Incident Details
During a nighttime climb over water, the airplane was in straight and level flight, heading toward an intersection. The first officer was hand-flying the airplane with the autopilot disengaged. While climbing through 6,500 feet, the airplane unexpectedly rolled to the right, reaching a maximum bank angle of 65.5 degrees.
Crew Actions
The first officer responded by applying left aileron input, followed by left rudder input, successfully returning the airplane to level flight. The crew declared an emergency, dumped 20,000 pounds of fuel, and landed without further incident at the departure airport.
Environmental Conditions
The captain reported a thin deck of clouds at 6,500 feet and a dark night with no moon. The international relief pilot stated there was no discernible horizon, and the first officer reported no horizon, stars, or moon, only darkness. The captain also noted there were no traffic collision avoidance system alerts or engine indication and crew alerting system warnings during the event.
Investigation Findings
An examination of the airplane's systems revealed no mechanical or computer-related discrepancies. Analysis of digital flight data recorder data indicated that the rolls to the right were initiated by control wheel input.