Thursday, May 22, 2014
Barend Vlaardingerbroek from Lebanon: Flight MH370 – we’re not as clever as we thinkLabels: Barend Vlaardingerbroek, MH370, Technology
Just on two and a quarter centuries ago, Fletcher Christian and his fellow mutineers headed into the vast expanses of the mid-Pacific looking for a habitable island that did not appear on any maps. That way, they figured, the Royal Navy wouldn’t come looking for them there. They found such an island – it had earlier been mapped but the coordinates were miles out – and settled there with their Tahitian wives, the descendents now being the people of Pitcairn. It was not until almost two decades had elapsed that an American whaler stumbled upon the island, by which time there was but one surviving mutineer.
Times have changed. We would like to think that there is no way a ship can just sail off into oblivion nowadays, whether it stays afloat or sinks. We have all sorts of gizmos and gadgets these days, from satellites above to robotic submersibles below, that will enable us to locate it. HMAS Sydney took 67 years to find, which goes to show how far technology has progressed in that time.
Ships are big things – you can’t just make them vanish into thin air (or thick water). The same goes for aeroplanes. There have been aeroplane disappearances, but most were quite some time ago now and few, if any, real ‘mysteries’ remain – one that did qualify for this overused term was British South American Airways Lancastrian ‘Star Dust’ which vanished on a flight in 1947; melting ice half a century later revealed that it had smacked into the Argentine Andes. But for something as big as a Boeing 777 packed full of people to just ‘vanish’ in this modern electronic age is in the realm of morbid fantasy, isn’t it?
Along comes Flight MH370 and we may have to reconsider our answer to that last question very carefully. Are we really as clever as we like to think?
There was, of course, Air France Flight 447 which ended up at the bottom of the North Atlantic in 2009. It had ‘vanished’ in a sense, but we knew almost precisely where it went down and set out to find it and ascertain what had gone wrong. Sure enough, it was found and the ‘black boxes’ were recovered, the cockpit voice recorder revealing the cause of the disaster as having been an instance of protracted stupidity on the part of the cockpit crew so crass that a kid with a Microsoft flight simulator on his desktop at home would blush crimson with shame should s/he do the same. But at least we now knew what had happened.
The MH370 mystery appears to be far removed from the domain of incompetence and stupidity. On the contrary, it is tempting to think that the events of the first hour of flight MH370 constitute a masterly deception aimed at evoking memories of Flight 447. The disabling of the ACARS (Aircraft Communications, Addressing and Reporting System) and then the transponders a little later made the plane ‘invisible’ to ground stations (which, unlike military radar, rely on signals sent from the aircraft). The ‘chat’ between the cockpit and ground control stopped just as the plane was about to enter Vietnamese airspace, after which contact was lost, adding to the illusion that the plane literally fell out of the sky as it was about to leave Malaysian airspace. If a planned deception it was, it certainly worked: within a couple of days, the navies of several countries were out looking for traces of the presumed downed aircraft in the South China Sea.
However, the plane had not fallen completely silent. There was still the ‘pinger’ system sending out periodic signals that were picked up by Inmarsat. But you can’t get a locational fix on a plane from those ‘pings’. So someone came up with the idea of applying the Doppler Effect to the received ‘pings’ and working out from those the speed at which the aircraft had receded from the satellite after clearing the Malay peninsula for the second time (it having reportedly been ‘seen’ by military radar as it did so). This gave rise to two routes the plane could have taken, one north towards Tajikistan and one south into the recesses of the southern Indian Ocean; Inmarsat being above the equator and not being able to tell from which direction the signals had come, either was possible.
For those whose high school physics is a bit rusty, a quick explanation: the Doppler Effect is the compression of waves emitted by a moving wave-emitting source in front of it and the rarefaction of the waves in its wake. When applied to sound, it explains why the wailing of the siren on a fast-moving ambulance or police car is at a higher pitch as it is approaching us than when it has passed us and is moving away. The Doppler Effect was famously applied to electromagnetic radiation by Edwin Hubble, who inferred the ‘Red Shift’ from the radiation emitted by distant galaxies and thereby worked out that the universe is expanding. It seems to present a viable way of tracking a moving object, but there is a snag: if the speed of the moving object is very, very slow compared to the speed of the wave, the effect becomes negligible for practical intents and purposes. Take a kid riding a tricycle at a speed of 1 metre/second; the speed of sound in air is about 340 metres/second, so that’s 0.3% of the speed of the wave being emitted. In practice, you wouldn’t have a hope of tracking the kid’s trajectory at all accurately from the sound of the wheels on the riding surface as received by a microphone. The speed of electromagnetic radiation is about 300,000,000 metres/second and while a jet airliner belts along at about 250 metres/second, that’s a mere 0.00008% of the speed of the emitted wave. Sure, if sound waves and radio waves travelled at a perfectly constant speed and without any distortion through the air and your equipment gave you accuracies of measurement well within those limits, the task would be feasible; but neither of these conditions hold in the real world.
To cut a long story short, it was no real surprise when the search teams looking for MH370 pretty well gave up on the plotted route over the Indian Ocean. It had been a very long shot indeed, and had not paid off. (Yes, there was the ‘ping’ from what was thought to be a ‘black box’ at one stage, but it was also reported that the Chinese search vessel had on at least one occasion picked up its own signal........)
As readers will be aware, there is no dearth of theories as to what happened to Flight MH370. As always, the conspiracy theorists have been working overtime. A newly-released book (some people are very fast on a keyboard!) claims that the plane was shot down. Mahathir Mohamad is now in on the act claiming a CIA cover-up. I will recall the advice of Sherlock Holmes in A Scandal in Bohemia: "It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts." If we are to be really honest with ourselves, we have precious little idea what happened after that first hour.
We do like to think that we are just so clever with all that we know about the way the physical world works and all the sophisticated gadgetry that we have at our fingertips, but large objects full of people can still ‘disappear’ as they could back in the days of the mutiny on the Bounty – in the case of Flight MH370, right under our very noses. A large dollop of humble pie, to be eaten in a contemplative mood, would appear to be in order.
Dr Barend Vlaardingerbroek is an associate professor of education at the American University of Beirut. Feedback welcome at firstname.lastname@example.org.
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