Of these and other changes intended to increase revenue at Southwest, Mr. Kelly said, “It’s going to take us the entire decade.” The hedges, he said, “bought us time to retool our company.”

Indeed, in recent years other carriers could identify investments they needed to make — redoing airplane interiors to compete against foreign airlines, upgrading computer systems to improve employee productivity and airline reliability — but they often lacked the money for the projects. All but American Airlines among the major hub-and-spoke carriers have spent time in bankruptcy, and American only narrowly avoided it.

Other airlines certainly could have hedged in the late 1990s when they were solidly profitable. But they were a little giddy over that decade’s boom, entering into expensive labor agreements and, in some cases, buying new planes.

Since Sept. 11, 2001, some airlines have been too broke to hedge; many agreements between parties in the energy derivatives market require players either to have a strong credit rating or to post collateral. Also, some forms of hedging are expensive.

Southwest’s hedges used during the first nine months of 2007, which included options that allowed — but did not require — it to buy energy products at certain prices, cost $42 million. A small sum in retrospect, but not so easily spent when higher oil prices were only a possibility.

Early this year, more airlines were in decent financial shape and, with oil at about $52 a barrel, it would have been a smart time to do some hedging. “Everyone was tired of having Southwest’s advantage rubbed in their noses,” said Frank Boroch, an analyst at Bear Stearns.

Still, airlines did very little. “Maybe they were distracted,” Mr. Boroch said, noting that US Airways was trying to buy Delta during this period. “It’s a copycat industry. If everybody is in the same boat, that’s going to give you comfort, or an excuse.”