What about a 911 style hackjacking that went wrong after the terrorists got lost out to sea. lost their awareness and crashed into the sea.
Flying around for four hours, tells me they had a pretty good idea where they wanted to go..if it did crash at sea perhaps a few of the passengers did what Flight 93 did and tried to take back the plane and it crashed
“lost their awareness”
GOS based moving maps give them their exact location on a map.