THE Prime Minister has given the most detailed information about where the crucial black box flight recorders from missing Malaysia Airlines flight MH370 are expected to be.

Tony Abbott gave Chinese President Xi Jinping a private and detailed briefing in Beijing about the latest on the search for the missing Boeing 777-200ER aircraft which had 154 Chinese people on board.

The MP told the President before a State dinner with the Australian premiers at the Great Hall of the People in Beijing — an unprecedented audience — that search teams led by the Australian ship Ocean Shield had narrowed down the area in the Indian Ocean where pings from the flight recorders are being received to a grid of around 10km by 10km.

He told President Xi that there is now a high degree of confidence that the signals were the black boxes.

ANGUS HOUSTON: Man charged with finding flight MH370 rejected by RAF

FLIGHT MH370: What lies beneath the southern Indian Ocean

News_Image_File: Search continues . Leading Seaman Aircrewman (LSA) Daniel Colbert winches LSA Joel Young into the water from HMAS Toowoomba's S-70B-2 Seahawk helicopter Tiger 75 to retrieve possible debris.

The PM then personally invited President Xi to address the Australian parliament later this year. President Xi will be only the second Chinese leader to be invited to address Parliament since Hu Jintao visited in 2007.

The Australian vessel Ocean Shield towing a US Navy device that detects black box signals has to date recorded four signals that are believed to have come from at least a black box flight recorder. The ocean Shield was today in an area about 2200km northwest of Perth continuing sweeps of its pinger locator to detect further signals. Orion aircraft were also continuing acoustic searches.

The plane’s black boxes, or flight data and cockpit voice recorders, may hold the answers to why the aeroplane lost communications and veered so far off course when it vanished on Saturday March 8 while flying from Kuala Lumpur, Malaysia, to Beijing with 239 people on board.

Search crews are racing against time because the batteries powering the devices’ locator beacons last only about a month — and more than a month has passed since the plane disappeared. Finding the black boxes after the batteries fail will be extremely difficult because the water in the area is 4,500 meters deep.

The PM had described the loss of Malaysian flight MH370 as one of the “great mysteries of our time”.

“It is probably the most difficult search in human history,” Mr Abbott said in a speech to 1800 people at the official launch of Australia in China week.

“I thank the government and people of China for the help that they have given to Australia as we lead this search and recovery effort.

“We are confident that we know the position of the black box flight recorder to within about a kilometre.

“Still, confidence in the approximate position of the black box is not the same as recovering wreckage from almost four and half kilometres beneath the sea or finally determining all that happened on that flight.”

News_Image_File: Working together ... Commanding Officer of HMAS Success Capt. Allison Norris, RAN, greets the Peoples Liberation Army Navy Liaison Officer Commander Lin Wan from the Luyang II class guided missile destroyer Haikou (DDG-171). Picture: Julianne Cropley/Australian Department of Defence

Delivering a personal message of condolence for the families and friend of 154 Chinese victims, Mr Abbott assured the Chinese leadership “that Australia will not rest until we have done everything we can to provide comfort and closure. You will be among sorrowing friends should you choose to come to Australia.”

However there was some confusion as — almost at the same time as Mr Abbott was speaking — the head of the agency leading the search issued a statement saying there were no new breakthroughs.

Air Chief Marshal Angus Houston, head of the Joint Agency Coordination Centre said a decision to send a robotic submersible could be “some days away.”

The Bluefin 21 submersible takes six times longer to cover the same area as the pinger locator being towed by the Ocean Shield and would take six weeks to two months to canvass the current underwater search zone.

News_Module: NND MH370 Black Box Breakthrough Multipromo

The signals are emanating from 4,500 metres below the surface, which is the deepest the Bluefin can dive. The search coordination centre said it was considering options in case a deeper-diving sub is needed.

Investigators believe the plane went down in the southern Indian Ocean based on a flight path calculated from its contacts with a satellite and analysis of its speed and fuel capacity.

Today’s optimism that the black box had been located arose from a more recent spotting by a ship.

The report was Tweeted by aviation expert Geoffrey Thomas, the editor-in-chief of the website airlineratings.com and executive editor of AirlineReview.com.

Mr Thomas told Perth radio station 6PR that the Ocean Shield and the HMS Echo have both left the search area “at speed” and sources had told him there was a possibility they had “triangulated” and located the black box.

“Echo has come along and done a radar scan, an echo scan if you like, along the bottom and they’ve had a return which is a positive, which may indicate the wreckage of a plane.”

News_Rich_Media: Tony Abbott says he is very confident the signals are from MH370 but are weakening. Courtesy: Sky

He stressed these were unconfirmed reports but “if they are firm enough to say we have located the black box, that is enough for them to launch the Bluefin 21 to go down to the bottom and take photographs or scan the bottom with a sonar scanner.

