Or, the filing could have no impact on ridership, could make labor even more resistant to concessions and could mean further inroads into valuable airports such as Washington's Reagan National and New York's LaGuardia by the low-cost carriers that already have helped push carriers such as Delta to the brink, experts and analysts say.

"On the surface, it could be positive, but long-term, Delta will only be able to get their share of filling the void if it lowers its cost structure," said airline analyst Ray Neidl with New York-based Calyon Securities.

Arlington, Va.-based US Airways, the nation's seventh-largest airline, filed for Chapter 11 Sunday - the second time in three years the airline has gone to bankruptcy court.

Locally, the airline's regional unit, US Airways Express, operates 12 flights from Cincinnati/Northern Kentucky International Airport. None of those flights - to Charlotte, N.C., Philadelphia and Pittsburgh - has yet been affected.

Sunday's bankruptcy filing came after last-minute negotiations with US Airways' unions fell apart and a faction of the pilots union blocked a vote on a possible deal on concessions.

Earlier this week, company chief executive officer Gerald Grinstein told the New York Times, the Wall Street Journal and Reuters in separate interviews that the development could mean good and then bad news for Delta.

He said some passengers could choose to book airlines other than US Airways because of the bankruptcy, which could help Delta since its route structure overlaps its competitor's so extensively.

"And the fact that most people think this one will probably end in liquidation could really accelerate those book-offs," said Michael E. Levine, a former executive for several airlines.

But Neidl disagreed, saying that most passengers accept airline bankruptcies as a fact of life.

If US Airways folds

If US Airways doesn't survive over the long term - and only Continental has emerged from a second bankruptcy in the past 20 years - it could create a free-for-all for some of its assets.

Only low-cost competition Southwest and JetBlue can buy more gates and planes, said airline analyst Helane Becker of Benchmark Co. LLC.

"The Deltas and Americans of the world have no extra money to be buying stuff," she said.

Added Levine: "US Airways owns about 7 percent of the national market right now, and some of that would go to the low-cost carriers - and that is not good news for Delta."

One potential boon for Delta's local operation is US Airways closing its hub in Pittsburgh, which had competed for connecting traffic at Cincinnati/Northern Kentucky International.

Delta wants concessions

Experts say that Delta's ongoing labor issues could be affected, key since the airline is trying to get $1 billion annually worth of concessions from its pilot union. That union in turn has said it was willing to concede up to $700 million annually.

"The Delta pilots agreed a year ago that a pilot investment was necessary," spokeswoman Karen Miller said. "We've been trying to be part of the overall solution since then."

Analysts say the situation at US Airways sends some sort of message to unions elsewhere, but that like the other factors, it could be good news or bad news.

"Its hard to ignore all these pension plans getting canceled all over the place," Becker said. "That's why Delta has had this problem of so many pilots retiring early."

She pointed out that it didn't take long after the US Airways announcement for the Delta pilots to agree to talks on early retirements. Delta said the issue could send it into Chapter 11 if not settled by the end of this month.

But others say that unions at other airlines could see the situation as another sign that all their concessions in the past were for naught - and that they shouldn't give any more.

"They are enormously frustrated at all the givebacks and no sign that they are working," Levine said.

E-mail jpilcher@enquirer.com