Incident Details
Six passengers sustained injuries during a turbulence encounter while the aircraft was in cruise at flight level FL330 over the Pacific Ocean. The event occurred near latitude 40 degrees north, longitude 152 degrees east, in international waters. At the time, the aircraft was flying in clear air above a cirrus cloud deck. No convective activity was visible to the crew either visually or on radar.
Weather and Forecasts
The dispatch/weather package provided to the flight crew prior to departure included forecasts indicating an area of light to moderate turbulence along the planned track from 151 to 162 degrees east longitude. However, pilot reports available at the time of departure consistently described smooth conditions in that area.
Crew Actions
While preparing for a position report to air traffic control, the flight crew overheard another airline aircraft ahead reporting an encounter with moderate to severe turbulence. In response, the captain decided to secure the cabin as a precaution. The purser was notified of this decision, and the captain was reaching for the seat belt sign when the turbulence occurred.
Passenger Injuries
All six injured passengers were located aft of row 50, with the majority aft of row 58. None of the injured passengers were secured by seat belts at the time of the encounter.