Southwest Airlines Co. says a key revenue measure rose just 2 percent in July, in another sign that it's becoming harder for airlines to raise fares amid a weak economy.
The statistic measures revenue for each mile times available seats. It goes up when airlines raise prices, fill more seats, or do both.
July's increase -- reported Tuesday -- was the smallest all year for Dallas-baesd Southwest, which includes its AirTran Airways subsidiary in the figures.
The same thing happened at US Airways, which reported last week that the revenue statistic rose just 1 percent in July.
The latest attempt to raise fares, led by United Airlines, failed this week when Southwest declined to match the higher prices.