So after all that - tens of millions of dollars spent, 23 aircraft and 17 ships from eight nations searching the surface and an underwater drone painstakingly searching 850 square kilometres of ocean floor - it turns out the pings once thought to be coming from the black boxes were probably something else. MH370 is almost certainly somewhere in the Indian Ocean, but we have less of an idea today than we thought we did a week ago.
OPINION: Now, the quest to find the Malaysia Airlines Boeing 777-200, then figure out why it vanished 86 days ago with 239 people on board, is about to enter a new, dauntingly difficult, phase. The search area has ballooned back out to an estimated 56,000 square kilometres, an area defined by information that we knew months ago: the timing of the final automatic "handshake" communications between the doomed flight and an Immarsat satellite.
While no one is seriously suggesting it was a mistake to swiftly deploy searchers on the basis of "pings" that have turned out be misleading, it looks like it is time to go back to basics, and bring in a new set of professionals - the commercial operators with some hard-won expertise in finding things underwater.
One of those is Kiwi Rob McCallum. In today's Sunday Star-Times he says the recent search for the black boxes "was worth every effort", but now that it has turned out to be fruitless, it's time to stop, regroup and do the "fully Monty" version.
McCallum says it should be possible to narrow the focus of the search to around 30,000 square km. That is still a mindbogglingly vast area - about a ninth of the land area of New Zealand - but he says he's confident he can find the plane: "That's what we do for a living."
Of course he would say that - he is partner in a Seattle-based company that is among those tendering for an underwater search contract. But he also has the experience and standing to make bold claims.
McCallum was project leader of the underwater search team that in April 2011 finally found the black box of Air France 447, an Airbus A330-200 that had crashed into the Atlantic off the coast of Brazil almost two years earlier with 228 on board. A crucial aspect of that search - which came on the heels of numerous failed attempts - was a sophisticated mathematical re-evaluation of the probable location of the wreckage by an American- based consultancy, which provided guidance to McCallum's team.
McCallum has also been at the heart of other high-profile underwater adventures, including leading manned submersible expeditions to the Titanic and the Bismarck, and was involved in the planning stages of James Cameron's historic solo dive into the Marianas Trench.
The latest phase of the MH370 search will be staggeringly expensive - and could take a long time. The Australian government alone has already spent around $30m, and budgeted up to $100m. The commercial operation being tendered won't even start till around August, to allow time for completion of a Chinese-led "bathymetric" survey of the search area to be followed by a more detailed underwater search.
Seven weeks ago, Australian PM Tony Abbott said he was "confident that we know the position of the black box flight recorder to within some kilometres". Clearly, that confidence was misplaced. For the relatives of those on board, who have been buffeted by false leads, wild accusations and absurd conspiracy theories, this latest reversal in the hunt for MH370 must be agonising: some have taken the news as fresh cause to cling to the hope that their loved ones are still alive, somewhere, somehow.
That hope is a forlorn one. Yet as the search for MH370 settles in for what is likely to be a long, hard haul, the example of that Air France flight provides a different kind of hope: not that some miracle will bring anyone back alive, but that intelligent analysis, dogged persistence and hard work will, eventually, crack this mystery.
- Sunday Star Times
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