The approximate location of missing Malaysia Airlines Flight MH370 deep in the Indian Ocean could be known within days as ships focus on a fading series of pings "likely sourced from specific electronic equipment".
Although the Australian-led search team remains more cautious, Prime Minister Tony Abbott told reporters in China yesterday that he was confident the signals were from the aircraft's black box flight recorder.
"We are confident that we know the position of the black box to within some kilometres, but confidence in the approximate position of the black box is not the same as recovering wreckage from almost 4.5km beneath the sea," he said.
The search, involving an international task force of 13 ships and 15 military and civil aircraft, is an increasingly desperate race against time as the strength of the signals detected by sophisticated electronic listening devices weaken.
The 30-day lifespan of the black box battery has expired.
"It is vital to glean as much information as possible while the batteries on the underwater locator beacons may still be active," the head of the search's Joint Agency Co-ordination Centre, retired Air Chief Marshal Angus Houston, said yesterday. When searchers believe they are close to the black box, which contains data and cockpit recordings, they will lower the American autonomous underwater vehicle Bluefin-21 to comb the ocean floor.
Finding the wreckage will take even longer. The AUV will move at a snail's pace across valleys and ridges up to 4.5km beneath the ocean surface.
Abbott's comments in China raised speculation that searchers were about to announce a significant discovery. More than 150 Chinese nationals were among the 227 passengers and 12 crew aboard MH370 when it vanished on March 8.
But it appears he was giving a more upbeat assessment of information previously released by Houston, who said after Abbott's comments that there had been "no major breakthrough in the search for MH370".
This week the Ocean Shield picked up four signals in an area less than 40km apart, similar to those emitted by an aircraft's black box.
Houston said analysis by the Australian Joint Acoustic Analysis Centre of one reading had determined that the signal "was not of natural origin and was likely sourced from specific electronic equipment ... consistent with a flight data recorder".
Analysts had earlier dismissed a fifth possible signal detected by an Australian P-3 Orion as unrelated to an underwater aircraft beacon.