thanks, barbara starr. let's look at the other side. the possibility that maybe there wasn't a villain, be it a potential hijacker but it was one horrific accident. joe johns, you've been looking into that for us. what is it about the flight path and behavior that tells investigators that it could be accidental as opposed to intentional. >> jim, this goes into the category of things that can't be ruled out as long as a black box is not recovered. a sudden change in direction suggests that something went wrong on the plane very rapidly. if that's true, the plane dropped altitude rapidly, that could have been because of a sudden decompression problem which could be explained by any breach, a big fire, explosion, even an open door. with this scenario, there could have only been seconds to react before passing out. the pilots would have been trying to get the plane to an altitude where the people on