It would appear that, despite collecting data for several decades, we do not have baseline estimates for sea junk per area of ocean. Our watery world is crisscrossed by a conveyor belt of ships carrying container loads of materials, a portion of which fall into the water, joining the rubbish deliberately thrown overboard from ships and the rubbish which makes its way into the oceans from the stuff we throw into rivers and leave on beaches.
Baseline measures aren’t sexy. One unintended consequence of the search for flight MH370 is that we will have learnt that even the far reaches of the southern Indian Ocean, deep in the roaring forties, have generous scatterings of man made rubbish. Perhaps we will even be able to quantify this in terms of number of discriminable man made objects per thousand square miles.
Note that, if the number is very low (and the more appropriate measure turns out to be objects per ten thousand square miles, or even a hundred thousand square miles, which is a little over the size of the United Kingdom) this would strengthen the significance of finding any object floating in the ocean. Signal detection would become a little easier. We could argue, as the Malaysian government officials have done (they are not having a good time, are they?) that floating junk means floating plane junk. Find some junk and the plane will be on a sea bed somewhere upstream from the sea currents, if those can be calculated with any degree of precision.
On the other hand, if the number of floating objects is high, then the task becomes even more difficult, and pushes us towards the next problem: can crashed plane junk be discriminated by satellite or observer plane from all the other junk or do we have to rely on retrieval by ship of every likely floating object?
This question came into my mind a few minutes ago, when the revered BBC website displayed a picture taken by a journalist from a New Zealand plane showing a white floating rectangle. “I am no expert” as people say in the Twitter-sphere, (before launching into an elaborate speculation) but it is not immediately apparent to me how this object potentially relates to a crashed airliner. It is very probably nothing to do with the skin of the plane, nor does it look like any inner section, or any type of cargo. However, it is man-made, and floating.
So, how are our probability estimates looking at the moment? It seems that the range of the aircraft is fuzzier than previously disclosed. The plane was traveling faster than previously envisaged, thus burning more fuel, and therefore travelling less deeply into the southern wastes. If one plots out the error arc of the Inmarsat calculations, and the error range of the speed and fuel calculations, quite a chunk of ocean remains in contention. (I do not know how much, and wonder if anyone else does).
So, which way would you gamble, using Bayesian techniques? Three main components to be factored in are as follows: 1) area to be searched (ranging from the highly probable to the less probable) 2) the time left before the black box pinger battery gives up, and 3) search efficiency.
My rough calculations would be that: the search area remains too large; the pinger will fade to almost nothing in another 15 days (though cold water might extend that time) and search efficiency is extremely low. This latter point was well studied by the mathematician Bernard Osgood Koopman who wrote the first proper handbook for searches at sea in the 1940s. Looking at the sea is boring, you cannot scan the whole area so it is best to look a little down from the horizon, you should change places every 15 minutes to lift your alertness, you should start with probable places and move to slightly less probable place but ignore possible but improbable place (success is unlikely when probability of a target is low, and visual search is inefficient) and no plane can fly for ever.
My bet would be that, absent any more refinement in the calculation of impact location and subsequent drift, the searcher must gamble, and should maximise the area that can be searched. The area closer to Perth maximise the proportion of the target area that can be searched. Look where the light is brightest, particularly when the light is about to go out.
And finally, a word about reincarnation. About forty years ago I read somewhere, possibly in the Pali cannon of sayings of the Buddha or a commentary a line about the chance of someone being born without having been reincarnated. The chance was rated as being “as low the chance that a turtle that rises to the surface once in a thousand years will put its head through a life belt cast upon the Indian ocean”.
Can someone look it up for me? I am busy searching for a missing plane.