Australian oceanographers are trying to solve one of the aviation industry's greatest mysteries within a mystery: if MH370 did plunge into the Indian Ocean, why have no confirmed pieces of debris washed ashore?
The inability to find a single piece of the wreckage has confounded experts since the Boeing 777-200ER mysteriously disappeared on March 8, 2014, with its transponder switched off.
The original ocean drift models released by the government suggested the first debris from the plane would come ashore in West Sumatra, Indonesia, after about four months. That would have been July.
The difficulty facing oceanographers is that they don't have a definitive "splash point" – the place the aircraft plunged into the ocean – to pin their calculations to.
It is not clear which "splash point" the government used to come up with that calculation, but University of Western Australia oceanographer Professor Charitha Pattiaratchi says it must have been wrong.
"That's an impossibility," Pattiaratchi says. "The currents would never take debris to Indonesia."
SEVENTH ARC
UWA used several potential splash points in its calculations, all of which are on a portion of something called the seventh arc, which represents the plane's presumed flight path.
All of the UWA calculations have the debris ultimately moving east or west from the crash site, which would mean debris should have washed up on the Western Australian coastline by about September last year.
Given it is now March, oceanographers have been thinking through why that hasn't appeared to have occurred.
One possible explanation is that it has occurred; but the abundance of junk in the ocean has meant that nothing that can conclusively be identified as having come from MH370 has been found.
Pattiaratchi says two cyclones that went through the search area not long after the plane disappeared may have interfered – or quickly submerged – objects that might have otherwise drifted towards the coast.
Another explanation is that the plane did not disintegrate on impact, as expected. Rather, if the fuselage – the aircraft's main body – sunk relatively intact, there would be less debris.
DRIFT MODELLING
The Australian Transport Safety Bureau, which is the body responsible for the underwater search, is due to release reworked drift modelling soon.
David Griffin, the CSIRO oceanographer who heads the MH370 drift model task force, says tidal movements in the search zone are likely to "stir" debris in circular movements, where they might not reach land.
"That's entirely consistent with the lack of debris coming onshore," he said.
The tidal movement contrasts with the east-west/west-east movements nearer the equator that would quickly carry debris to shore.
The new drift model will rely on updated analysis of where the plane may have hit the water.
While there is some hope that finding debris would help locate the plane, and with it, its flight recorders, the time that has now elapsed might make drift models problematic.
If debris can be located shortly after a plane crash, oceanographers would likely be able to "back track" and locate the main wreckage using their knowledge of winds and tides in the area.
This happens regularly in environmental incidents. Oceanographers are often able to trace pollution that has washed up to a specific passing vessel, which can then be held to account.
Now that more than a year has passed since MH370 went missing, oceanographers would likely only be able to identify a large area that the plane was thought to have crashed in.
"The longer it goes the larger the search location would be," Pattiaratchi said.
The underwater search of the 60,000 square kilometre priority zone is scheduled to finish in late May. If the debris field has not been located by then, authorities would need to commit further funding to search lower priority areas or call off the search.
