QuakerOats;1611350 wrote:Did not know of the "certainty" they had ....................and of course the depths could be massive, potentially out of reach ??
Where the sonar mapping searched was near the limits of its depth, but mostly within those limits. Hilly/mountainous bottom can also be a problem, but it was mostly fairly flat.
They were highly confident the "pings" they had picked-up could only have been from a blackbox - it pings at a measurable frequency that is intentionally distinct from marine life and man-made objects (not sure what that could be other than a sub). So they had multiple "confirmations", which should have ruled out human error (the most likely source of mistake). They had multiple independent detections (from presumably different crews) around the same area of the source, i.e. "verification".
I'm only speculating, but I think the depth might have prevented any tell-tale bottom disturbances resulting from sinking wreckage. Also, depending on the angle of impact it's possible the plane disintegrated into thousands of tiny pieces that such sonar wouldn't detect.
Just remember, it took over 2 years to find the bulk of the wreckage and black box with the Air France flight and they had known approximately where it went down. Not sure if it's the same tech, but that small debris field (@ 30 acres) was located with side-scan sonar that failed here. A depth of 13k feet, which is comparable to the depths of most of this search area.