US Airways Group, the No. 6 U.S. airline, Thursday reported a fourth-quarter net loss of $1 billion, amid a battering by a weak economy, low-cost rivals and a travel slump after last year's attacks on the United States.

US Airways, also hurt by the temporary shutdown of its Reagan National Airport hub following the Sept. 11 attacks, reported a net loss of $1.01 billion, or $14.89 per share.

The airline said quarterly operating revenues plunged more than 33 percent to $1.57 billion from $2.35 billion a year earlier.

Excluding charges and other unusual items, US Airways lost $552 million, or $8.16 per share, compared with a year-earlier loss of $89 million, or $1.33 cents per share.

Wall Street analysts expected a loss of $6.23 to $8.30 per share, with an average estimate of $7.54, according to research firm Thomson Financial/First Call.

The airline said it ended the year with $1.08 billion in cash.

Heavily reliant on its East Coast routes, US Airways has struggled more than other airlines to counter weaker demand, especially with the short-term closure of Reagan National Airport just outside of Washington, D.C.

US Airways shares have plummeted nearly 90 percent from a year ago and the stock is off about 50 percent since the Sept. 11 attacks, which crippled the nation's air system and sharply curtailed air travel demand.

The broad benchmark American Stock Exchange Airline Index, has fallen more than 43 percent over the last year.

Amid warnings of potential bankruptcies, Congress enacted a $15 billion aid package for the airline industry in the wake of the Sept. 11 attacks.

But US Airways has insisted it does not intend to apply for the loan portion of that package. Still, aviation experts believe the carrier is one of those most at risk for bankruptcy because of its high debt-to-capital ratio and high labor costs.

Last year US Airways unveiled a restructuring plan to bolster its regional jet fleet and retool its mainline fleet to cut costs and stave off competition on major routes.

The restructuring came after antitrust regulators scuttled a $4.3 billion bid by UAL Corp.'s United Airlines to acquire US Airways.