Event Overview
On February 10, 2011, at 0830 Hawaiian standard time, a Boeing 767-300 (Japan registry JA603J) operated by Japan Airlines International Co., Ltd. as Flight JAL074 experienced a turbulence event while descending through 34,668 feet mean sea level, approximately 4 miles south of Ni'ihau, Hawaii. The flight was a commercial passenger service under Title 14 Code of Federal Regulations Part 129, originating from Narita, Japan. Visual meteorological conditions prevailed, and an instrument flight plan was filed. The airplane was not damaged.
Flight Crew Actions
The flight crew reported that after starting descent from 38,000 feet, the tailwind increased from about 60 knots to 65-70 knots, with cumulonimbus clouds observed ahead. As the airplane descended through about 34,668 feet, the tailwind suddenly dropped, and airspeed quickly accelerated. The captain deployed the speed brake, disengaged the autopilot, and the airplane gradually slowed. As the captain slowly retracted the speed brake, the co-pilot noted the airplane was starting to climb. The captain then slowly pitched the nose down.
Injuries and Passenger Account
During the event, one passenger suffered a broken femur. The passenger was outside the aft lavatory when she felt her body sink and fell to the floor, colliding with cabin objects throughout the turbulence. One cabin attendant in the aft galley felt her body float halfway to the ceiling and fell onto her knees. She floated a second time, struck her head on the ceiling, then fell onto her right side, hitting her face and elbow on the floor but was not seriously injured. In total, one passenger was seriously injured; two cabin attendants and four passengers received minor injuries. The flight crew was not injured.
Digital Flight Data Recorder Analysis
The Japan Transport Safety Board downloaded data from the airplane's digital flight data recorder and provided it to the National Transportation Safety Board’s Vehicle Recorder Laboratory. According to the DFDR data, the event occurred at 18:30.05 UTC (0830 HST) at 34,964 feet msl. Vertical acceleration dropped from approximately 1 g to 0.76 g in less than 1 second. About 6 seconds later, at 08:30:11, vertical acceleration peaked at 2.33 g while pressure altitude leveled around 34,634 feet msl. Approximately 2 seconds later, at 08:30:13, vertical acceleration decreased to 0.05 g, and about 22 seconds later, at 08:30:35, it settled to approximately 0.9 g.
Weather Conditions
A weather synopsis by an NTSB meteorologist revealed convective activity approximately 20-40 miles west of the event location. Satellite imagery showed several high-level cirrus cloud bands moving eastward toward the area. The Lihue sounding indicated a maximum wind level from 280° at 71 knots at 38,000 feet. At 34,000 feet, wind was estimated from 294° at 49 knots with a temperature of -46°C. The event occurred in clear air, downstream of cumulonimbus clouds, within a strong temperature inversion and wind shear. No turbulence was predicted by weather forecasters for the location.