there are other tools out there, rovs, auvs, and, of course, submersibles that have their depth limits that can be used in this particular circumstance in the right order and in the right fashion and only if we have tangible evidence of where to search. >> reporter: now we're learning resources are pulling out of search. the royal navy today says the hms tireless, the only submarine in the search, is done. saying there is no longer any prospect of detecting black box pings. and now one of the surface ships, the hms echo returning to port to refuel, leaving it out of the loop for now. and as for that underwater search, we expect crews to shift to the north from where they're searching right now very soon. possibly this weekend. wolf? >> all right. pamela, stand by. i want to two to the base of the operations for the search. cnn's miguel marquez joining us once again. liveaustralia. what are you learning there, miguel? >> reporter: look, we know