Been there, searched that ...
At the frequency and amplitude that the black box was pushing out, the depth of water, our Deep Diving Depth and the sensitivity of the sonar (not the main one, the one that looks downwards) we reckoned it would have taken us 2 1/2 years to cover the search area with any significant degree of confidence. On the other hand, we had an unplanned week's OSP in Fremantle over ANZAC day.