Two more airlines and more than $45 billion of debt are under the supervision of a bankruptcy court Thursday after Delta ( DAL ) and Northwest undefined filed Chapter 11 petitions amid a storm of price and labor pressures. The two carriers, stung by surging fuel prices and competitive threats from low-cost carriers, made filings late Wednesday in the U.S. Bankruptcy Court for the Southern District of New York. Both airlines aim to conduct something approaching business as usual following the actions, which were preceded by desperate measures to align costs with the post-9/11 travel environment. "Delta is open for business as usual and will continue normal operations throughout the reorganization process," said Delta CEO Gerald Grinstein in a news release announcing the bankruptcy filing. "Our customers can be confident that they remain our number one priority and that their travel plans and SkyMiles are secure."