Cruise-Altitude Turbulence Incident at 29,000 Feet (N12221)

Incident Overview and Flight Data Analysis The aircraft was operating in cruise flight at 29,000 feet in smooth air with the seat belt sign turned off. The crew reported two distinct jolts, after which the aircraft descended 600 feet. Flight data recorder readouts confirmed the aircraft was in cruise at 29,000 feet with no changes in heading, airspeed, or altitude for several minutes prior to the event. The altitude graph indicated a slight climb before the descent to 28,400 feet, followed by a slow recovery to 29,000 feet without oscillations. The total elapsed time from the initial altitude excursion to the recovery of cruise flight was approximately 75 seconds. ## Passenger Injuries and Diversion Due to possible injuries, the crew diverted the aircraft to Bermuda (BDA) and landed. Of the 155 passengers on board, one passenger sustained serious injuries, while 67 passengers received minor injuries. ## Weather and Forecast Information The flight was scheduled to climb from Flight Level 330 to Flight Level 370. Consequently, no information concerning forecast turbulence at Flight Level 290 was available to the flight crew. The High Level Significant Weather Prognosis chart for the relevant period indicated that no significant weather was shown in the area where the turbulence was encountered.