Bucking the first-quarter trend of deep losses, AirTran Airways ( AAI) Tuesday announced a first-quarter net profit that was double last year's total while topping Wall Street estimates.

The low-cost carrier, which competes with Delta Air Lines ( DAL) in Atlanta, said net first-quarter profit rose to $4.1 million, or 5 cents a share, the company's eighth consecutive quarter with a profit. This year's results are twice the $2 million, or 3 cents a share, it had a year ago and beats the 3-cent profit expected, on average, by analysts, according to Thomson First Call.

Revenue came in at $241.4 million, 16.1% higher than the $208 million it had in the year-ago quarter.

"Achieving our eighth consecutive profitable quarter in such a challenging economic climate should make every member of the AirTran Airways' team proud today," said Joe Leonard, chairman and CEO. "Having one of the youngest Boeing fleets in the world has paid huge dividends in a period of high energy prices."

The company's top-line growth continues to be fueled by massive expansion designed to hurt legacy carriers like Delta. In the first quarter the company boosted capacity, measured in available seat miles, by 21.1%, while traffic, measured in revenue passenger miles, rose 22.4%. With demand rising faster than supply, the carrier filled 68.5% of its seats, up from 67.8% from a year ago.

But in order to fill those seats, AirTran has been discounting seats -- a pervasive problem in the seasonally weak first quarter. The carrier said that its average fare was $78.43 in the first quarter, down 43 cents from last year's $78.86. With prices down, the carrier's yield, a measure of the money it takes in per passenger, fell 5.5% year over year.

That expansion will continue going forward. In mid-June, AirTran said that it would take delivery of its first Boeing 737s, adding the larger jet, a staple of low-cost carriers like Southwest Airlines ( LUV), to its existing fleet of 75 Boeing 717s.

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