NEW YORK - U.S. airlines raised fares for a second time in two weeks, a strong signal that the industry is nearing a bottom on ticket prices, according to, a site that compares prices for flights.

AMR Corp's American Airlines hiked prices between $5 and $10 for a one-way ticket for a large number of its U.S. routes on Wednesday. Later that day, UAL Corp's United Airlines matched those increases on many of its own U.S. flights.

The increases are an attempt by airlines to lift prices ahead of a key summer season, typically a strong period for the airline industry, said Rick Seaney, chief executive of

Until about three or four weeks ago, you saw almost continuous airfare sales, said Seaney. Now the sales we do see are Tuesday, Wednesday, Saturday sales, off-peak sales instead of discount.

The increases also suggest some business travel is coming back, a welcome change for the airline industry, Seaney added. Fares have suffered sharply this year due in part to fewer travelers paying for business-class seats, which cost between 2.5 to 3 times more than a coach-class ticket.

If there is another (fare hike) in a couple of weeks, we'll know for sure, Seaney said.

Sluggish consumer and corporate spending has forced airlines to drop fares to stimulate demand. The industry has also been hurt by oil prices, which have doubled since early February.

Still, in recent weeks, the pace of discounting has slowed and there are signs of stabilization. Major legacy carriers and low-cost carrier Southwest Airlines boosted fares on U.S. flights two weeks ago for the first time this year.

On Thursday, data from the International Air Transport Association showed May passenger traffic slumped 9.3 percent. The improvement appeared to show the decline in traffic was leveling off, although not improving.

We may have hit a bottom, but we are a long way from recovery, said Giovanni Bisignani, IATA's CEO, in a statement.

(Reporting by Deepa Seetharaman, editing by Dave Zimmerman)