Two more acoustic signals consistent with a black box flight data recorder have been picked up by an Australian navy ship in the search for the missing Malaysia Airlines plane.
Retired air chief marshal Angus Houston, who is in charge of co-ordinating the search from Perth, on Monday said it was probably the best information of the search so far.
It was revealed on Sunday that two “acoustic events” had been picked up by Chinese ship Haixun 01 using hydrophones while the Australian vessel, Ocean Shield, had detected another two signals in a different part of the Indian Ocean search zone.
Air chief marshal Houston said the Ocean Shield, which is towing a pinger detector, had since picked up signals consistent with black box emissions on two separate occasions in the northern part of the search zone, where the water depth is about 4500 metres.
The first detection was held for about two hours and 20 minutes before contact was lost.
The second detection, made as the vessel back-tracked, was held for about 13 minutes.
“On this occasion, two distinct pinger returns were audible,” air chief marshal Houston told reporters on Monday.
“Significantly, this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder.
“Clearly, this is a most promising lead.
“In the search so far, it’s probably the best information that we’ve had.
“I’m much more optimistic than I was a week ago.”
But he warned against jumping to conclusions, saying more information was needed.
“We haven’t found the aircraft yet and we need further confirmation – I really stress that,” he said.
“There are many steps yet before these detections can be positively verified as being from missing flight MH370 … it could take some days before the information is available.
“In very deep oceanic water, nothing happens fast.”
The signals were detected just under 2000 metres apart but it was quite possible – because of the attenuation of audio under water – that the sounds came from the same source on the sea bed, Royal Australian Navy Commodore Peter Leavy said.
The priority is to reacquire the signal before Ocean Shield deploys an autonomous underwater vehicle that will attempt to find and photograph any wreckage on the sea floor.
Air chief marshal Houston said the vehicle’s capability was stretched to its limit at the water depth of the current search zone.
“We’re right on the edge,” he said.
US Navy Captain Mark Matthews said the vehicle’s imaging capability was just a few metres, “but sidescan sonar can extend another, maybe, 100 metres”.
Air chief marshall Houston said the black box beacon’s battery must be getting close to the end of its life.
“We’re already one day past the advertised shelf life,” he said.
“We hope that it keeps going for a little bit longer.”
White floating objects spotted at the weekend by the Chinese had been checked and had no relationship to the missing plane.
MH370 disappeared on a flight from Kuala Lumpur to Beijing on March 8.
All 239 passengers and crew are presumed dead.