PM confident signals are from plane
Authorities are confident that a series of underwater signals detected in a remote patch of the Indian Ocean are coming from the missing Malaysia Airlines plane, Australia's prime minister has said.
"It's been very much narrowed down because we've now had a series of detections, some for quite a long period of time," Mr Abbott said.
"Nevertheless, we're getting to the stage where the signal from what we are very confident is the black box is starting to fade. We are hoping to get as much information as we can before the signal finally expires."
The Boeing 777's black boxes, or flight data and cockpit voice recorders, could help solve the mystery of why Flight 370 veered so far off course when it vanished on March 8 on a trip from Kuala Lumpur, Malaysia, to Beijing, China.
But the batteries powering their locator beacons last only about a month - and it has been more than a month since the plane disappeared.
The Australian ship Ocean Shield, which is towing a US Navy device to detect signals emanating from the beacons on a plane's flight data and cockpit voice recorders, first picked up two underwater sounds on Saturday that were later determined to be consistent with the pings emitted from the flight recorders. The ship's equipment detected two more sounds in the same general area on Tuesday.
"We are confident that we know the position of the black box flight recorder to within some kilometres, but confidence in the approximate position of the black box is not the same as recovering wreckage from almost 4 ½ kilometres beneath the sea or finally determining all that happened on that flight," Mr Abbott said.
An Australian air force P-3 Orion, which has been dropping sonar buoys into the water near where four sounds were heard earlier, picked up another "possible signal" yesterday, but Angus Houston, who is co-ordinating the search for Flight 370 off Australia's west coast, said an initial assessment of the signal had determined it was not related to an aircraft black box.
He said the Ocean Shield was continuing to use its towed pinger locator to try and locate additional signals today. The underwater search zone is currently a 500-square-mile patch of the ocean floor, about the size of the city of Los Angeles.
"It is vital to glean as much information as possible while the batteries on the underwater locator beacons may still be active," the retired air chief marshal said. "The AP-3C Orions continue their acoustic search, working in conjunction with Ocean Shield, with three more missions planned for today."
The Bluefin 21 submersible takes six times longer to cover the same area as the ping locator being towed by the Ocean Shield and would take six weeks to two months to canvass the current underwater search zone.
"On the information I have available to me, there has been no major breakthrough in the search for MH370,"Mr Houston added. "I will provide a further update if, and when, further information becomes available."
The searchers are trying to pinpoint the location of the source of the signals so they can send down a robotic submersible to look for wreckage and the flight recorders from the Malaysian jet. Mr Houston said that decision could be "some days away".
The area to be searched for floating debris has been narrowed to 18,036 square miles of ocean extending from 1,400 miles north west of Perth. Up to 15 planes and 13 ships are joining today's search.
Yesterday's search of a 22,300 square mile area of ocean in a similar location reported no sightings of potential wreckage.
The sonar buoys are being dropped by the Australian air force to maximise the sound-detectors operating in the search zone. Royal Australian Navy commodore Peter Leavy said each buoy is dangling a hydrophone listening device about 1,000 feet below the surface and transmits its data via radio back to a search plane.
Mr Houston has expressed optimism about the sounds detected earlier in the week, saying on Wednesday that he was hopeful crews would find the aircraft - or what is left of it - in the "not-too-distant future".
Meanwhile a Malaysian government official said investigators have concluded that it was the pilot who spoke the last words to air traffic control, "Good night, Malaysian three-seven-zero", and that his voice had no signs of duress.
A re-examination of the last communication from the cockpit was initiated after authorities last week reversed their initial statement that the co-pilot was speaking different words.