SAN FRANCISCO — The federal government has taken billions of dollars from the taxes and fees paid by airline passengers every time they fly and awarded it to small airports used mainly by private pilots and globe-trotting corporate executives.

Some of these "general aviation" facilities used the federal dollars — more than $7 billion over the past decade — for enhancements such as longer runways and passenger terminals aimed at luring traffic, an Associated Press review has found. And the money comes with little oversight and at the expense of an increasingly beleaguered air transportation system.

"They're making out like bandits," said Bob Poole, director of transportation studies at Southern California's Reason Foundation and author of several studies on air transportation costs. "It's not only that airline passengers are paying more than their fair share, but they're being overtaxed to give private jets a free ride."

Passengers pay as many as six separate taxes and fees on a single airline ticket, adding up to more than $104 billion since 1997, the AP found. Yet these assessments often are overlooked by the millions who click the "buy" button to purchase tickets online, even though they can exceed 25 percent of the total airfare.

Meanwhile, travelers deal with more hassles than ever. In 2006, more passengers were bumped, their flights delayed or their bags lost than in 2005, according to the annual Airline Quality Rating report released earlier this month.

"What are people getting for their money?" said Kenneth Button, a professor of transportation at George Mason University's School of Public Policy and an expert on air transit taxation. "Delays are increasing. How can consumers make a sensible assessment on how the money is being spent? You need an abacus to figure out all the costs."

Congress will decide later this year whether to curtail the huge public subsidy for small airports, while pilots' associations, airport managers and other interested groups are fighting to keep it.

Ed Bolen, president of the National Business Aviation Association, which represents 8,000 operators of private jets and other aircraft, said all Americans benefit from the proliferation of small airports throughout the country. They aid emergency preparedness and critical services such as medical evacuations and mail delivery, he noted.

Without help from the federal government in the form of passenger taxes, many would be unable to survive, Bolen said.

"Not all aircraft are the same nor do they impose the same costs on the system," he said. "If we were grounded tomorrow, the system would cost the same."