American Airlines parent AMR Corp , which is planning to merge with US Airways Group , has asked a judge for another extension of its exclusive period to file a plan to exit bankruptcy.

The carrier and its unsecured creditors committee asked the U.S. Bankruptcy Court on Wednesday to extend the time during which creditors cannot pursue their own restructuring plans for the airline to May 29. Currently, American has until April 15 to file its reorganization plan.

American and US Airways announced their plan to combine last month in an $11 billion deal that would form the world's biggest airline .

"The requested extensions are necessary in order to formulate, negotiate, and propose a Chapter 11 plan that implements the Merger," the carrier's filing said.

The American-US Airways deal has long been telegraphed and is supported by creditors.

The U.S. Justice Department requested additional details on the merger plan on March 4, a common occurrence in antitrust reviews of deals. The carriers expect the merger to close in the third quarter.

AMR filed for Chapter 11 protection in November 2011, citing high labor costs.