“It will either take an electronic scan or it will have a camera and lights and take a photograph.

“If HMS Echo has come in and done a scan of the ocean floor over their triangulated best estimate, then all of the sudden you’re getting a very positive return off the ocean floor.

“Don’t forget, the ocean floor is all silt, a big object like a 250 tonne aeroplane, it is going to give you a different shaper return, rather than a softer return.”

Asked about the search effort, Mr Thomas said: “I think they have done an absolutely outstanding job, I mean the international collaboration now basically led by the Australians, with the United States, the British, the Malaysians and the Chinese. I think they’ve done an extraordinary job given the limited information they had to start off with ... to have found this so quickly is outstanding.”

News_Module: NND MH370 Clues In The Deep Multipromo

FROM EARLIER TODAY

Search crews have detected a new signal thought to be from missing Malaysia Airlines Flight MH370 from the depths of the Indian Ocean.

Former Defence chief Angus Houston, heading the Joint Agency Coordination Centre in Perth, confirmed an aircraft has detected a fifth signal in the vicinity of Australian defence vessel Ocean Shield, during the search for the missing Malaysia Airlines plane.

The signal was detected by a RAAF P-3 Orion plane in the search zone, and is potentially from a man-made source.

The command centre handling the hunt for the missing Malaysia Airlines plane is analysing a freshly detected underwater sound that could have come from a man-made source, possibly the jet’s black box.

News_Image_File: The sun sets ... as Able Seaman Communications and Information Systems Noel O'Brien keeps a look out from the port flag bin of HMAS Toowoomba, as Operation southern Indian Ocean continues. Picture: LSIS James Whittle/Australia Department of Defence

Retired air chief marshal Angus Houston, who co-ordinates the joint agency search from Perth, says the hunt has yielded a potential new lead after an RAAF Orion aircraft detected a signal in the vicinity of the vessel Ocean Shield.

“The acoustic data will require further analysis overnight, but shows potential of being from a man-made source,” the former defence force chief said in a statement on Thursday evening.

The RAAF has been dropping buoys carrying microphones from planes near where the earlier sounds were heard.

Royal Australian Navy Commodore Peter Leavy said each buoy was dangling a hydrophone listening device about 300 metres below the surface.

News_Image_File: Fifth signal ... Angus Houston said the new signal will require further analysis to confirm it is from a man-made source. Picture: AP

DETAILS OF FRIDAY’S SEARCH

Up to 15 aircraft and 13 ships will be part of today’s search effort in two areas close to each other, more than 2300 kilometres north west of Perth.

Isolated showers are predicted, with 10 — 15 knot southerly winds and sea swells of up to 1.5 metres.

No objects were sighted or recovered yesterday.

Ocean Shield failed to detect underwater signals yesterday after positive transmissions thought to be from Malaysia Airlines Flight MH370 were received on Saturday and Tuesday.

“They continued the pinger operations through the night,” Mr Houston said.

“They haven’t picked up anything. I don’t know how much longer they’ll go for because the likelihood on Day 34 is that the batteries must be getting near their use-by date.”

Meanwhile, British Royal Navy survey ship HMS Echo is arriving in the area help the Ocean Shield.

News_Image_File: Grief ... A woman ties a message card for passengers on-board the missing Malaysia Airlines Flight 370 at a shopping mall near Kuala Lumpur. Picture: AP

The hydrographic survey ship, whose specialist equipment can scan the seabed and has been specially adapted to listen for the sonar pings, was diverted from her patrol in the Indian Ocean after a request from the Malaysian authorities for support.

Searchers have not yet decided to send down the US Navy’s Bluefin 21, an autonomous underwater vehicle that is able to travel deep underwater.

The two transmissions that were received on Tuesday were markedly weaker than the two sustained transmissions heard on Saturday.

Both sets of transmissions have been determined to be consistent with man-made frequencies coming from aeroplane black boxes.

Malaysia’s acting Transport Minister Hishammuddin Hussein said he remains “cautiously optimistic” after the latest ping.

News_Image_File: New pings ... Sub Lieutenant Ryan Penrose watches HMAS Success as HMAS Perth approaches for a replenishment at sea while searching for missing Malaysia Airlines flight MH370. Picture: AFP/AUSTRALIAN DEFENCE/ABIS NICOLAS GONZALEZ

Mr Houston has said he believes MH370 will be found “in the not-too-distant future”

“Hopefully in a matter of days, we will be able to find something on the bottom that might confirm that this is the last resting place of MH370,” he said.

Mr Hussein told the BBC he was confident search teams were getting closer to discovering the wreckage.

“I know there will be answers. I know we will find the plane. It is just a matter of when,” he said.

Originally published as MH370 black box within 10km grid