Leon said "Maybe this is the crew we should have sent to the west coast of Australia? So far the MPAs have seen and heard nothing - only the ships have managed to locate a pinging sub-surface target!
"
The "pinger" transmits at 37.5 KHz
+ 1 KHz which is just slightly outside the frequency range of even the most modern airborne acoustic systems and sonobuoys. (And most ship systems as well - hence the specialist equipment brought in on only a couple of platforms)