British Airways operated the aircraft in an unairworthy condition
Oh dear, I guess that means the end to three engine ferrying as well. Seems the answer is to have the relevent authority of every country the aircraft is to operate over put their stamp of approval on the ops manual and every other relevent bit of paper.
Flight With One Engine Inoperative
From Federal Aviation Regulation (FAR) 121.565 (excerpts):
(a) Except as provided in paragraph (b) of this section, whenever an engine of an airplane fails or whenever the rotation of an engine is stopped to prevent possible damage, the pilot in command shall land the airplane at the nearest suitable airport, in point of time, at which a safe landing can be made.
(b) If not more than one engine of an airplane that has three or more engines fails or its rotation is stopped, the pilot in command may proceed to an airport that he selects if, after considering the following, he decides that proceeding to that airport is as safe as landing at the nearest suitable airport
(1) The nature of the malfunction and the possible mechanical difficulties that may occur if flight is continued.
(2) The altitude, weight, and usable fuel at the time of engine stoppage.
(3) The weather conditions en route and at possible landing points.
(4) The air traffic congestion.
(5) The kind of terrain.
(6) His familiarity with the airport to be used.
(c) The pilot in command shall report each stoppage of engine rotation in flight to the appropriate ground radio station as soon as practicable and shall keep that station fully informed of the progress of the flight.
As SLF and not knowing 747 capabilities, on the basis of the above FAR seems they did OK to me. ie thumbs up