The detection of special signals by underwater listening devices has limited the search for wreckage location of missing Malaysia Airlines Flight MH370 to a 600km corridor of the Indian Ocean.
The 37.5 kHz “pings” heard by Australian and Chinese ships on April 5 have allowed the search teams to narrow their efforts.
In the image above, the shape of the sea bed, on a line drawn between the two points at which the signals were detected, is shown. The depth ranges between 3,000 m and more than 6,000 m within the “corridor”.
Detailed models of the ocean in the search area are currently being assembled by the Commonwealth Scientific Industrial Research Organisation (CSIRO), with the help of satellites.
The organisation's oceanographer, David Griffin, explained that if the location of the detected signals had correctly identified the crash site, multi-directional ocean currents would explain why it had been difficult to locate any wreckage.
Another oceanographer, Simon Boxall, told the BBC that the signals could help narrow the hunt for debris. For instance, the search area may go down from 136,000 sq kilometres to about 16 sq kilometres if the data is precise.
Currently the “pings” are lost. When the signal is picked up again, search crews could deploy the autonomous mini-submarine Bluefin-21, which can create a detailed map of the sea bed using sonar, and possibly also spot the wreckage.
Unfortunately, this model can only operate to depths of 4,500 metres. In case the debris is in deeper water, other more specialised equipment will have to be brought in.
The Remus and Remora unmanned mini-subs, which were used in the search for missing Air France flight 447 back in 2011 at depths of 6,000 m, may suit for this mission.