Air Canada Flight 965, a Lockheed L-1011, C-FTNJ, with 145 passengers and 15 crewmembers on board, encountered severe turbulence about 105 miles off the coast of Charleston, South Carolina, while en route to Toronto, Canada, from Port of Spain, Trinidad. At 19:16, the flight had been cleared to climb and maintain flight level (FL) 370 from FL 350. About 2 minutes later, the ground controller asked the flight to start a turn to the north because of other traffic. The captain stated that he may have to detour around some thunderstorms and also replied that he was in the turn. About 8 minutes later, the flight encountered severe turbulence which lasted several seconds. One flight attendant and three passengers were seriously injured during the encounter, and two physicians aboard the flight provided immediate medical attention. The flight continued to its destination and landed without further incident about 1 1/2 hours after the accident. The National Transportation Safety Board determines that the probable cause of the accident was an encounter with severe clear air turbulence produced by the intrusion of thunderstorm cells into strong winds aloft.