19971228039379A

Narrative: about one hour-forty minutes after takeoff, at 1840Z, in the vicinity of N82-30 latitude, E158-60 longitude, the captain observed slow variations in vertical speed and altitude. He turned on the seat belt sign and the second officer made the customary announcement. The captain checked the weather radar which showed nothing directly ahead. Outside, there were no clouds in sight. The sky appeared clear and numerous stars were visible. He saw an airplane above them and slightly ahead. The captain called northwest 90, who was on the same track and about 30 miles ahead of the flight, and requested his ride conditions. He reported "an occasional ripple" but basically a smooth ride. The captain indicated his conditions could of been described the same way. Suddenly the flight was jolted by severe turbulence. The captain made a pa announcement for flight attendants to be seated. The severity of the turbulence made pilot actions very difficult for several seconds. Red warning lights appeared on the number one and three ins units, and the number four hydraulic system low pressure light came on. Ins malfunction codes were cleared, and the second officer returned the number 4 adp & edp switches to the on position. Control of the airplane was maintained with normal inputs and there was no evidence of external damage. The captain made a passenger announcement explaining that they were following the smoothest possible path. The captain then called the chief purser and asked for a cabin report. The purser reported everyone he could see appeared to be ok, but he could not see the rear. The captain requested a report on the entire cabin. In the meantime, all three pilots discussed options as well as the aircraft integrity and systems. The captain broadcasted their experience to all aircraft on 128.95 and received an offer of assistance from united flight 824. Northwest 22 called and advised that he had vacated FL330, and immediately requested higher from Tokyo ATC. Clearance was received promptly, and the first officer climbed to the higher altitude. Shortly thereafter, the purser reported numerous injuries and an unconscious passenger. The captain directed the purser to page for a doctor. The chief purser came to the cockpit to report he had found a doctor, and the medical kit was required. The captain sent the second officer to get more information on the cabin condition. Following the second officer's return, the captain visited the cabin and conversed with the injured flight attendants. He asked the purser to determine the doctor's opinion on further medical assistance. Minutes later, the doctor recommended the flight land as soon as possible. The flight immediately initiated a return to Tokyo's Narita airport and the pilots obtained an ATC clearance. The flight landed at 0219 Tokyo time. One passenger reportedly received fatal injuries as a result of the turbulence upset. The incident is currently under investigation by the national transportation safety board. Jeff plantz, united airlines, flight safety. (.19) on December 28, 1997, at 2310 japanese standard time (1410 UTC), a united airlines Boeing 747-122, N4723U, experienced an episode of severe turbulence (two closely spaced turbulence encounters) about 950 miles southeast of new Tokyo international airport, Narita, japan (nrt) on pacific ocean navigation track 12. Navigation tracks are over ocean routes that are assigned to flights to separate them from other overwater aircraft in a non-radar environment. Aircraft report to oceanic air traffic control facilities at fixed reporting points, thus notifying these facilities of their flight progress. The airplane was operating under 14 code of federal regulations (CFR) part 121 in visual meteorological conditions at the time of the accident and was bound for honolulu, Hawaii (hnl). 374 passengers including 5 infants and 19 crewmembers were on board. Twelve passengers and one flight attendant received serious injuries and one passenger was killed. An unknown number of minor injuries were sustained by flight attendants and passengers. Following the turbulence encounter, the airplane returned to new Tokyo airport for an uneventful landing.