Southwest Airlines reported softer September traffic on Friday as fewer passengers boarded its planes.
The Dallas-based discount carrier said traffic, measured by revenue passenger miles, fell 2.1 percent to 7.76 billion in the month from 7.93 billion a year earlier. Capacity, as measured by available seat miles, was down 1 percent.
Passenger revenue per available seat mile is estimated to have fallen by 2 to 3 percent in September from the year before. In the third quarter, unit revenue likely increased about 1 percent, Southwest added.
Barclays analyst David Fintzen had forecast revenue growth of 2 percent to 3 percent for Southwest in September.
"Southwest was lower, although everyone else has been lower to some degree this month," he said.
Earlier this week, Delta Air Lines said its unit revenue grew 0.5 percent in September, lower than it expected, partly because of lower walk-up traffic. Delta said bookings were solid and forecast a low-single-digit percentage improvement for October unit revenue.
Airlines typically see a seasonal drop in travel after the summer travel season.
Southwest said its third quarter traffic was down 0.6 percent as capacity shrank 0.7 percent.
Load factor edged down to 77.0 percent in September from 77.8 percent a year earlier.
Southwest is looking to maintain its dwindling low-cost advantage against bigger rivals that have cut costs in bankruptcy.
Maxim Group aerospace analyst Ray Neidl said other challenges before Southwest included successfully integrating its 2011 acquisition of AirTran and reworking its business model in a changed industry environment.