What happened
A Boeing 747-238B operated by Continental Airlines departed Tokyo on a scheduled passenger service bound for Honolulu, Hawaii. Prior to the event, the crew noted that turbulence had been included in the flight forecast.
Approximately 59 minutes into the flight, while cruising at FL330 under dark night conditions, the captain noticed a sudden fluctuation in the outside air temperature. Shortly after this observation, the aircraft entered an area of wave activity. The captain activated the seat belt signs, and within 5 to 8 seconds, the aircraft encountered severe clear air turbulence (CAT). This period of intense turbulence lasted for approximately 10 minutes. Following the encounter, the flight continued to its destination in Honolulu with no injuries reported.
The investigation
An analysis of meteorological data revealed that two jet streams were traversing the region at the time of the event. One jet stream was located at 34,000 feet with winds of 160 knots, while a second jet stream was situated to the south at 39,000 feet with winds of 180 knots. These two streams were generally diverging in the vicinity of the turbulence.
Satellite imagery captured during the encounter showed a band of high-level clouds in the immediate area. These clouds were arranged in a northwest-to-southeast orientation, perpendicular to the wind flow pattern. This specific formation is consistent with transverse wave cloud patterns often associated with clear air turbulence encounters. Investigators found that neither the cockpit voice recorder nor the flight data recorder provided useful information regarding the event.