IN A major development in the search for MH370, Angus Houston has confirmed the Ocean Shield has detected signals consistent with aircraft black boxes, describing the lead as the most promising yet.

Air Chief Marshal Houston called the development significant, saying “this is the most promising lead, probably in the search so far, it’s probably the best information we’ve had”.

The search coordinator told reporters more signals have been detected by a towed pinger locator deployed by the Australian vessel Ocean Shield.

“Today, I can report some very encouraging information which has unfolded over the last 24 hours,” he told reporters in Perth.

Air Chief Marshal Houston said the signals are “consistent with those emitted by aircraft black boxes.”

media_camera The towed pinger locator on the deck of the Australian vessel Ocean Shield.

“Two separate signal detections have occurred within the northern part of the defined search area.”

The first was held for more than two hours, the second for about 13 minutes.

“On this occasion, two distinct pinger returns were audible.”

He said both would be consistent with transmissions from the flight data recorder and the cockpit voice recorder.

media_camera This map shows the site where signals consistent with a black box were detected.

Air Chief Marshal Houston described the find as “the most promising lead” yet.

“We haven’t found the aircraft yet,” he stressed, arguing further confirmation is needed.

Air Chief Marshal Houston said the position of the signals would need to be fixed before an autonomous underwater vehicle ‘Blue Fin 21’ could be deployed to locate wreckage.

“The area in which the signals have been received has a depth of approximately 4,500 metres,” he warned, adding it is also the “limit of capability of the autonomous underwater vehicle.”

media_camera A crew member reads through his notes onboard a RNZAF P3 Orion.

He further argued it could take time to establish with certainty if the detections are from MH370.

“You’re right, the life of the batteries must be getting somewhere close to the end of life,” he admitted, when asked about the black box.

“We’re already one day past the advertised shelf life. We hope that it keeps going for a little bit longer,” he said.

HMS ECHO ENTERS SEARCH ZONE

CNN reports that British navy ship HMS Echo has entered the zone where Chinese patrol vessel Haixun 01 picked up two underwater signals only two kilometres apart.

The Australian vessel Ocean Shield is expected to reach the search area later today or tomorrow.

Both the Ocean Shield and HMS Echo have deep-sea listening equipment.

media_camera A crew member reads through his notes onboard a RNZAF P3 Orion during search operations for wreckage and debris of missing Malaysia Airlines Flight MH370.

Twelve aircraft and 14 ships will be part of today’s search effort, covering an area of approximately 234,000 square kilometres.

Weather is predicted to be good, with afternoon showers not expected to affect the search.

SEARCH: MH370 ‘flew around Indonesian airspace’

THEORY: Did MH370 fly to Diego Garcia?

CNN is also reporting that Flight MH370 may have flown around Indonesian airspace on the night it disappeared, in what may have been a deliberate attempt to avoid radar detection.

media_camera MH370: ships race toward signals

A senior Malaysian government source said the missing jet made the detour after it had left the range of Malaysian military radar.

media_camera Flight MH370: Ships race toward signals

CHALLENGE OF THE SEARCH

IT will be “incredibly challenging” to retrieve MH370’s black box from a stretch of Indian Ocean where a Chinese vessel may have finally located the missing airliner.

The section of ocean, about 2000km northwest of Perth, in which the Haixun 01 has picked up two possible signals from the black box of the missing Boeing 777-200ER is about 4500m deep.

If the signals are proven to be from the airliner Air Chief Marshal Houston said it would be “very demanding” to retrieve the black box recorder and other wreckage.

“The water in which the Haixun 01 is working at the moment is very, very deep,” he said.

media_camera New leads ... an Australian Air Force Orion plane taking off from Pearce Airbase in Bullsbrook, 35 km north of Perth. Picture: Tony Ashby

“I think it is in the order of 4500m and that is incredibly deep. Any recovery operation is going to be incredibly challenging and very demanding and will take a long period of time,” he said.

According to James Cook University marine geologist Dr Robin Beaman, the search area forms part of the Perth Abyssal Plain — a vast stretch of flat, muddy ocean bottom.

It lies about 60km east of the Brouwer Trough, an ocean trench that drops as low as 5000m below sea-level.

While relatively free of geological features that would make it difficult to access the black box flight recorder or aircraft wreckage, Dr Beaman said the depth would present problems.

media_camera An observer looks out a window onboard a RNZAF P3 Orion during the search operations for missing Malaysia Airlines Flight MH370 in Southern Indian Ocean on April0 4, 2014.

“The challenge is that it’s a lot deeper than anywhere they have been looking before,” he said.

“It’s right at the bottom of a very large basin.”

For example, 4500m is the maximum depth at which a Bluefin-21 autonomous underwater vehicle carried by the Ocean Shield can operate.

The 6.4 metre-long robot is an invaluable tool that is capable of staying submerged for 25 hours at a time, deploying its sensors to search and map 40 square miles of sea floor per day.

However, Dr Beaman said recovery teams would be aided by a good understanding of the area, with an Australian research team mapping it as recently as 2011.

“Our knowledge of this area is as good as anywhere in this stretch of ocean,” he said.

media_camera Big guns ... a Chinese Ilyushin IL-76 aircraft flies over Perth returning from search operations. Picture: AP

Originally published as MH370: ‘Our most promising lead’