As Predicted Airfares going up this year

In the first effort to boost fares this year United States airlines have increased prices on long domestic trips by as much as $20 round trip.

Last year, after a two-year lull, airlines made 22 attempts to increase fares, nine of them successful.

This time, Delta made the first move, increasing fares by $10 each way on routes longer than 1,500 miles on Wednesday. United-Continental Airlines, American Airlines,and US Airways confirmed on Thursday that they matched the increase on their longer-haul routes.Low-cost carriers Southwest-AirTran and Frontier Airlines also matched the hikes, according to FareCompare.com, which tracks fares.Southwest increased fares by $10 one-way on routes longer than 1,500 miles."We're still really battling high fuel prices," says Southwest spokeswoman Katie McDonald. "Any kind of increase we take is specifically to combat the high cost of fuel."

Fare increases often don't last because carriers don't want to price themselves too high above their competitors. But a low-cost carrier matching is a good indicator that it will stick.The airlines were most successful at raising fares in the first half of last year after cutting back on flights, which led to increased demand for seats. Airline mergers have also helped reduce competition.But Southwest blocked the last five attempts at increasing fares by refusing to go along, according to research by analysts at JPMorgan. Up until this week, Southwest had not had an across-the-board fare hike since mid-October, though it had made a few small, tactical increases in unique fare categories, the analysts say.

"In our view — at least for now — we would disagree with any suggestion that Southwest management (or its pricing department) is otherwise asleep at the switch. On the contrary, the opposite increasingly appears to be true," the analysts wrote on Thursday.Rick Seaney, chief executive officer at FareCompare.com, says he expects domestic carriers to continue to try boosting prices every couple of weeks in the first half of the year with limited success.

"I think the main reason is that airlines have no choice but to fill up historically empty middle seats with folks who have much thinner wallets than they did before the recent recession," he says.