B767 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Regained Aircraft Control
Environment - Non Weather Related; Procedure
At [approximately] 18W on NAT C at FL310 SLOP R1 we encountered moderate wake turbulence. We saw northerly winds and decided to offset to R2.At that point it was smooth. Then wind shifted to SW direction which prompted us to return to R1 offset. We could see contrail of an aircraft at FL340 so we turned toward R1 and away from his contrail. Suddenly we hit severe wake turbulence and were in a 30 degree bank and climbing. The First Officer; pilot flying; disengaged the autopilot to control the aircraft altitude and attitude. Control was regained but not before we climbed approximately 300 feet. We learned later that a B747 was ahead and 1000 FT above us. The aircraft at FL340 was a B767 and not the source of our encounter.
B767 Captain reported wake vortex encounter over the North Atlantic from a B747 ahead and 1000 feet above them that resulted in a 30 degree bank and an altitude deviation.