Fourteen Continental passengers were sent to the hospital Monday after encountering clear-air turbulence over the Caribbean, and the incident has focused attention on a "persistent concern" for commercial aviation. The NTSB says about 10 people each year sustain serious injuries during turbulence, and the FAA says the cost to airlines is about $28.5 million per year. Though technology currently cannot detect clear-air turbulence, scientists are working on several predictive tools. Still, some experts say the best way to avoid turbulence is to improve communication among airliners along the same route and to allow pilots more latitude in adjusting their course.