Flight Preparation
Prior to the flight, the captain received a company briefing. A convective SIGMET was in effect for the area, and turbulence was forecast. During the flight, the crew maneuvered the aircraft to avoid areas of turbulence.
Encounter with Turbulence
The aircraft was clear of clouds and in a thin haze layer when the crew felt a light bump. In response, the seat belt sign was turned on, the autopilot was disengaged, and the throttles were retarded. However, within seconds, the aircraft was subjected to negative G-loading.
Injuries to Flight Attendants
At the time of the upset, flight attendants were completing a beverage service and did not have time to strap in. As a result, one flight attendant sustained serious injuries, and three others received minor injuries.
Operational Details
The source does not specify the aircraft type, registration, engine count, date, operator, location, number of occupants, or time of day. No information is provided regarding weather characterization, ATC involvement, or damage to the aircraft.
Analysis
The source does not state any probable cause or contributing factors. No analysis, conclusions, or lessons are implied.