FILE PHOTO -- American Airlines aircraft are parked at Ronald Reagan Washington National Airport in Washington, U.S., August 8, 2016. REUTERS/Joshua Roberts/File Photo

(Reuters) - American Airlines Group AAL.O on Tuesday raised its forecast for total revenue per available seat mile (TRASM), a key revenue metric, for the second quarter, citing improving yields and lower estimated fuel prices.

The No. 1 U.S. airline said it now expects TRASM to increase about 3.5-5.5 percent in the quarter, compared with its earlier forecast of a rise of 3-5 percent.

The company also said it now expects pre-tax margin, excluding certain items, to be between 12-14 percent for the quarter, up from its prior guidance of 11-13 percent.