Friday that it raised prices by between $4 and $10 per round trip.

Fare increases don't always stick. United could be forced to roll back the increase if other airlines don't match it in the next few days.

"Historically, a coin flip determines whether a hike attempt broadly sticks," said Rick Seaney, CEO of FareCompare.com. He said United's increase was the seventh attempt by U.S. airlines to raise prices this year – three have stuck while four were rolled back.

Airlines were more aggressive about raising prices last year and early this year as jet-fuel costs soared. They grew cautious as the economy weakened in the second quarter, and they were under less pressure to raise prices because fuel costs eased starting in April.

The last successful broad U.S. fare increase was in late March.

Southwest Airlines Executive Vice President Robert E. Jordan took note Thursday of the industry's newfound hesitance to raise prices.

"The second quarter was the first time in a long time ... where we had no domestic fare increases as an industry that stuck," Jordan said. "It just gives you a little view into how the industry is thinking about pricing power."