Sonobuoy detection
Refer to my post #9674
It was Commodore Levy (Sp) who mentioned at the Wednesday briefing that the RAAF had modified the aircraft systems to allow the deployment of the AP-3C Orions to undertake a passive search in the area. As an ex fish head the use of a sonobuoy pattern in the ocean to detect and localise a target is one of the first and basic detection methods used in Anti Submarine Warfare for over 50 years.
If the ping stays long enough a series of bearings can be obtained, or they were able to in the older P2 and P3 aircraft equipment that would greatly reduce the area of probability for the final underwater search phase.
What a wonderful effort that is going into this search.