Waves

Actually, not true. The FAA threatened fines and action against BA and backed down when presented with the Captain's authority in FAR 121 to continue the flight to LHR on three. If you don't think it is safe, how come we operate twins which start out with less redundancy of the 747 with three running and all systems operating. Heck, many 747 take-offs are at high assumed temps and power so reduced to be essentially three engine power.

GF