critical systems failures. >> the plane begins to lose altitude. >> within a minute, they had lost several critical systems. they lost the radio contact. and very soon after that, we lost the transponder. >> inside the cockpit, a nightmare scenario is unfolding. fire has breached the ceiling, dripping molten aluminum on to the flight deck. they lose control of the plane and plunge into the ocean at 345 miles an hour. the impact is enormous. there are no survivors. the plane shatters and only small traces remain floating on the surface. the rest disappears into the atlantic. it is clearly now not a rescue mission but a recovery mission. puzzled by the tragedy, investigators are eager to retrieve the wreckage. >> we knew if we found the source of that in-flight fire