B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 200; Flight Crew Total 8500; Flight Crew Type 1200
Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew FLC Overrode Automation; Flight Crew Regained Aircraft Control; General Maintenance Action
Weather
Aircraft at cruise level 350 over southern tip of Greenland. Encountered continuous moderate and occasional severe turbulence. Vertical speed changes of +/- 800 feet; airspeed loss and gain in excess of 30 knots with near over speed from an established cruise of .78 mach; bank deviations in excess of 20 degrees; rapid and erratic autothrottle movement which had to be manually controlled and dampened. Left yaw damper disengaged during event and was later successfully reset. No injuries reported. Flight attendants in rear of aircraft reported lying on the floor and holding on to the base of seats in the rear of the aircraft to keep from being tossed about even though they were given several minutes of warning ahead of time to take their seats with the expectation of possible moderate turbulence ahead as had been reported by an aircraft 20 miles ahead on the track. The event lasted about 20 minutes total. Three other aircraft on the same track at different altitudes reported severe turbulence encounters with one declaring a PAN PAN PAN emergency and ultimately leaving the route. The event was reported to Maintenance and the aircraft was to be removed from service for inspection. The Captain was in the crew rest facility at the time of the event. I; the Relief Pilot; was acting as pilot flying and the other First Officer was acting as pilot not flying.
A B-767ER flight suffered an extended encounter with moderate to severe turbulence over the North Atlantic.  Upon arrival the aircraft was removed from service for an inspection.