I'm in England right now, watching BBC morning news and they just said that they wanted to blow up 3 planes simultaneously over the middle of the Atlantic so it would be hard for forensics to detect anything.
That is what they say....
I think in fact they would wait for planes to reach land and then trigger an explosion that would drop over the city like rain of metal to increase the damage of the event.
I don't think they had any intent to be stealth over the ocean, that is illogical and makes no sense. But what do I know?
Oh dear GOD!