IF the plane went down on the water, and
IF we knew EXACTLY where, and
IF we knew exactly the planes heading as it sat in the water,
WE STILL WOULDN'T KNOW WHERE THE HELL IT WAS.
As the plane begins to sink, the wings, (airfoils) become HYDROFOILS and would begin to 'fly' in the water as it sank. And with depths of 4-6 miles, that could be a lot of forward movement.