Incident Overview
At approximately 1458 Pacific Standard Time, an aircraft experienced a sudden encounter with moderate to severe clear air turbulence during its climb through 35,500 feet. The turbulence lasted for 8 to 10 seconds, according to the investigation.
Injuries and Seat Belt Compliance
The event resulted in minor injuries to seven passengers and seven flight attendants. The seat belt sign had been activated before takeoff and remained illuminated throughout the flight. Among the injured passengers, four reported that their seat belts were unfastened at the time of the turbulence, two stated their belts were loose, and one had disregarded the illuminated sign and was in the lavatory. The injured flight attendants were preparing for cabin service and were not restrained.
Weather and Turbulence Forecasting
A review of the airline's computer-generated flight plan data indicated that the maximum predicted turbulence index was light. However, a Convective SIGMET for clear air turbulence was valid for the period, reporting moderate turbulence at flight levels 360 to 370 over southern California in the Hector-Thermal area. The aircraft encountered turbulence at a slightly lower altitude of 35,500 feet.