MH370 search resumes amid optimism

AUSTRALIA

day that two new ‘‘ping’’ signals had been detected, bringing to four the number heard by a US Navy ‘‘Towed Pinger Locator‘‘(TPL), led officials to say they were confident that they were homing in on the remains of the plane.

‘‘We are still a long way to go, but things are more positive than they were some time ago,’’ Martin Dolan, chief commissioner of the Australian Transport Safety Board, which is involved in the search mission, said yesterday.

The black boxes record cockpit data and may provide answers about what happened to the plane, which was carrying 227 passengers and 12 crew when it vanished on March 8 and flew thousands of kilometres off its Kuala Lumpur-to-Beijing route.

But the batteries in the black boxes have already reached the end of their 30-day expected life, making efforts to swiftly locate them on the murky ocean floor all the more critical.

Efforts are now focused on two areas –a larger one for aircraft and ships about 2240km northwest of Perth and a smaller area about 600km closer to that city.

Based on data from the four signals detected, a modified Royal Australian Air Force P-3 Orion surveillance plane is deploying sonobuoys in the smaller search area to assist the US Navy listening device that detected the signals.

Each of the 84 sonobuoys is equipped with a listening device called a hydrophone, which is dangled about 300m below the surface and is capable of transmitting data to search aircraft via radio signals.

‘‘That does provide a lot of sensors in the vicinity of the Ocean Shield without having a ship there to produce the background noise,’’ said Australian Navy Commodore Peter Leavy, the operational head of the Australian search, referring to the ship carrying the US listening device.

But experts say that the process of teasing out the signals from the cacophony of background noise in the sea is a slow and exhausting process.

Operators must separate a ping lasting just 9.3 milliseconds – a tenth of the blink of a human eye – and repeated every 1.08 seconds from natural ocean sounds, as well as disturbances from search vessels.