With two of the nation's big carmakers having filed for bankruptcy reorganization, can airlines be next?

No - not yet.

A pack of major U.S. airlines went through Chapter 11 bankruptcies after the Sept. 11 terror attacks.

And that puts them in better shape, for now, to weather the economic downturn, experts say.

Earlier in this decade, Delta, United, Northwest, Hawaiian and US Airways Group all went through bankruptcy protection - twice for US Airways, in 2002 and 2004.

Top carriers used the court process to reduce debt, slash labor costs, and dump traditional pension plans.

Aloha and American Trans Air airlines sought bankruptcy restructuring, and ultimately went out of business.

American and Continental airlines averted bankruptcy but won wage and benefit concessions from union employees.

"Airlines have gone through this boom-and-bust cycle so many times in the past 30 years that they recognized what they had to do, and so have done it," said airline analyst Helane Becker with Jesup & Lamont.

Many issues automakers and airlines face are the same - pension and infrastructure costs, and retiree and health-care issues. But the magnitude of the cash outflow for auto companies was "far worse" than for airlines, said William Warlick, a credit analyst for Fitch Ratings.

Car sales are cut in half this year, and U.S. manufacturers contend with fierce competition from foreign carmakers, including Toyota and Honda.

"Arguably the demand and revenue shock on the auto side was even greater" than for airlines, Warlick said. Until now, the auto industry has not been through bankruptcy reorganization.

General Motors Corp. and Chrysler L.L.C. were saddled with high labor costs, massive debt and hefty retiree and health-care obligations when they filed for court protection from their creditors. Chrysler emerged from bankruptcy last week.

"The auto industry has been in this precarious place for a long time, looking at foreign competition and lower-cost domestic competition," said aviation consultant Robert Mann. "Airlines have essentially been through this."

U.S. airlines took aggressive steps last summer when crude oil peaked at $147 a barrel. They trimmed seat capacity by swapping bigger planes for smaller ones, reduced flight frequencies, and eliminated unprofitable routes.

Airlines also cut thousands of jobs, grounded aircraft, and canceled or delayed orders for new planes.

But the outlook for airlines is increasingly uncertain.

High-fare business and first-class travel plummeted 22 percent in April from the year before. Jet fuel, one of airlines' biggest costs, has risen dramatically in the last few months.

"There's just a lot of volatility out there," said Mann of R.W. Mann & Co. "Certainly, the unemployment level in this country doesn't help."

To avoid Chapter 11 bankruptcy now, airlines have been raising cash, through sales of stock, mortgaging aircraft, and selling frequent flier miles to banks. "It's a real grab bag of finance that they have been doing," Mann said.

Warlick, of Fitch Ratings, said: "The concerns about liquidity, cash balances, and, importantly, access to capital markets are the primary concern of airlines looking ahead six to 12 months."

United, US Airways and American are the most vulnerable in cash reserves relative to revenue, access to credit markets, and available assets to support secured borrowing, Warlick said.

Continental, Delta, JetBlue are the next three most at risk, while low-fare carrier Southwest Airlines Co. has the best balance sheet. "But Southwest has revenue issues and is pulling down capacity just like everyone else." Warlick said. "It's an industrywide problem."

Airlines are responding by shrinking even more.

Delta said it would cut seat capacity by an additional 10 percent starting in September.

American said it will trim about 2 percent on mainline routes and 3.5 percent on its international network.

United said it is looking at additional capacity cuts for the fall.

Airlines also are cutting more jobs.

American said it would eliminate 1,600 jobs beginning in late August. Delta said it would "reassess" staffing and may trim payroll again.

US Airways wants 400 flight attendants to take voluntary furloughs, including 300 in Las Vegas and Phoenix, and 100 spread among Philadelphia, Charlotte, Boston, New York and Washington.

"If we have a recovery in 2010, the airline industry as we know it should survive," said Becker of Jesup & Lamont. "If I am wrong and recovery doesn't occur until 2011, then I'd say there are airlines out there that would be in financial difficulty."

Contact staff writer Linda Loyd at 215-854-2831 or lloyd@phillynews.com.