Incident Overview
A passenger aircraft experienced severe turbulence while in cruise flight. The seat belt signs were not illuminated at the time of the encounter. The aircraft's weather avoidance radar was active, and no weather was depicted on the radar screen. After being notified of passenger injuries, the captain assessed the situation, notified air traffic control, and requested a diversion to an alternate airport. The aircraft landed without further incident.
Flight Data Recorder Analysis
Review of the digital flight data recorder revealed that the aircraft was subjected to severe acceleration oscillations during the event. The vertical acceleration peaked at 1.81 g's upward, -1.38 g's downward, and 1.99 g's upward, with continued oscillations for a duration of 28 seconds.
Weather Review
An analysis of available weather data indicated no area of significant convection in the vicinity at the time of the turbulence event.