Australian ship detects new signals as plane hunt narrows
A fast response craft manned by members of ADV Ocean Shield's crew and Navy personnel pass by the starboard side of the ship as the boat searches the ocean for Flight MH370 in the southern Indian Ocean on April 7, 2014 - by LSIS Bradley Darvill
Australian ship Ocean Shield detected two more signals Tuesday to match a pair of transmissions picked up over the weekend that have been analysed as consistent with flight data recorder emissions, the head of the search said.
"Ocean Shield has been able to reacquire the signals on two more occasions, late yesterday afternoon and later last night," Angus Houston, head of the Joint Agency Coordination Centre, said.
The Australian ship has now picked up four transmissions, crucial information as searchers try to pinpoint the crash zone for the Boeing 777 that disappeared on March 8 with 239 people on board.
Officials had feared that the signals which were initially picked up may not be detected again, particularly as the batteries on the black box recorders have a life span of about 30 days.
The new transmissions, found in the same broad areas as the previous two, lasted for five minutes and 32 seconds and about seven minutes respectively, Houston said.
"Yesterday's signals will assist in better defining a reduced and much more manageable search area on the ocean floor," Houston said.
"I believe we are searching in the right area but we need to visually identify the aircraft before we can confirm with certainty that this is the final resting place of MH370."
Houston again urged caution for the sake of the families of the 239 people onboard the mysterious flight which went missing en route from Kuala Lumpur to Beijing and said the search for more transmissions would go on.
"Hopefully with lots of transmissions we'll have a tight, small area and hopefully in a matter of days we'll be able to find something on the bottom that might confirm that this is the last resting place of MH370," Houston told reporters.
- 'Not of natural origin' -
The hunt was now narrowing with experts confirming the first transmissions were consistent with black box data.
"The analysis determines that a very stable distinct and clear signal was detected at 33.331 kHz and that it consistently pulsed at a 1.106 second interval," Houston said.
"They therefore assessed that the transmission was not of natural origin and was likely sourced from specific electronic equipment.
"They believe the signals to be consistent with the specification and description of a flight data recorder."
Authorities have been searching a linear arc produced from satellite data believed to represent the last stretch of the plane's flight path, hoping to pick up the pings from the black box recorders.
Houston said the first "pings", picked up on Saturday afternoon and evening, were near the final radar "handshake" the plane made with satellites.
Up to 11 military aircraft, four civil aircraft and 14 ships were searching Wednesday over a zone covering 75,423 square kilometres (29,000 square miles), Australia's Joint Agency Coordination Centre said.
The focus of the search area is 2,260 kilometres (1,400 miles) northwest of Perth and JACC said scattered showers were forecast for Wednesday.
Officials say a submersible US-made sonar device called a Bluefin 21 will not be launched to comb the seabed until it was clear batteries that may be emitting pings from the black boxes had expired.
Houston said officials were probably close to using this device because the last acoustic signal was very weak, indicating the batteries were running down.
"I don't think that time is very far away," he said.
The case of the missing jet has baffled aviation experts and frustrated the families of those on board, two-thirds of whom were Chinese.
Despite extensive searches on the ocean surface, no debris from the flight has yet been found.