Incident
Approximately 33 minutes after takeoff, while cruising at Flight Level 330 (FL330), the captain of an airliner observed a weather cell ahead. The captain initially believed the aircraft would pass over the top of the cell, but as the airplane approached, the cell built up. The fasten seat belt sign was turned on, but none of the flight attendants were directed to be seated.
Sequence of Events
The airplane proceeded through the top of the weather cell. During this passage, the aircraft experienced five seconds of moderate-intensity turbulence. The turbulence caused two standing flight attendants and two passengers to fall.
Injuries
One of the flight attendants sustained a serious injury, while the two passengers received minor injuries. The source does not specify the nature or extent of the injuries beyond these classifications.
Aircraft Response
During the turbulence encounter, the airplane's altitude varied by a maximum of 400 feet. No other aircraft systems or structural damage were reported in the source.