Traffic and average prices weakened in September but analysts believe Southwest Airlines still made money in the third quarter.
Dallas-based Southwest, which carries the most passengers within the U.S. of any airline, is scheduled to report financial results on Thursday. The report will cover the last two months of summer and the beginning of autumn, when business travelers replace vacationers in the sky.
Traffic, measured in how many miles passengers fly, was flat in July and August, but fell 2.1 percent in September, compared with the same months last year.
Fort Worth-based American Airlines, United Airlines and Delta Air Lines also saw a drop in domestic traffic last month. American parent AMR Corp. last November filed for bankruptcy protection.