Well I've flown 747s around on 3 engines quite happily. I do not believe 'land as soon as possible' is sensible or desirable. But you know what a can of worms this is opening! I would rather be in a 747 on 3 engines than any twins or trijets with all engines working! Until you know a 747, you cannot criticise it. But there are many factors to weigh up: weather, alternates, fuel reserves, spare engines, maintenance capabilities. It's not just a yes/no decision. Anyone who is interested can dig up the old BA thread!