DumboLives · Today 20:47
^if they could not find the plane mh370 when it went down, they stand next to no chance of finding the sub.
The plane went down in an unknown area, hundreds of thousands of kilometres across. The tools they used were not really well suited for searching for small debris items, as they had to fly the equipment higher than optimal.
(I'm in the marine survey industry and know a few people who were on the job, on the Fugro Discovery - I've been on it in the North Sea).
This is a much smaller area, a few square kilometres and they are likely to have gone to one of the larger pieces of the wreck.
If they can't be found with a visual survey, the terrain is far better suited (much flatter and less rugged than much of the Pacific search area) to using side scan sonar to locate it.
It cannot navigate by itself, it needs the mothership.
It most certainly can, it will have at least two inertial navigation systems, gyrocompasses, pressure and depth sensors. If it couldn't navigate, they wouldn't be able to get to the location of the wreck.