Search for MH370 goes below sea

Updated April 17, 2014

Efforts to recover missing Malaysian Airlines flight MH370 have gone below the sea surface with the deployment of a towed pinger locator system. 

Australian Defence Vessel Ocean Shield has been fitted with a US Navy TPL-25 towed pinger locator, plus a Bluefin-21 Autonomous Underwater Vehicle, to pinpoint signals from the transponder, or pinger, attached to the missing aircraft’s black box recorder.

The Australian Maritime Safety Authority has determined a search area of about 217,000 square kilometres, 1,700 kilometres north west of Perth and today’s search – with up to 10 military aircraft, four civil jets and nine ships - will focus on three areas in the same vicinity.

The TPL-25 system includes a towed, underwater hydrophone, a tow cable and a shipboard processor suite. In use, it can detect a signal from a distance of approximately one mile with a maximum depth of 20,000 feet. 

Once deployed, the hydrophone will be kept approximately 1,000 feet above the sea floor while Ocean Shield executes a search pattern at speeds between 3-5 knots.