MH370 search: Australian ship Ocean Shield detects signals

An Australian navy ship has detected new signals 'consistent' with aircraft black boxes, a senior official said Monday as the hunt for missing Malaysian flight MH370 went on.

"The towed pinger locator deployed from the Australian defence vessel Ocean Shield has detected signals consistent with those emitted from aircraft black boxes," Angus Houston, the former Australian defence chief who is leading the search coordination body, said, emphasising that further confirmation was needed.

Houston, the head of the search's Joint Agency Coordination Centre, said the Ocean Shield detection is the 'most promising lead so far' in the search for the missing Malaysia Airlines Flight MH370 wreckage in the southern Indian Ocean.

This image shows where two pings possibly from MH370 were detected along a tract where the plane is believed to have crashed into the ocean. Photo: Supplied

The first detection was held for about two hours and 20 minutes before contact was lost.

The second detection, made as the vessel back-tracked, was held for about 13 minutes.

"On this occasion, two distinct pinger returns were audible," air chief marshal Houston said.

"Significantly, this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder.

"Clearly, this is a most promising lead.

"In the search so far, it's probably the best information that we've had.

"I'm much more optimistic than I was a week ago."

The frequency of the signal, believed to be 37.5 kHz, is identical to the pulse sent by aircraft black boxes.

"We are encouraged that we are very close to where we need to be,"

The towed pinger locator deployed from the Australian defence vessel Ocean Shield has detected signals consistent with those emitted from aircraft black boxes, says former Australian defence chief Angus Houston. Photo: AP.

"The lead we've got at the moment is worth following through to the fullest extent."

However, Houston warned that while the lead was promising it wasn't confirmation that the plane had been found.

"We haven't found the aircraft yet and we need further confirmation - I really stress that," he said.

"There are many steps yet before these detections can be positively verified as being from missing flight MH370 ... it could take some days before the information is available.

Operators monitors TAC stations onboard a Royal New Zealand Air Force P3 Orion during search operations for wreckage and debris of missing Malaysia Airlines Flight MH370 in the southern Indian Ocean. Photo: AP.

"In very deep oceanic water, nothing happens fast."

The signals were detected just under 2000 metres apart but it was quite possible - because of the attenuation of audio under water - that the sounds came from the same source on the sea bed, Royal Australian Navy Commodore Peter Leavy said.

The priority is to reacquire the signal before Ocean Shield deploys an autonomous underwater vehicle that will attempt to find and photograph any wreckage on the sea floor.

Air chief marshal Houston said the vehicle's capability was stretched to its limit at the water depth of the current search zone.

"We're right on the edge," he said.

US Navy Captain Mark Matthews said the vehicle's imaging capability was just a few metres, "but sidescan sonar can extend another, maybe, 100 metres".

Air chief marshall Houston said the black box beacon's battery must be getting close to the end of its life.

"We're already one day past the advertised shelf life," he said.

"We hope that it keeps going for a little bit longer."

White floating objects spotted at the weekend by the Chinese had been checked and had no relationship to the missing plane.

Commodore Peter Leavy (right) of the Royal Australian Navy and Angus Houston (left), head of the Joint Agency Coordination Centre leading the search for missing Malaysia Airlines Flight MH370. Photo: AP.

MH370 disappeared on a flight from Kuala Lumpur to Beijing on March 8.

All 239 passengers and crew are presumed dead.

Ships, planes race to verify signals in hunt for MH370

Planes and ships were deployed to verify whether underwater signals are from the jet's black box, as the clock ticks on its battery life.

But experts have voice scepticism over the signals, which the Haixun 01 said were on a frequency used for the plane's flight data and cockpit voice recorders, and urged caution until better-equipped ships and air force planes reach the area.

The search area and the points at which the signals were detected.

Australia's JACC said that in total up to nine military planes, three civil planes and 14 ships took part in Monday's search operation.

Authorities said the Haixun 01 had twice picked up a signal -- once for 90 seconds on Saturday and another more fleeting "ping" on Friday a short distance away.

Houston said Haixun 01 was in waters about 4.5 kilometres deep, meaning "any recovery operation is going to be incredibly challenging and very demanding and will take a long period of time" if the plane is found there.

The Haixun 01 detected a weak signal just hours after picking up an initial 'pulse'. Photo: AFP.

- Time running out -

The Malaysia Airlines flight was on a flight from Kuala Lumpur to Beijing with 239 people aboard when it vanished, veering wildly off course for reasons that remain unknown.

A criminal probe has centred on hijacking, sabotage or psychological problems among passengers or crew, but there is no evidence yet to support any of the theories.

No debris has yet been found despite extensive aerial and sea searches, prompting authorities to focus more on undersea acoustic surveillance in hopes of finding the aircraft.

- Hope, scepticism over signal -

Australian aviation analyst Geoffrey Thomas said the Chinese signals were detected using a simple handheld device called a hydrophone which was lowered into the water on a probe from the side of a dinghy.

The device is designed for "shallow detection work" by divers and Thomas questioned whether it was capable of picking up a signal from 4.5 kilometres below the surface, saying it was the "the most low-tech solution you can think of".

"It certainly could pick up this signal, but it's picking it up at the extreme end of the range of detection," he told AFP, saying that while it was an improbable outcome, so was the disappearance of the plane.

"The Chinese could have stumbled on it, you can't discount it at all and I think the fact that Australia is sending ships to the area means they are not discounting it."

Wing commander Rob Shearer captain of the Royal New Zealand Air Force P3 Orion left, and Sgt. Sean Donaldson look out the cockpit windows during search operations for missing Malaysia Airlines Flight MH370 in the southern Indian Ocean, near the coast of Western Australia. Photo: AP.

Greg Waldron, Asia managing editor of Flightglobal magazine, was also sceptical that the Chinese ship had picked up a pulse from the black box.

"There have been a lot of false leads in this story and we need to be extremely cautious with any information that comes," he told AFP.