The Aviation and Transportation Security Act mandates that by December 2002 100 percent of checked baggage be screened. Can this schedule be met? RAND assessed the feasibility of using explosive detection system machines or whether less-expensive explosive trace detection machines could shoulder part of the load. After studying operations at Dulles and Dallas-Fort Worth Airports, the authors concluded that a bottom-up approach an airport-by-airport basis was better than the top-down approach mandated by the FAA. They identified six problem areas and propose improvements that, while not meeting the deadline, will increase security.