Southwest Airlines and AirTran Airways report higher traffic, increase in key revenue number

Southwest Airlines Co. said Thursday that it carried more passengers and a key revenue statistic rose by about 5 percent in September, compared with a year earlier.

Passengers on Southwest and its AirTran Airways subsidiary flew 8.27 billion miles last month, a 5.1 percent increase over September 2013.

The Dallas company kept the supply of seats nearly unchanged — just a 0.7 percent increase — so the average flight was 80.5 percent full, up from 77.1 percent a year earlier.

That helped Southwest boost passenger revenue for every seat flown one mile grew by an estimated 5 percent. That is a closely watched statistic in the airline industry, and it increases when an airline fills more seats, charges higher average fares, or both.

Southwest shares gained 12 cents to $32.35 in morning trading. They started the session up 71 percent in 2014.