At 35,000 feet you have about 30 – 60 seconds of useful consciousness if I am not mistaken. They can’t find the wreckage and think that it is in the sea. I’m not sure if Dakar has radar these days, if so they would have tracked it. The initial report mentioned something about searching 110km off the coast. There is also the question of why did the Hawker not show up on the Boeing’s TCAS, or did it?