U.S. cargo airline Southern Air Inc. filed for bankruptcy protection today citing cutbacks in defense budget and U.S. troop reduction in Afghanistan, Reuters reported. The filing comes as the government's self-imposed year-end deadline approaches to agree on a plan to shrink the federal budget or trigger $600 billion in spending cuts and higher taxes. The Pentagon early this year outlined a 2013 budget plan to reduce spending by $487 billion over the next decade. Southern Air posted a revenue of about $428.2 million and a net loss of $159.8 million for the year ended July 31. The company had assets of about $206.9 million and liabilities of about $486.5 million as of that date. The Connecticut-based company, which operates a fleet of 11 Boeing Co aircraft, has about 611 full-time employees, according to its chapter 11 petition.