Search for MH370: Underwater vehicle Bluefin-21 deployed to find plane's wreckage

To sink underwater by the height of Britain’s tallest tower would still only cover 7 per cent of the descent to the floor of the Indian Ocean, 4,500 metres down, where the black boxes from Malaysia Airlines flight MH370 are presumed to lie.

Even at those 300 metre comparative shallows, all is dark. The furthest anyone has dived in a protective suit is a little over twice that. And only a handful of manned submarines have gone more than half the depth of the ocean being searched, underlining the scale of the challenge facing search teams.

Australia’s Prime Minister, Tony Abbott, said on April 11 that naval teams leading the international hunt were confident that they now knew the position of the black box flight recorder to within some kilometres.

But Angus Houston, the search co-ordinator, issued a statement saying there had been no major breakthrough. A possible signal detected on Thursday by Australian air force planes was ruled not to have been a fifth ping — diminishing hopes that the black boxes from the missing Boeing 777 were still signalling, beyond the cusp of their expected 30-day battery life. The joint agency co-ordination centre said a 46,713 square kilometre area of the Indian Ocean was still being searched for the plane, which went missing with 239 people aboard on March 8.

When transmissions from the underwater locator beacons cease, that search will become harder, but not impossible — Air France flight 447’s black boxes were found two years after signals stopped. But every ping detected allows search teams to triangulate further, rapidly narrowing the possible location.

The next likely stage, according to Prof Ian Wright, director of science and technology at the National Oceanography Centre, would be a coarse mapping of the sea floor using ships’ sonar. This would provide a base map for underwater robots. The same autonomous underwater vehicles found the AF447 wreckage at 3,900m. The ocean floor now being searched is 600m deeper still — a depth at which, in an apt analogy supplied by the US National Oceanic and Atmospheric Administration, the crushing weight of water is the equivalent of one person carrying 50 jumbo jets. This is at the limits of the Bluefin-21 robot, a 5.3 metre yellow torpedo-shaped machine which can create a high-resolution map of the seabed through sonar pulses.

While the manufacturers are confident it can work in such an extreme environment, William O’Halloran, of Bluefin Robotics, told the BBC: “To conduct surveys and searches in the subsea world, things move at about three nautical miles an hour — not very fast.” At that rate, it would take the Bluefin six years to map the search area.

Despite the greater depth, the comparatively flat Indian Ocean floor could be easier to search than the area around the mid-Atlantic ridge where AF447 was eventually found. Wright says: “That was a very young sea floor — it was very difficult to image that wreckage using sonar systems because of the rough topography and lack of sediment cover.” In the current search, the echo sounding systems should be much more effective in detecting anything unusual and providing a high resolution image. Wright says: “You would see wreckage or not. Then you would deploy an ROV.” The ROV is a remotely operated underwater vehicle that can film, scan and, crucially, pick up things from the seabed. It is tethered to a ship by an 8,000 metre cable, which not only holds the weight of the vehicle but powers it and contains fibre optics to transmit instructions and receive data.

The Remora, which can function at 6,000 metres, was used in the salvage of AF447 and other crashed planes, as well as the inspection of the Titanic. Its two hydraulic arms could either tie debris to a winch or place things in a sample basket, ideally including the flight data recorder and cockpit voice recorder.

While the robot takes care of business on the ocean floor, work remains hard on the surface. “It can run for about 24 hours. It’s a bit like being on a space mission — you’ve got a wall of TV cameras and controls. You’re talking about 50 tons of equipment and a team of six to eight people to run and maintain the ROV.” The impending southern hemisphere winter may further delay operations. The extent of the recovery will also be affected by just what damage was done on impact. While sections of fuselage have remained after some crashes — and the tailfin of AF447 was retrieved almost intact — other planes have been utterly destroyed. The investigation into Swissair flight 111, that crashed in 1998 off the coast of Nova Scotia, recovered around 2m fragments from relatively shallow waters. Decisions on recovery will be shaped by the human tragedy of MH370. The authorities are now working with the assumption that somewhere, possibly trapped within the wreckage or elsewhere in the ocean, are the remains of the 239 passengers and crew who took off for Kuala Lumpur to Beijing five weeks ago. In the wake of AF447, one of the questions that divided grieving families was whether the deceased should be left in the ocean. Just over half of the bodies were eventually brought to the surface. In the Swissair crash, most could only be identified by dental records or DNA traces.

