CHICAGO (Reuters) - Goldman Sachs said Monday analyst Glenn Engel widened his loss estimates for American Airlines parent AMR Corp. and recommended a swap into shares of rival UAL Corp , parent of United Airlines. Engel rated Texas based AMR a market performer and Chicago-based UAL a trading buy. "AMR has yet to achieve higher revenue per aircraft on its purchased TWA assets, and the world's largest carrier's unit revenue comparisons continue to lag the industry," Engel said in a research note. "In its 8K (regulatory filing), management warned that losses would not narrow as quickly in 2Q as they did in 1Q; six weeks ago, management predicted that 2Q losses would narrow by the same magnitude." Engel now sees a second-quarter loss of $2.45 per share for AMR, compared with a consensus loss estimate of $2.05 and wider than his previous estimated loss of $1.80. For the 2002 year, he widened his estimate to a loss of $9.25 from $7.80; for 2003, he estimated a loss of $4.50, bigger than his previous estimate of loss $3.90 per share. ©2002 Reuters Limited.