Northwest Says It Will Hike Fares 10% : Airlines: The move to increase domestic ticket prices catches analysts by surprise. The carrier launched a fare-cutting war just weeks ago.

After snapping up millions of half-price airline tickets earlier this month, travelers now face the prospect of sharply higher fares if Northwest Airlines gets its way.

The nation’s fourth-largest airline, which triggered the frenzied half-off fare sale, on Tuesday said it will hike domestic ticket prices by a surprisingly steep 10%.

None of the other major carriers rushed to match the Northwest fare increase, and some industry observers were skeptical of whether the higher prices would stick.

“By traditional standards, 10% is a very high fare increase,” said Donald S. Garvett, a pricing expert at Simat, Helliesen & Eichner, a New York-based airline industry consulting firm. “The likelihood of it sticking is likely very small.”

Northwest’s 10% increase will be applied to all ticket purchases beginning June 26.

“It will not give us a profitable year, but it will get us in the right direction,” Northwest spokesman Mark Abels said. “The (current) fare structure does not cover the cost of doing business.”

The new fares increase Northwest’s cheapest round-trip coach ticket between New York and Los Angeles from $380 to $418, and between Chicago and Dallas from $290 to $319.

In late May, Northwest touched off a costly fare war with a summer travel promotion that allowed an adult to fly free when accompanied by a child. American Airlines responded by cutting vacation fares by 50%, a move that was matched by the entire industry.

Greg Jones, a partner in the travel consulting practice of Towers Perrin in San Francisco, said the 10% increase would take advantage of interest generated by the previous fare cut.

“Given that the American (fare) initiative has done a good job of stimulating summer traffic, the opportunity now is to ride the coattails of that and generate revenues,” Jones said.

Airlines have had trouble raising fares this year in the face of the nation’s economic slump. After adopting a fare hike of 2% in January, the industry balked at raising fares another 2% a few weeks later. Unless other airlines match the 10% increase, Northwest would have little choice but to abandon the move or risk losing passengers to competitors.

But airlines appear to be in a better position now to raise fares in the middle of the peak summer travel season and after selling millions of seats during the half-off sale.

“They have a limited number of seats left through the summer months,” said Thomas Nulty, president of Associated Travel Management. “They will get as much as they can from those few seats.”