American Airlines, United Airlines and Boeing added their names to a growing list of commercial aviation companies that are cutting workers, eliminating routes -- and hoping to avoid bankruptcy in the aftermath of last Tuesday's terrorist attacks.

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American Airlines, the nation's largest airline, put an end to days of rumors on Wednesday by announcing that it would lay off at least 20,000 employees. The layoff announcement had been expected since the beginning of the week.

AMR Corp., the parent company of American Airlines, said the cuts will be spread across American, Trans World Airlines and the American Eagle commuter line. The companies have 138,350 employees.

United Airlines, the nation's No. 2 airline, also came out on Wednesday with plans to cut about 20,000 jobs in the wake of the attacks. The cuts amount to about 20 percent of its work force of 100,000 people.

United has been harder hit by the disaster than other carriers. Not only were two of its flights involved, it relies more than others on revenue from business travel, which is expected to decline drastically. It announced a 20 percent schedule reduction last weekend, cutting its daily flights to about 1,900.

Late Tuesday, Boeing announced it was laying off up to 30,000 employees by the end of next year. 

The company will likely start handing out pink slips within three weeks, with layoffs to begin about two months later, he said. The layoffs, expected to be between 20,000 and 30,000, will be made across the board, he said. 

Roughly 93,000 people work for Boeing's commercial airline sector, much of which is centered on the company's former headquarters in Seattle. Boeing's corporate headquarters are now in Chicago.

Major airlines have announced more than 26,000 layoffs and say that figure could reach 100,000 in the coming weeks as a result of the grounding of flights following the Sept. 11 attacks and prospects for seriously reduced business in the coming months. Most carriers have scaled back schedules by 20 percent in an effort to remain solvent. 

Federal Aid Package

All those announcements come as the commercial aviation industry is making a hard push for a federal aid package, saying its very survival is at stake.

The major U.S. carriers are seeking $17.5 billion in assistance from the U.S. government, down from $24 billion sought earlier in the week, the group's trade organization said earlier Wednesday. 

The Bush administration is in favor of quick action to prop up the industry, while making clear that the aid should be directly related to losses from the attacks and should not subsidize past bad business practices by the industry. 

On Tuesday, leaders of major airlines met with Transportation Secretary Norman Y. Mineta and sought assurances that the Bush administration is committed to the industry's financial survival. 

Mineta said Tuesday that he hopes to have a U.S. airline bailout package ready for Congress by early next week.

The House could pass legislation providing at least $15 billion in grants and credits to the industry.

Cash aid was not the only thing on the airlines' shopping list. Delta Air Lines Inc. chairman Leo Mullin said that, while the airlines were not seeking protection from lawsuits filed by the families of passengers on the doomed aircraft, they needed legislation making clear the airlines were not liable for damage to people and property on the ground. 

``Such legislation would prevent the terrorists who perpetrated this tragedy from claiming still more victims, namely the airlines and manufacturers,'' Mullin said.

Layoffs and Bankruptcy

America West Holdings Corp. said Wednesday it was one of several airlines that may be forced to file for bankruptcy unless Congress quickly provides financial aid to the industry. 

``... several airlines are anxiously watching these proceedings and if something can't be done would very likely be forced to file bankruptcy in a number of days,'' America West Chief Executive Douglas Parker told a House Transportation Committee hearing. ``America West is one of those several airlines.'' 

The credit ratings of the three largest U.S. airlines were downgraded by Moody's Investors Service, which usually translates into higher borrowing costs for corporations. American Airlines and Delta were dropped to junk bond status and United Airlines debt fell four notches deeper into junk. 

Moody's downgrades affecting about $38.8 billion of debt, 

Standard & Poor's, another credit rating agency, is reviewing all large U.S. airlines' ratings for downgrades. 

US Airways Group told shareholders at its annual meeting on Wednesday that the nation's sixth-largest carrier had less than $1.2 billion in cash on hand. 

Industry analysts had estimated the airlines were losing $250 million to $300 million a day before they resume reduced flight schedules late last week. 

On Monday, U.S. Airways announced it would lay off 11,000 employees, or 24 percent of its work force, and drastically cut service. The company said it had no choice because the attacks had reduced passenger demand and prompted expensive new security requirements.

America West Airlines said it would cut about 2,000 jobs and reduce flights by about 20 percent.

Continental laid off 12,000 employees, or 21 percent of its work force, over the weekend.

National Airlines of Las Vegas announced Sunday it was cutting back its operations by 20 percent and laying off 300 workers, leaving it with 1,000 employees. Midway Airlines of North Carolina closed down last week while in the midst of reorganizing its financially troubled business, laying off 1,700 employees. 

Reuters and the Associated Press contributed to this report.