The biggest barrier to our blueprint for a fully secure airport? The price tag. It could cost tens of billions of dollars to upgrade existing terminals in all 429 commercial airports in the U.S., says James Gilliland, an airline bond market analyst at Fitch Ratings. That's an enormous amount of money, considering that the nation's airlines earned only $2.5 billion in 2000, the last year the industry was profitable. Consequently, the effort to build secure airports will likely be funded by higher ticket prices and new taxes. Still, despite the financial obstacles, many airport designers contend that within a decade, terminals protected by some combination of computers, lasers, smart cards, and biometrics will be as common as an airport without metal detectors was just 30 years ago.