NEW YORK - The U.S. trustee in the Chapter 11 bankruptcy of AMR Corp., the parent company of American Airlines Inc., on March 25 filed a sur-reply brief in the U.S. Bankruptcy Court for the Southern District of New York objecting to the proposed $11 billion merger of AMR and US Airways Group Inc. (In Re: AMR Corporation, No. 11-15463, Chapter 11, S.D. N.Y. Bkcy.).