Alexandria, Va. ? US Airways, hard hit by slumping travel following the Sept. 11 terrorist attacks, filed for Chapter 11 bankruptcy Sunday the first major carrier to declare bankruptcy since the attacks put the industry in a tailspin.

US Airways said all of its flights are expected to continue without interruption. It had mentioned bankruptcy as a possibility after it lost $2.1 billion during 2001 and more than $500 million this year.

Although the airline didn’t lose any planes Sept. 11, its business was severely hurt when Reagan National Airport, the airline’s main hub, was shut down for three weeks and then reopened with only a limited schedule. The airline also laid off 11,000 workers shortly after the attacks.

The Arlington, Va.-based airline said it had received $500 million in private financing to keep operating while it reorganizes.

“US Airways will continue to operate while we complete our financial restructuring, and our customers should be confident that we will continue service to the more-than 200 communities in our network,” said US Airways president and chief executive David Siegel. He said the airline would seek a return to profitability and could emerge from bankruptcy by the first quarter of 2003.

The commercial aviation industry, which has lost a combined $1.4 billion this year, has been under pressure for the past 18 months because of a downturn in travel. The industry also has been hurt by higher security costs related to the terrorist attacks.

The airline, the nation’s seventh-largest and the 14th largest in the world, listed $7.81 billion in assets and $7.83 billion in liabilities in its petition, filed with the U.S. Bankruptcy Court for the Eastern District of Virginia. The court scheduled a hearing for today.

US Airways has been trying to wring $950 million in cost cuts from its 40,000 employees as part of a restructuring plan that was designed to stave off bankruptcy. Last week, it reached agreements with unions representing its pilots and flight attendants that called for wage and benefits cuts in order to keep the airline operating.

The International Association of Machinists and Aerospace Workers said it would submit the company’s proposal to a vote.

“Our members will not give up on US Airways, and neither should anyone else,” Robert Roach Jr., general vice president of the union said after the bankruptcy filing. “We believe US Airways can successfully restructure while it continues to serve the traveling public and provide employment for our members.”

The airline said its interim financing will come from a group led by Credit Suisse First Boston and Bank of America Corp., with participation from Texas Pacific Group, which has agreed to provide $200 million in equity when the carrier emerges from bankruptcy.

The much-smaller Vanguard Airlines filed for bankruptcy last month, citing similar problems after Sept. 11.