MH370: Where is the Debris?

When Australia called off the surface search for Malaysia Airlines Flight 370 on April 28, Prime Minister Tony Abbot explained that “It is highly unlikely at this stage that we will find any aircraft debris on the ocean surface. By this stage, 52 days into the search, most material would have become waterlogged and sunk.”

But would the debris really have sunk? Modern aircraft are made of metal, composites, and plastic, materials that do not get waterlogged. If, as the Australian Transport Safety Board (ATSB) believes is most likely, MH370 ran out of fuel and then crashed, it would have been moving at hundreds of miles per hour when it hit the sea. Much of the resulting debris would have settled down through the water column, but innumerable pieces would have remained afloat. After Air France Flight 447 went down in the middle of the Atlantic in 2009, searchers found some 3,000 pieces of debris scattered across the surface.

With the passage of time, the absence of MH370 debris becomes increasingly puzzling. Recently Emirates Airlines CEO Tim Clarke expressed frustration over the ATSB analysis of the plane’s fate, saying: ”Our experience tells us that in water incidents, where the aircraft has gone down, there is always something.” This is true. As far as I know, there have been no cases where a commercial airliner has crashed into the sea and no parts were recovered, even if the crash occured in an unknown location far out in the middle of the ocean, as MH370’s presumably did.

Consider the fate of the Boeing 377 Stratocruiser “Clipper Romance of the Skies,” which disappeared on the first leg of a planned round-the-world flight somewhere between San Francisco and Hawaii in 1957. An aircraft carrier was dispatched and found floating debris six days later, halfway between its origin and destination and 90 miles from its planned track, some 1,000 miles from the nearest land.

The area where MH370 is now believed most likely to have gone down is a bit further out to sea, some 1,500 miles southwest of Perth. But far more assets were been deployed in the search, including satellite, ships, and land-based aircraft. Indeed, the area was one of the first to be searched for surface wreckage back in March. 

Still, it’s easy to imagine that even pieces of debris might have been overlooked in the vastness of the sea, especially given the uncertainty surrounding the plane’s crash site. That’s why many have long thought that the first hard proof of the plane’s fate might well take the form of flotsam washing up on a beach somewhere.

Despite Tony Abbott’s assertion, the ATSB remains open to this possibility, stating on its website:

“The ATSB continues to receive messages from members of the public who have found material washed up on the Australian coastline and think it may be wreckage or debris from MH370. The ATSB reviews all of this correspondence carefully, but drift modelling undertaken by the Australian Maritime Safety Authority [AMSA] has suggested that if there were any floating debris, it is far more likely to have travelled west, away from the coastline of Australia. It is possible that some materials may have drifted to the coastline of Indonesia, and an alert has been issued in that country, requesting that the authorities be alerted to any possible debris from the aircraft.” 

It’s not clear why the AMSA believes that the debris’ main landfall would be to the north of the presumed impact area. Pioneering ocean-current researcher Curtis Ebbesmeyer, a retired professor of oceanography at the University of Washington, says that the South Indian Current should have been carrying MH370’s wreckage eastward, at a rate of five to ten miles per day. That implies an arrival window on the beaches of Western Australia of between mid-June and late September.

Computer models of drift patterns suggest a similar conclusion. I created the animated gif below  from the website Adrift.org.au. Another website that yields similar results is Ocean Motion (my thanks to Brock McEwen for turning me onto that one).

Ebbesmeyer says that if we assume that the impact generated a million fragments, and that one-tenth of one percent of the fragments reach the coast, “that would give 1000 objects on the shore, or one per mile of Australian coastline. Not too bad odds.” Especially considering that beachcombers have been especially vigilant about collecting the world’s most famous pieces of flotsam. Back in April, a hunk of aluminum that washed up on an Australian beach generated headlines for days, before experts from the ATSB determined that it had not come from an aircraft (the ATSB has yet to reveal what it actually came from).

As I write this, warm weather is coming to Western Australia, and with every passing weekend more and more people are going to the beach. Earlier this month, on October 11 and 12, a nonprofit organization called the Tangaroa Blue foundation held its annual Western Australia Beach Cleanup. Some 1500 volunteers combed 130 beaches up and down the western coast collecting plastic rubbish and other debris. The goal of the event is to keep the coastline litter-free clean, but this year volunteers were well aware that they might well stumble upon evidence that could help solve history’s most puzzling aviation mystery. “When [MH370] first happened, and they said where they thought it went down, I said to myself, ‘Oh crap,” because I knew this is where it would come,” says event organizer Renee Mouritz. With those drift patterns in mind, the organization set up an informal protocol to pass along reports of any suspected MH370 debris to the AMSA. But so far, Mouritz says, “nobody has fed anything back to us.”

There’s an old saw that’s oft quoted in discussions of MH370: “The absence of evidence is not evidence of absence.” But from a Bayesian perspective, the absence of data is itself data. If the plane crashed into the Indian Ocean, it should have created many pieces of debris, and some of those pieces should have wound up on a shore by now. The more time passes without that happening, the greater the possibility that the plane did not go into the ocean.

This idea makes some people extremely uncomfortable. Indeed, some people insist that we know that the plane is in the southern ocean because Inmarsat’s frequency data tells us that it must be. They argue that there are any number of reasons why the debris cannot be found. One is that the plane might have ditched gently enough to have remained intact, a sort of deepwater Miracle on the Hudson, though this obviously could not be the case if the ATSB’s default flew-south-on-autopilot-until-it-ran-out-of-gas scenario is correct.

Tim Clarke, for his part, appears less than completely convinced by the frequency data. As he puts it, “We have not seen a single thing that suggests categorically that this aircraft is where they say it is.” As time goes by without debris turning up, we can expect sentiments like Clarke’s to become increasingly common.

UPDATE: My assertion that no commercial plane crash at sea prompted Twitter use @fxnighttrader to alert me to the case of the Varig Boeing 707-323C freighter which disappeared off the coast of Japan in 1979. The plane had taken off from Narita and was 30 minutes into a planned flight to Rio de Janeiro when it ceased radio contact and was never heard from again. Intriguingly, among the cargo were 153 paintings by contemporary artist Manabu Mabe, which were valued at $1.24 million, or about $4 million in today’s money. @fxnighttrader writes, “This plane went into the ocean less than 200 miles from Japan and no piece was ever found,” but I think it would be more accurate to say that the plane vanished and no one ever figured out why.

UPDATE 2: Brock McEwan reports, “The ATSB seems to have just removed from their site all reference to the AMSA drift analysis.”