FORT WORTH, Texas (AP) -- American Airlines' parent AMR Corp. plans to raise $726 million and might seek an extra $232 million by issuing debt backed by 43 airplanes. AMR disclosed the offering Tuesday in papers filed with the Securities and Exchange Commission. Concern has grown recently about continuing losses and high debt at AMR. It was the only major U.S. airline company to lose money in 2010 and is expected to lose more in 2011 and 2012. The company burned through $1.1 billion in cash in the 12 months that ended June 30 and expects to have $4.7 billion in unrestricted cash left by Sept. 30. Moody's Investors Service, which lowered its outlook on AMR to "negative" last week, gave a "Baa3" rating to the pass-through certificates on Tuesday. J.P. Morgan said a successful offering is critical for the company to manage its way through the winter, a slow period for airlines. Speculation that AMR may seek bankruptcy protection “weighs on the entire sector, along with, of course, the natural market fear of a recession and the potential impact from an economic slowdown on an improved but still vulnerable sector,” the JPMorgan analysts wrote. “We remain in the minority camp that AMR will continue to tread water and avoid an in-court restructuring.” "The bottom line is that this deal makes us feel better about the AMR near-term credit story," J.P. Morgan analysts said. The certificates will be backed by Boeing 737, 757 and 777 aircraft with a combined appraised value of $1.59 billion, AMR said. The 757s and 777s are used heavily on American's international routes while the 737 is replacing McDonnell Douglas MD-80-series planes on domestic routes.