After a decade of multibillion-dollar losses, U.S. airlines appear to be on course to prosper for years to come for a simple reason: They are flying less.

By grounding planes and eliminating flights, airlines have cut costs and pushed fares higher. As the global economy rebounds, travel demand is rising and planes are as full as they've been in years.

Profit margins at big airlines are the highest in at least a decade, according to the government. The eight largest U.S. airlines are forecast to earn more than $5 billion this year and $5.6 billion in 2012.

U.S. airlines are in the midst of reporting fourth-quarter results that should cap the industry's first moneymaking year since 2007.

"The industry is in the best position — certainly in a decade — to post profitability," says Southwest Airlines CEO Gary Kelly. "The industry is much better prepared today than it was a decade ago."