What happened
While cruising at FL330 in visual meteorological conditions, the aircraft encountered sudden turbulence. At the time of the event, the seatbelt sign was illuminated. Flight attendants were performing duties in both the forward and aft galleys to prepare for meal service when the disturbance occurred.
Data from the flight data recorder indicated that the turbulence consisted of two distinct pulses separated by an interval of 8 seconds. Each pulse reached a maximum vertical acceleration of +1.6 g's.
As a result of the turbulence, four flight attendants were injured; three sustained minor injuries, while one suffered a serious injury involving a fractured ankle. Additionally, two passengers located in the rear of the aircraft, who were not wearing their seatbelts, sustained minor injuries.