NTSB Identification: SEA99IA032.
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Incident occurred Wednesday, January 20, 1999 in PACIFIC OCEAN
Probable Cause Approval Date: 06/22/2000
Aircraft: Boeing 747-238B, registration: N14024
Injuries: 14 Minor,340 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The Continental Airlines Boeing 747-238B departed Tokyo en route to Honolulu on a regularly scheduled passenger flight. The crew reported that turbulence had been forecasted. Approximately 59 minutes after departure, while cruising at FL330 in dark night conditions, the captain observed a sudden fluctuation in outside air temperature and the aircraft entered an area of wave activity. The Captain illuminated the seat belt signs and within 5-8 seconds the aircraft encountered severe clear air turbulence (CAT) which lasted for approximately 10 minutes. The aircraft continued on to its destination of Honolulu, Hawaii. Review of meteorological information indicated two jet streams traversing the area, one at 34,000 feet at 160 knots, and the other to the south at 39,000 feet at 180 knots. The jet streams generally diverged in the area of the event. A satellite image taken at the time of the event indicated a band of high level clouds in the immediate area. The clouds were aligned in a 'band' formation oriented northwest to southeast, and perpendicular to the wind flow pattern. This pattern was similar to previous CAT encounters with transverse wave cloud patterns. No useful information was available from either the cockpit voice or flight data recorders.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

An encounter with Clear Air Turbulence at Flight Level 330.

Full narrative available

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