The slumping economy has forced some student pilots to put their dreams of flying on hold, threatened to accelerate the decline of the U.S. pilot population, and put a financial chokehold on flight schools. The number of U.S. pilots has fallen more than 25 percent from a 1980 peak of about 827,000 to about 590,000 at the end of 2008, according to the Federal Aviation Administration. While there are no more recent figures, the Aircraft Owners and Pilots Association is seeing some anecdotal evidence that the economy is taking a toll, said Chris Dancy, spokesman for the Frederick, Md.-based organization.