On October 17, 1995, at 0944 UTC (1944 local meridian time), six passengers were injured onboard United Airlines Flight 806, during a severe turbulence encounter over the Pacific Ocean. The aircraft, a Boeing 747-422, N191UA, was operated by United Airlines, Inc., as a regularly scheduled non-stop international passenger flight from Hong Kong to San Francisco. The accident occurred in international waters near latitude 40 degrees north, longitude 152 degrees east, while the aircraft was in cruise at flight level FL330. The aircraft was not damaged. One passenger sustained serious injuries and five additional passengers incurred minor injuries. The remainder of the 309 passengers, 18 cabin attendants, and flight deck crew of four were not injured. The flight originated from Hong Kong at 0516 UTC. Copies of the original dispatch package given to the flight crew prior to departure was obtained and examined. Weather data and forecasts given to the crew were included as part of the package. Examination of the forecasts and pilot reports disclosed that an area of light to moderate turbulence was forecast along the aircraft's planned track from 151 to 162 degrees east longitude. Pilot reports available at the time of departure consistently reported smooth conditions in the area of the forecast turbulence. According to flight and cabin crew statements, the aircraft was in level cruise flight at FL330 in clear air above a cirrus cloud deck. The crew saw no convective activity ahead either visually or on radar. In the process of preparing for a position report to air traffic control, the flight crew overheard a Delta Airlines flight, which was ahead of them on their assigned track at FL350, reporting an encounter with moderate to severe turbulence. The captain decided to secure the cabin as a precaution. The purser was notified of the decision and the captain was in the process of reaching for the seat belt sign when the turbulence was encountered. The crew described the encounter as "one sudden heavy jolt," accompanied by airspeed and altitude excursions of plus and minus 20 knots and 200 feet from the respective cruise target values. Moderate turbulence then continued for about 20 minutes thereafter. All of the injured passengers were located aft of row 50, with the majority aft of row 58. None of the injured were secured by seat belts. The 62-year-old female passenger who was seriously injured was in the 5R lavatory at the rear of the aircraft at the time of the encounter. Her injuries consisted of compression fractures of several lumbar vertebrae. A table is appended to this report which denotes the exact location and activities of the injured passengers at the time of the encounter.