On February 23, 2007, about 1222 coordinated universal time (UTC), a Boeing 777-200, N779AN, operated by American Airlines as flight 288, encountered moderate to severe turbulence during cruise flight. The international air carrier flight was being conducted under 14 CFR Part 121 on an instrument flight rules flight plan. One flight attendant was seriously injured. The remaining crew and 89 passengers were not injured. The flight departed Pudong International Airport (PVG), Shanghai, China, about 0951 UTC. The flight continued to the intended destination, O'Hare International Airport (ORD), Chicago, Illinois, landing about 2320 UTC. The captain reported that the airplane was established in cruise at flight level 340 near Japan when it "encountered a brief (2-3 second) but very intense moderate-to-severe turbulence event." He noted that continuous moderate turbulence continued for approximately 30 seconds, and periods of occasional-to-continuous moderate chop for about 10 minutes after the initial encounter. He added that there were no returns on the weather radar, and no pilot reports or adverse ride reports received from air traffic control. The fasten seat belt sign was on at the time of the encounter because the flight had encountered light chop after leveling off at cruise altitude. He reported that the ride had been smooth for approximately 10 minutes prior to the turbulence event. The autopilot remained engaged during the event. The injured flight attendant stated that she was working in the aft galley when the turbulence began. She reported that she hit her head on the ceiling and landed on the galley floor with her leg bent under her. She noted that a passenger came out of a lavatory and attempted to hold her down until the turbulence stopped. A flight attendant working in the aft cabin reported that the injured flight attendant was in the galley putting items away "when the aircraft suddenly drop[ped] and rose." She subsequently noticed the injured flight attendant on the floor being assisted by a passenger. The injured flight attendant was subsequently relocated to a first class seat and provided first aid. At the request of the NTSB, the operator downloaded the Flight Data Recorder (FDR) and provided the download file to the NTSB Vehicle Recorders Laboratory. Analysis of the data revealed that the flight encountered a vertical acceleration ranging from 0.245 G to 1.246 G. At the time of the encounter, the flight was located at 35 degrees 45 minutes north latitude, and 142 degrees 09 minutes east longitude. The airplane was operating at a pressure altitude of 34,000 feet. The data also indicated that the autopilot was engaged and no pitch inputs were made from the cockpit at the time of the encounter.