Bus 429
Is BA approved to continue a revenue service after losing an engine on a 747 well before the PNR (like after take-off)? While the aircraft undoubtedly was safe on 3 engines, the margin for redundancy had been reduced. Was it really the right decision to continue?
Quite simply, in a word that even you may understand .... YES
... and BTW, wrt 4 engine ops, define PNR