Capt Fathom
Of course you are assuming that he was flying the Great Circle route. While I don’t know the exact circumstances of this flight, I would has it a guess that he was well on the southern side of this taking advantage of the Jet Streams that prevail this time of the year. All in all the failure occurred at 100” after take off LAX. Plenty of time to modify the flight plan and divert to JFK. BA has lots of flights to JFK and it wouldn’t be too hard to protect all the PAX on to LHR.