31 March 2014

On Running Amok

Currently it seems that the remains of the Malaysia Airlines Boeing 777, flight MH 370 from Kuala Lumpur to Beijing on 8 March, are in the southern Indian Ocean. Matthew Parris in an article, The flight swallowed up by a beautiful hell, in The Times (£) on 29 March described from personal experience the extreme nature of the areas which have been searched.  Annexed below are the expert opinions of Dr Philippe Blondel of the Department of Physics, University of Bath, on the difficulties of looking for lost aircraft using side scan sonar.

The first flight I ever made was from Penang to Singapore on a Douglas DC-3 belonging to Malayan Airways, Malaysia Airlines’ predecessor but several. The formal British colonial involvement, direct and indirect, with Malaya lasted from 1824 to 1963, although it now seems far less well-remembered than the experience of India. Wikipedia has a list of about 60 English words of Malay origin, “Loan words from Malay in English”, although some of these loans seem to be more taken for granted than others, for example: compound (enclosed group of buildings), gingham, gong, ketchup, launch (boat), sago, sarong. Amok, usually preceded by run or running, is a common useage, as is its Norse companion, berserk. It also appears as amuck and amock, all three words according to the Oxford English Dictionary have been used as a noun or an adverb, stemming from the Malay amuq, since the late 18th century.

Someone has provided Wikipedia with a detailed account of amok, which is, according to the article, a recognised psychiatric condition.

ANNEX by Dr Philippe Blondel of the Department of Physics, University of Bath for the BRLSI 

The news are still coming in from the search for missing Malaysia Airlines flight MH370, and two weeks after the catastrophe, there is still no trace of the plane or its passengers and crew. Debris were sighted by satellites in the Southern Indian Ocean, several thousands of kilometres south of Australia and far from the intended route, but there has been no other indication since. How else can modern instruments help the search? Debris at the sea surface will be hard to find by the search parties, combing several hundred thousand square kilometres of some of the most challenging places in the ocean. Speaking from experience, I know how hard it can be to see objects in waves several metres high, from the bridge of a ship subject to the weather typical of the “Roaring Forties”. But even if tell-tale signs are still visible at the surface, two weeks after the catastrophe, most would have sunk several kilometres down to the seabed.

The best search tools are sonars, using focused beams of ultrasounds to probe all the way to the seabed. The first priority remains to identify with certainty the site on the seabed. Traces at the surface, from debris to oil patches, would drift with the currents and the prevailing wind patterns, and they need to be traced back to a potential source. Anything sinking from this source would then be affected by underwater currents, possible implosions at different depths, scattering over a large debris area and being affected in different ways by bottom currents. This part of the search is likely to take several weeks. Mapping the site itself can take several weeks or even months, imaging the seabed in overlapping swathes, in the difficult, autumnal conditions of this region.

A typical search, like the ones I have been involved in, would typically start with a low-frequency system (eg 30 kHz), to map large swathes (kilometres wide) with a lower resolution (close to 10 m). Any unusual return would be noted down and further investigated, using higher-frequency systems covering smaller ranges (hundreds of metres or less) but with higher accuracies, metric or submetric. The metallic or composite hull of an airliner would show strong acoustic returns, even in rough terrains, and assuming it has not exploded or sunk into gullies, it would be detectable with sonar. The sad truth is that the plane is most likely to have exploded at impact, or imploded as it sank several kilometres. Debris would therefore be scattered over a wide field, depending on the different currents on the way down and on the sizes of the debris. The debris field, especially with its larger or more reflective components, would still be identifiable. Human remains, even after a few weeks in water, should still be identifiable with very high-frequency sonars. All evidence is usually complemented with video and photographic imagery, taken with autonomous or remotely-guided underwater vehicles, covering every possible inch of ground, feeding into possible loss scenarios, and helping any recovery deemed necessary (in the case of the Air France 447 flight several years ago, this included bodies, critical pieces of equipment and the black box recorder, two years later).

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