US Airways warned this week that unless it were able to make a profit soon it could "hinder our ability ... to sustain or expand our business."

"We do not expect our revenues to increase significantly until general economic conditions improve, and we expect the threat of further terrorist attacks and continued instability in the Middle East to continue to negatively impact our costs and revenues in the near term," the company said.

The grim forecast was included in a statement that the carrier filed with the Securities & Exchange Commission registering for resale 39.3 million shares of US Airways Class A common stock. The shares have been or are about to be issued to the Retirement Systems of Alabama, the Air Transportation Stabilization Board, General Electric Capital Corp. and Bank of America. Each of the entities acquired a significant stake in the company after it emerged from Chapter 11 bankruptcy protection in April in exchange for providing cash, loan guarantees or jet aircraft financing to the reorganized airline.

For example, the Retirement Systems invested $240 million in exchange for a 36.2 percent stake in the company. It also gained control of eight of the 15 seats on the reorganized airline's board of directors. The Air Transportation Stabilization Board acquired a 10 percent stake for providing $900 million in federal loan guarantees.

In the stock registration statement, US Airways also said it had filed an application with Nasdaq to be listed on that national stock exchange so that the investors will be able to publicly sell their shares.

Companies registering stock with the SEC are required to list the risks that potential investors might face if they buy shares in the company. While many of the risks facing US Airways have been reported, their recitation in the company's SEC filing indicate the difficulties that the airline faces, despite its successful emergence from Chapter 11.

Given the weakness in the airline industry, the company may not be able to "consistently achieve or sustain positive cash flow from operations and comply with all requirements of our debt repayments."

US Airways said cost reductions it had coaxed from lessors and labor -- totaling about $2 billion annually -- might not be enough "to effectively counteract" decreasing revenues and continued increasing costs.

The company noted that it was highly leveraged and had significant debt obligations. "Substantially all our aircraft and engines are subject to liens securing indebtedness," the carrier said.

A key element in the airline's plan to make a profit has been its plans to deploy hundreds of regional jets on its short-haul routes. But the carrier warned, "We may not be able to meet our commitments to purchase flight equipment, which could result in penalties and impair our ability to execute our regional jet business plan."

Such an eventuality could partially determine whether US Airways follows through on its plans to make Pittsburgh International Airport a hub for MidAtlantic regional jet division, provided the company and Allegheny County officials can reach an agreement on the terms of a new airport lease.

Should those negotiations fail, the airline said, it might "discontinue or reduce our operations at Pittsburgh, which wold require us to deploy those assets [regional jets and mainline aircraft]" elsewhere.

Although US Airways has filed the registration statement, the Retirement Systems and other "selling stockholders" won't be able to sell their securities until the registration statement becomes effective. When the SEC declares the registration statement effective, the holders of the shares will be able to sell them through public or private transactions at prevailing markets prices. US Airways will not receive any of the proceeds from the stock sales, the company said.

The company set a value on the stock of about $241 million, or $6.13 per share.

In the SEC filing, the carrier also said it didn't expect to pay out any cash dividends "in the foreseeable future."