KUALA LUMPUR (AFP) - Even if searchers are able to miraculously pluck Malaysia Airlines flight MH370's "black box" from the depths of the vast Indian Ocean, experts say it may not solve one of aviation's greatest mysteries.
Planes and ships with state-of-the-art tracking equipment are hunting for any trace of the passenger jet, which Malaysia said crashed into the forbidding waters after veering far from its intended course.
They face a huge challenge locating the Boeing 777's black box, which holds vital clues to determining what caused the plane to vanish after it took off from Kuala Lumpur en route to Beijing on March 8.
But experts believe the flight data recorder and cockpit voice recorder may not yield answers on the riddle of how and why the plane changed its path an hour into the flight, and embarked on a baffling journey to the southern reaches of the Indian Ocean.
The data recorder details the aircraft's path and other mechanical information for the flight's duration, and "should provide a wealth of information", US-based aviation consultancy firm Leeham Co said in a commentary.
But the cockpit voice recorder - which could reveal what decisions were made by those at the helm and why - retains only the last two hours of conversations before a plane's demise.
That means potentially crucial exchanges surrounding the initial diversion, which took place halfway between Malaysia and Vietnam, will be lost.
"Clearly, it won't reveal anything that happened over the Gulf of Thailand - this will have been overwritten by the end of MH370," it said.
Leeham added that it also remains to be seen whether the cockpit recorder will contain anything pertinent about the plane's final two hours, when it is believed to have either ditched or run out of fuel.
Malaysian Prime Minister Najib Razak said on Monday that flight MH370 had gone down in the Indian Ocean with its 239 passengers and crew, citing new satellite data analysis.
But its exact location and the circumstances of its diversion remain a mystery. No distress signal was ever received.
Three scenarios have gained particular traction: hijacking, pilot sabotage, or a sudden mid-air crisis that incapacitated the flight crew and left the plane to fly on auto-pilot for several hours until it ran out of fuel.
Malaysia has said it believes the plane was deliberately diverted by someone on board.
But with the travelling public and aviation industry hanging on every twist in the drama, no firm evidence has emerged from the Malaysian investigation to support any of the theories circulating.
British aviation expert Chris Yates said that even if the black boxes are found, "it seems unlikely that we will get that answer" of why the plane ended up thousands of kilometres off course.
"We still have no idea as to the mental state of the pilot and co-pilot, we have no idea if somebody managed to get into the cockpit to seize the aircraft, and we've certainly had no admissions of responsibility since this whole episode started," he told BBC television.
"It is a mystery like no other."
Debris has been sighted far off Australia's west coast but an international search effort has been unable to retrieve any for confirmation, and wreckage could have drifted hundreds of kilometres from where the plane crashed.
"As investigators, we deal with physical evidence and right now we don't have any physical evidence to work with," Mr Anthony Brickhouse, a member of the International Society of Air Safety Investigators said.
The batteries powering the locator signal of the black boxes will run out in less than two weeks.
A US device capable of detecting that signal even on the ocean floor was being sent to the scene, but weather and treacherous sea conditions have hampered the effort to pinpoint the black box location.
Mr Paul Yap, an aviation lecturer at Singapore's Temasek Polytechnic, said that if the black box is not found, "chances are we are never going to find out what really happened".
"With the new satellite data, I think we can say it is a chessboard," he said of the wide search area.
"The question now is to find which grid on that chessboard to focus on, where the black boxes are." Straitstimes
News Sky
By Dominic Waghorn, US Correspondent
An American scientist who led the search for wreckage after the Air France crash in 2009 has said time is running out to find the missing Malaysia Airlines plane.
Colleen Keller, who helped scour the Atlantic Ocean for flight AF447 after it disappeared en route from Rio de Janeiro to Paris, said identifying the search area was a major challenge.
She fears the chances of doing the same for the Malaysian airliner are now dwindling.
"We're going to need some significant leads to find it," said Ms Keller, who worked as an analyst for Metron, a scientific consultancy for the US Navy.
Brazilian Navy sailors pick a piece of debris from Air France flight AF447 out of the Atlantic Ocean
It took two years to find the Air France plane's black box recorders
"I think the search area is so big. I'm certainly hoping the criminal investigation will yield some motives that will steer us in the right direction."
The breakthrough in the Air France investigation came when US underwater drones discovered the wreckage of the aircraft off the coast of Brazil.
Based at Woods Hole Oceanographic Institution in Cape Cod, the unmanned yellow submarines can spend hours underwater scanning the ocean floor.
Working in pairs, the drones dive as low as 6,000 metres below the surface.
Flight MH370
The plane disappeared mid-way through a flight from Kuala Lumpur to Beijing
The vessels cruise above the ocean floor using a lawnmower-style pattern, moving 10 miles one way and 10 miles back on routes pre-programmed before they are dropped into the sea.
A picture then emerges of the seabed and what is lying on top of it.
It took months of searching in 2010 and 2011, but the drones' eventual discovery allowed divers to salvage the plane's wreckage and, crucially, its black box recorders.
The Air France plane issued emergency signals as it went down and left debris on the surface of the ocean, giving a starting point for the search.
Even so, it took two years before the plane was found.
Oceanographical engineer Mike Purcell, based at Woods Hole, told Sky News the complete lack of information was dampening hopes of discovering answers about the fate of flight MH370.
"It's possible we'll never find out what happened," he said. "I think there are just so many unknowns right now."
The Remus 6000 subs could be the best chance of solving the mystery.
For now, they lie on harnesses in port, as operators wait for crucial clues about where to begin their search.
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