The black boxes of a plane are made of superstrength components, designed to withstand extreme temperature, shock and the high pressure of the ocean depths — but Swissair investigators needed to recover wreckage to establish how fire had caused that crash. A cockpit voice recorder only stores the last two hours of conversation — long after the crucial manoeuvres apparently took place on MH370.

It takes two hours for the Bluefin-21 to reach the sea floor. At walking pace, it will then search for 16 hours, before taking another two hours to return to the surface. It then takes four hours to download the data the vehicle has detected.

The vehicle is equipped with side-scan sonar which transmits an active pulse. This produces a high-resolution three-dimensional map of the sea floor.

Meanwhile, ADV Ocean Shield detected an ‘‘oil slick’’ in the range of its search zone on Sunday, Mr Houston said.

However, it will be days before the origins of the oil can be investigated by experts on shore.

As many as 11 military aircraft, one civilian jet and 15 ships were searching an area about 47,644 square kilometres for the missing flight on Monday.

There have been no acoustic detections picked up in the underwater search area since Tuesday, JACC has confirmed.

The centre of the search zone is 2200 kilometres north-west of Perth, Western Australia, which has become the headquarters for the recovery operation.

Although the search is now in its fifth week, not a single piece of physical evidence has been located to confirm the whereabouts of MH370.

The Bluefin-21 Artemis autonomous underwater vehicle can operate at a depth of 4.5 kilometres and travels at a maximum speed of 4.5 knots, or less than nine kilometres an hour.

Prime Minister Tony Abbott gave the last indication of the underwater search zone, of about 2000 square kilometres, when speaking to Chinese media on Saturday.

Under optimal conditions the submersible can complete a 25-hour mission if it maintains a speed of three knots, according to its manufacturer, Bluefin Robotics.

It has been more than a week since the batteries from the flight’s two black box beacons was due to expire and six days since signals consistent with aircraft black box ‘‘pings’’ were last detected.

On Saturday in Beijing Mr Abbott said the search was still focused on an area measuring 40 kilometres by 50 kilometres in size.

He said search authorities had hoped to reduce the area to within one kilometre before deploying the Bluefin-21.

On Monday, Mr Houston stopped short of saying he believed the batteries were dead, but he has previously said the submersible would not be dropped to the ocean floor until there was absolutely no hope the black boxes would emit another signal.

Malaysian Airlines flight MH370, with 239 people on board, vanished after mysteriously changing course during a flight from Beijing to Kuala Lumpur on March 8.

It is hoped the plane’s two black boxes: a flight data recorder, and a cockpit voice recorder will hold vital information about what happened in those final hours.

Earlier today Malaysian authorities revealed they were uncertain about what to do with the black boxes from Flight 370 if they are located and brought to the surface.

The country’s Attorney-General, Abdul Ghani, has flown to London to consult with the United Nations Civil Aviation Organisation and other experts about who should get custody of the boxes.

Although Malaysia is the head of the investigation under international law, the government has called on international experts from countries including the United States and Britain to assist with the investigation.

As the suspected final resting place of MH370 falls within Australia’s search and rescue zone, Australia has been the lead agency for coordinating the search Indian Ocean search effort

Monday 14 April 2014

http://www.thehindu.com/opinion/op-ed/robots-search-sea-bed-for-mh370/article5908527.ece

http://www.smh.com.au/national/search-for-mh370-underwater-vehicle-bluefin21-deployed-to-find-planes-wreckage-20140414-36n2k.html