Ever-Ambitious AirTran Airways Grows at Expense of Competitors.

Sep. 14--Joe Leonard used to complain about hardball tactics by AirTran Airways' rivals. Back in 1999, when his carrier was struggling, the AirTran CEO griped that Atlanta foe Delta Air Lines should "quit investing in trying to kill us."

These days Leonard dares Delta and other big airlines to bring it on.

"We can put our business model where we want it, and there's not much our competitors can do about it," Leonard, AirTran's chairman and chief executive, told about 100 cheering employees at Hartsfield International Airport in July.

They were celebrating AirTran's order for up to 110 new Boeing 737 and 717 jets -- one of the biggest plane orders in years in the beleaguered airline industry.

If Leonard sounds a bit cocky, it's not without some justification. While Delta and other giants have racked up huge losses and struggled to restructure since 2001, the smaller and more nimble AirTran has cemented a remarkable comeback. Once stained by its heritage as ValuJet, and mired in red ink while the rest of the industry prospered in the late '90s, AirTran now flies high.

-- The Orlando-based airline, which has its flight hub in Atlanta, made money in five of the past eight quarters -- a period of historic losses for most large carriers.

-- AirTran's stock is up more than 350 percent this year. At $1.3 billion, its market capitalization -- stock price multiplied by outstanding shares -- rivals or exceeds that of Continental and Northwest airlines.

-- Employment is up 50 percent from two years ago, with 5,600 workers total and 4,000 in Atlanta.

-- Once limited to the Eastern Seaboard, AirTran launched its first flights this spring to the western United States, and the new 737s will double its fleet and enable it to build a nationwide route system.

One analyst even sees AirTran flying across…