A more serious event occurred in 1985 which according to Boeing validates its design philosophy. A China Airlines 747SP en route from Taipei to Los Angeles cruising at FL410 had a number 4 engine failure accompanied by the autopilot disconnecting. The surprised crew failed to correct with left rudder and the plane rolled right, entering a steep dive. After descending over 30,000 feet in a steep rolling dive, the captain was able to recover control at 9500 feet.
