ATA Hldgs, Southwest Agree To Extend Ch 11 Plan Deadline Wednesday June 1, 5:29 PM EDT WASHINGTON (Dow Jones)-- ATA Holdings Corp. (ATAHQ) said Wednesday in a regulatory filing that it has worked out an agreement that extends by three months, to Dec. 31, the air carrier's deadline to file a Chapter 11 plan of reorganization. The company, which has been operating under bankruptcy protection since October 2004, said it reached an agreement with Southwest Airlines Co. (LUV), the provider of its debtor-in-possession loan, to extend the due date for the plan from its original deadline of Sept. 30. ATA said the changes were also approved by the Air Transportation Stabilization Board and the company's official committee of unsecured creditors. The company is the 10th-largest U.S. air carrier based on revenue passenger miles. -By Marc Hopkins Roger EWROPS