The wreck of missing Malaysian Airlines flight MH370 — if it is found — could be preserved "like a time capsule" because of the depth, stillness and temperature of waters in the southern Indian Ocean, reports ABC News.
The man who co-led the search for Air France 447 — which crashed in the Atlantic Ocean in 2009 — says if MH370 is at or near the bottom of the sea, the wreckage and indeed bodies could be largely preserved, and still give investigators vital clues as to why the plane disappeared so far off course.
"It can be a very quiet place with very little oxygen," US oceanographer David Gallo said.
"At the surface it's not the same thing, so the deep ocean can be like a time capsule that preserves everything."
The Air France plane was in water nearly four kilometres deep for nearly two years before searchers finally found it and retrieved the flight data recorder and cockpit voice recorder.
Both recorders were still in good enough condition to shed light on the plane's final minutes, despite having been immersed at such depth for so long.
"Even if water gets in there they have ways of getting bits of information off," Dr Gallo said.
"Now in this case [MH370] it's a bit different, because the plane was flying for some seven hours, and I don't know what kind of information would be left on the black box. It keeps rewriting itself.
"I think the voice cockpit recorder … records over itself after two hours."
Australian oceanographers say the Indian Ocean in the area of the current search for MH370 — which began on Monday — includes several volcanoes and ridges, and drops to around 5km in depth.
"There's an awful lot of pressure — 6,000 metres would be 9,000 pounds per square inch roughly," Dr Gallo said.
"That's an incredible amount of pressure for them to withstand. But they may well have done it."
But even finding the black boxes at all could prove impossible, given they are housed in the plane's tail, which often falls off in a crash.
"Most of them come loose because they're very heavy. The mount rips loose and off they go," he said.
Even so, Dr Gallo says the plane's fuselage or debris field can still give investigators a wealth of information, without the black boxes.
"Say you get into the cockpit, look at the settings. You could look at the actual airframe itself — about how pieces are bent or torn or scarred or burnt," he said.
"It's just like a crime scene … an underwater crime scene. We did this with Air France. We took 85,000 single images of that plane so that the forensic team could actually see it the same way it would be on land.
"So they could point to something and say: 'That's an engine, that's a landing gear. What does that tell us when we see that the landing gear is bent or the flap is up or down?'"
And although the Air France plane broke into pieces on impact, the bodies of many passengers were found largely intact, giving investigators more clues.
Read more of this report from ABC News (Australia).