MH370: what are the obstacles in the search for Malaysia Airlines plane?
Search effort in southern Indian Ocean faces a lengthy and technically complicated task in stormy weather conditions
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Jon Henley
@jonhenley
Last modified on Tuesday 3 May 2016 08.29 EDT
Even if the two unidentified objects shown on satellite images floating in the southern Indian Ocean are debris from the missing Malaysia Airlines plane, finding them could prove to be a long and difficult process that may rely on good luck as much as on advanced technology, oceanographers and aviation experts warned on Thursday.
If the objects are recovered, locating the rest of the Boeing 777 on the ocean floor could turn out to be harder still. And if the fragmented and scattered remains can eventually all be collected and pieced together, working out exactly what happened to flight MH370 may be the toughest job of all.
"You know, we may never actually see anything," said David Learmount, operations and safety editor at aviation news specialists Flightglobal. "It may simply not be feasible. That was actually my first thought when I heard of the flight's disappearance: we may never find it. We may never know what happened."
Poor conditions
The obstacles facing the Australian-led search operation, currently involving four aircraft and up to seven ships combing a 23,000 sq km area of ocean some 2,500 km south-west of Perth, are immense - starting with the fact that the satellite images on which the two objects were spotted date from four days ago, and weather and sea conditions in the area are hardly favourable.
"Those satellite images had to be gone over by hand," said Simon Boxall of the National Oceanography Centre in Southampton. "That takes a lot of experts a lot of time. But the issue is that there are very strong currents where the flotsam was located. The Antarctic circumpolar current runs at around one mile an hour, which may not sound a lot but in ocean terms is very fast. In four days, those objects could have travelled 100 miles."
That is in calm weather conditions, which these are not. Australia's Maritime Safety Authority suspended the search operation as darkness fell on Thursday with no sightings reported, but Australian air force pilots said rough seas and high winds added up to "extremely bad" weather conditions. In stormy weather, waves in that part of the Indian Ocean can reach six metres.
"We're talking about the Roaring Forties," Learmount said. "There are continual strong westerly winds, a big swell, often high waves as well. Visibility is poor. But radar is of little help because it struggles in rough seas. Infrared is no good because the objects will be the same temperature as the water. We really have to eyeball these objects - but eyeballs struggle in poor visibiity. It may be days before we find whatever the satellite saw."
Large pieces of floating debris from a crashed plane - if that is what it is - could also break up in heavy seas, other experts note. Fragments could quickly spread over an area covering tens of square kilometres, with semi-submerged material travelling at a different rate than objects floating on the surface. Professor Alexander Babanin, director of the Centre for Ocean Engineering, Science and Technology at Swinburne University of Technology in Australia, said that if an object is suspended "it could be carried quite some distance, perhaps even more so than by waves, because ocean currents can be stronger than wave-induced currents".
Worse for the searchers than the flotsam fragmenting, Boxall said, would be if it simply sank. "Are these objects still afloat?" he asked. "What keeps something afloat, a wing or part of the fuselage, say, is air trapped inside it. Particularly in bad weather and sea conditions, the chances of that air escaping are really quite high."
Satellite images of the two objects spotted. Photograph: UPI/Landov/Barcroft Media
Undersea issues
Assuming the flotsam is eventually spotted and identified as belonging to flight MH370, it will be collected by a surface ship guided from the air. Then begins the task of locating the aircraft's remains on the ocean floor. "Whatever is found on the surface will be a very long way from wherever the plane fell," Learmount pointed out, "which will be some distance from whatever's on the ocean floor. And any deepwater rescue would need good weather, which means - if you're lucky - summer. Right now we're heading towards winter."
According to David Gallo, director of special projects at the Massachusetts-based Woods Hole Oceanographic Institution, the remote area of the southern Indian Ocean where the search operation is focused lies above a part of the south-east India ridge, which runs from east to west and slopes down from a peak that is roughly 2,500m (8,200 ft) beneath the surface to a depth of around 4,000m. Gallo said that, by deep-sea survey standards, the terrain is relatively straightforward and research submarines would be able to operate without too much difficulty.
"Once a piece of the debris is found - if it did impact on the water - then you've got to backtrack that debris to try to find the 'X marks the spot' where the plane actually hit the water, because that would be the center of the haystack," Gallo told CNN. "And in that haystack, you're trying to find bits of that needle - in fact, in the case of the flight data recorders, you're looking for a tiny little bit of that needle."
Once that "X" has been worked out - itself a process fraught with potential errors and miscalculations - accident investigators will send down autonomous underwater vehicles (AUVs) fitted with sonar to scan the sea floor or with high-resolution cameras to compile a detailed picture of the area. AUVs, also known as submersibles, which could take up to a month to be transported to the area, could be critical in locating the plane's tail section and the vital black box containing the digital flight data - particularly so because, while the box's data can still be recovered years after a crash, its electronic locator or pinger stops sending out signals after about a month.
The flight data recorder registers information for the first 25 hours of flight and could yield priceless information. The plane's cockpit voice recorder, though, may prove less useful: it records for two hours and then resets itself and records over the top of the previous two hours' recording. In the case of flight MH370, the plane is thought to have flown for several hours after the critical events took place and would have been recorded in the cockpit.
Sorry, your browser is unable to play this video. Lessons from past crashes
Two recent air crashes over water illustrate the daunting task facing the investigators. TWA flight 800 exploded in mid-air soon after taking off from New York's John F Kennedy airport on 17 July 1996 on a scheduled flight to Rome via Paris, killing all 230 people on board. Reconstructing exactly what happened was vital to disprove conspiracy theories, one of which was that terrorists may have fired a rocket at the plane.
Wreckage scattered in thousands of fragments over some 75 sq miles of the Atlantic Ocean floor took US navy and other divers more than 1,600 hours to find and collect. Strewn along the flight path they first found a wing section, then the nose, the rest of the wings and the aircraft's tail and engines. After painstakingly reconstructing all the wreckage that they had found, and finding no evidence that the plane had been hit by anything from the outside, the accident investigators concluded - in a report issed three years after the crash - that the Boeing 747 broke into pieces off Long Island following an explosion caused by an electrical short circuit that detonated the fuel tank.
Air France flight 447, which disappeared en route from Rio de Janeiro to Paris on 1 June 2009, was an even more complex investigation. Although the Brazilian navy found and removed the first major wreckage and two bodies from the sea within five days, it took four searches and nearly two years to find the rest of the wreckage of the plane, an Airbus A330, located up to four days' sailing from the nearest port and more than 3,000m beneath the surface of the Atlantic Ocean.
The voice and flight data recorders were not recovered until May 2011 in an operation that was co-led by Gallo, and the final accident report, which concluded that the plane crashed following a series of errors by its pilots in reponse to a variety of technical problems, was only published in July 2012.
Learmount said that while the undersea terrain appears easier in the southern Indian Ocean than where Air France 470 went down, the weather and sea conditions will almost invariably be considerably worse. "They found AF470 by basically trawling the ocean floor," he said. "That requires reasonable conditions. Once again, this is the Roaring Forties. You never get really good conditions in the Roaring Forties."