Boeing B-747 Turbulence Incident During San Francisco to Hong Kong Flight (N119UA)

Flight Overview and Weather Conditions A Boeing B-747 departed San Francisco for Hong Kong. Before departure, no significant meteorological notices or forecasts for turbulence were issued for the Alaska Peninsula, the area over which the flight was scheduled to pass. The aircraft maintained radio and data link communications with Oakland ARTCC, then ARINC, and finally Anchorage ARTCC. ## Turbulence Encounter and Injuries Anchorage ARTCC recorded a PIREP at 1432 for moderate turbulence and an urgent PIREP at 1600 for severe turbulence in the incident area. As the flight entered the Alaska ARTCC area, a delay in establishing communications with the aircraft also delayed the transmission of the urgent PIREP concerning turbulence in the flight's area. The crew observed rolling clouds ahead and instructed the cabin flight attendants to be seated. At 1620, while cruising at 31,000 feet, the aircraft encountered moderate to severe turbulence. Approximately five seconds after the seating notification, three cabin attendants were thrown to the floor. ## Diversion and Damage The captain diverted the flight to Anchorage. Upon arrival, a belly-mounted fuselage panel enclosing an air conditioning unit was found missing. ## Communication and Advisory Systems Aircraft conducting oceanic flights are equipped with ACARS, allowing flight crews to receive ATC clearances and weather data via controller/pilot data link communications (CPDLC). Anchorage ARTCC was not utilizing CPDLC because its software was not user-friendly, required substantial controller input for free-text messaging, and was not as fast as voice communications. Hazardous inflight weather advisories are reviewed by each center weather coordinator in conjunction with the National Weather Service for dissemination to pilots. The FAA does not have a direct mechanism to alert air crews of significant weather in one sector occurring in another sector, nor does it have a mechanism to coordinate CPDLC data from an ARTCC sector to ARINC. A SIGMET for occasional turbulence was issued by the National Weather Service at 1619.