Arlington-based US Airways has 28,000 employees

It said the contract changes would be worth $38m (�21m) a month, and with other measures it hopes to save $200m.

It says this would see it into March, otherwise it may go bust by February.

The US's seventh largest airline filed for bankruptcy protection for the second time in two years this month, much to the anger of UK-based rivals.

The Arlington-based airline had been negotiating with its 28,000 staff to try to claw back more than half of a $1.5bn cost-savings plan proposed by the management.

Now, without new cash in the coming months, it warns it would have to shed staff and might be forced to liquidate after January.

'Cash crunch'

The airline, which has been trying to turn itself into a viable competitor for low-cost carriers, expects to lose $600m this year.

Revenues lost in recent weeks from Hurricanes Frances and Ivan, which hit Florida and the US Gulf Coast in recent weeks, were $20m.

"Waiting for a cash crunch to be right in front of us is simply too late, and if we were forced to implement interim relief at a later date, the pay cuts would be deeper and even more painful," said US Airways Chief Executive Bruce Lakefield.

"The debtors must immediately begin to transform or they will almost certainly fail," the company said in court papers.

'Long-term agreement'

The court papers detail a proposal for pay cuts of 23%, reduced pension benefits, and work rule changes.

The pilots' union has said it will oppose the court request, but that members understood savings had to be made.

Jack Stephan, a spokesman for the Air Line Pilots Association, said: "We're still committed to a long-term agreement."

US Airways was one of the quickest to deal with the dire straits in which the aviation industry found itself after the 9/11 attacks in 2001.