The parent company of American Airlines filed for bankruptcy protection Tuesday, seeking relief from crushing debt caused by high fuel prices and expensive labor contracts that its competitors shed years ago.

The company also replaced its CEO, and the incoming leader said American would probably cut its flight schedule "modestly" while it reorganizes. He did not give specifics. American said its frequent-flier program would be unaffected.

AMR Corp., which owns American, was the only major U.S. airline company that did not file for bankruptcy protection after the Sept. 11 attacks, which caused a deep slump in the industry.

Bankruptcy filings allowed American's competitors to shed costly labor contracts, unburden themselves of debt and start making money again. American was stuck with higher costs, and had to match its competitors' lower fares or lose money.

Other airlines also grew by pursuing acquisitions and expanding overseas. American was the biggest airline in the world in 2008, but has been surpassed by United, which combined with Continental, and Delta, which combined with Northwest.