Some 16 months before black box recorders from Air France Flight 447 were found on the Atlantic Ocean floor in 2011, investigators already had a pretty clear picture of the crash.
Examination of floating wreckage indicated the Airbus A330 had hit the ocean intact, belly-down and at high speed, according to preliminary reports the French accident inquiry published in 2009. The cabin was fully pressurized, the pilots weren’t trying to land and members of the cabin crew weren’t buckled into their seats.
Modern air accident investigations depend heavily on the wealth of information stored in the plane’s flight data recorders. But fragments of wreckage also can give a remarkably accurate portrait of the event, thanks to forensic evidence left behind by the violence of a crash. If debris found on the coast of Reunion island, called a flaperon, turns out to be from Malaysia Airlines Flight 370, it may offer fresh clues into how the plane disappeared 16 months ago with 239 people on board.
“That’s the difference between a casual observation and forensic analysis,” Geoffrey Dell, a professor specializing in accident investigation at Australia’s Central Queensland University, said by phone from Adelaide. “You need to look at what evidence this piece of wreckage tells us, and how that fits with what we already know.”
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Every accident investigation yields fresh insights into the tell-tale signs left by a crash. When investigators recovered a floating piece of Air France Flight 447’s wing in 2009, dents on its surface showed the landing flaps were retracted when it crashed. That told investigators the pilots weren’t trying to carry out a water landing.
Examination of filaments from the cockpit alert light-bulbs in the 1996 crash of TWA Flight 800 off New York’s Long Island suggested they weren’t lit at the time of the incident, illustrating how little warning the pilots had of what was happening.
The impact of Swissair Flight 111 hitting the water in a 1998 accident off the coast of Nova Scotia froze the cockpit attitude indicator in place, suggesting that the plane had its nose down and had rolled almost upside down when it entered the water.
In this case, the specific way the wreckage buckled may give a clue to the sorts of forces that tore it off the plane, Dell said. That could suggest whether the plane broke up when it hit the water or in mid-flight, which could indicate what size of objects investigators should be looking for: A higher-speed crash would create smaller pieces of debris than a lower-speed one would.
“Even though this thing has been floating around in salt water for 16 months, I’d have thought some electron microscope examination would tell us something,” he said. “We could find out what type of overload failure it was, or whether there’s any other impact damage.”
Such data could also help resolve questions about the speed and angle at which Flight 370 hit the ocean. The Australian Transport Safety Bureau, which has led a sonar hunt of more than 50,000 square kilometers of the ocean floor, has spent 10 months gradually working outward from a zone where it’s thought the 777’s fuel ran out.
That’s been based on the assumption that the plane crashed at a fairly steep angle from the point of fuel exhaustion. If it descended at a more shallow pitch, it may have traveled further out than ships are currently searching.
“Any new evidence will be used to further inform and refine ongoing search efforts,” Australia’s Joint Agency Coordination Centre, which is leading the search effort along with the bureau, said in an e-mailed statement.
Of course, one piece of wreckage on its own doesn’t yield a lot of information – and there already have been plenty of false alarms in the investigation.
Search crews scanned an 850-square-kilometer stretch of seafloor last year after an underwater microphone picked up pings that initially were thought to have come from the flight recorder’s emergency beacon. That theory was later ruled out.
In March, Fugro NV, the Dutch survey company undertaking most of the sonar survey, spotted a region of hard objects resembling an aircraft debris field. They later turned out to be volcanic rocks.
“Until they get the data and confirm the component, we just don’t know for sure,” Peter Marosszeky, a lecturer at Sydney’s University of New South Wales who specializes in air accidents, said by phone. “I’m really not too sure what it is.”
Still, the discovery of the debris on Reunion gives hope that other parts may turn up in the vicinity, according to Charitha Pattiaratchi, a professor of oceanography at the University of Western Australia.
The part likely was floating in the top two meters of seawater and would have traveled first north and then west on a path south of the equator, he said. Circular ocean currents would have sent the wreckage anticlockwise.
“The location and the timing, it’s entirely consistent with modeling that we did 18 months ago,” Pattiaratchi said by phone from Perth. “It gives us a little bit more hope that more debris will turn up in that whole region – Reunion, the Seychelles, Madagascar.”