Southwest Airlines Co. said a key measure of passenger revenue rose as much as 8 percent last month as it benefited from fare increases even as its planes carried fewer people.
Airlines measure how much money they collect for each seat flown one mile.
Dallas-based Southwest on Monday estimated that figure rose an estimated 7 percent to 8 percent compared to April 2011. Southwest combined data from both years with AirTran, which it bought on May 2, 2011.
Traffic on the combined airline fell 2.1 percent compared to April 2011. Southwest cut flying capacity by 1.9 percent. Because traffic and capacity fell by similar amounts, Southwest's planes were about as full as a year ago -- 79.8 percent, down by 0.1 percentage point from a year ago.