An Australian navy vessel is heading out from Perth with special equipment able to detect signals from the black box recorder on missing Malaysia Airlines flight 370.
The Ocean Shield was due within the Indian Ocean search zone early on Monday to join an international array of ships and aircraft scouring the seas for any sign of the lost plane.
It's dispatch comes with one of Australia's P-3 Orions spotting four orange-coloured objects at sea, each more than two metres in size.
The co-ordinates and images of the items, the latest to be sighted, were "of interest" but would need to be analysed, Flight Lieutenant Russell Adams told Fairfax Media from RAAF Pearce base after returning from an 11-hour mission on Sunday night.
Authorities say that objects scooped out of the ocean off Western Australia are not part of missing Malaysia Airlines Flight 370.
The Australian Maritime Safety Authority has confirmed a Chinese ship retrieved objects from the southern Indian Ocean on Saturday.
However, it's believed the items are not related to the flight and are more likely fishing objects or rubbish, AMSA said on Sunday.
US Navy Officer Captain Mark Matthews, who will today lead the search for MH370 debris, says finding the missing passenger jet in the current circumstances is "untenable".
"It all depends on how effective we are at reducing the search area," said Captain Matthews.
"Right now, the search area is basically the size of the Indian Ocean, which is an untenable amount of time to search."
A GPS buoy had also been dropped in the area of the sighting, Lt Adams said.
Similarly, the specialist US Navy technology on board the Ocean Shield will not be able to detect the "pinger" within the plane's black box until a more confined search area is identified.
Meanwhile former Defence force chief Angus Houston has been named to co-ordinate the international search effort for the plane carrying 239 passengers and crew, which disappeared more than three weeks ago.
Retired Air Chief Marshal Houston will lead a new joint agency co-ordination centre in Perth, News Corp reports.
On Saturday, Chinese aircraft spotted three new objects floating in an area off the West Australian coast where search teams are focusing their hunt for the missing Malaysia Airlines plane.
The development came as an Australian Navy frigate was dispatched to join the operation, which is now focused on a new search zone more than 1000km from where teams had previously been scouring the Indian Ocean.
China's state news agency Xinhua reported on Saturday that the Chinese military plane, Ilyushin IL-76, had spotted three floating objects of white, red and orange colours respectively, from an altitude of 300 metres.
Satellites and aircraft have spotted numerous floating objects, but none have been confirmed as wreckage from the plane.
Planes and ships on Saturday combed the newly targeted area with Prime Minister Tony Abbott saying authorities were transporting a black box locator to the search zone.
Flight 370 disappeared on March 8 after veering sharply off course while heading from Kuala Lumpur to Beijing with 239 passengers, including six Australians, and crew.
Investigators believed the Boeing 777 crashed in the southern Indian Ocean off the coast of Western Australia, where planes and ships have been looking for more than two weeks in the hope of recovering debris.
HMAS Toowoomba was due to leave a Perth naval base on Saturday afternoon and help with the search after being diverted from other operational tasks.
It will take with it a S-70B2 Seahawk helicopter.
Another Australian navy ship, the Ocean Shield, was due to leave Perth on Sunday to join the search.
The plane and its passengers have been missing for three weeks, but Malaysia's transport minister has vowed to continue the search for "possible survivors."
"No matter how remote the odds, we will pray, hope against hope, and continue to search for possible survivors," Hishammuddin Hussein told reporters on Saturday during a condolence visit to relatives of Malaysian passengers and crew.
Malaysia says the plane was deliberately diverted from its planned flight path, and investigations have focused on the captain.
Malaysian police, the US Central Intelligence Agency and Federal Bureau of Investigation, Chinese intelligence and Britain's MI6 are involved in the investigation.
The search zone shifted 1100 kilometres on Friday following a fresh assessment of satellite data.
It's about 80 per cent smaller than the previous search zone but still spans 319,000 square kilometres.
The Australian Maritime Safety Authority (AMSA) said ships were trying to recover objects first spotted on Friday, including two rectangular items that were blue and gray.
"The objects cannot be verified or discounted as being from MH370 until they are relocated and recovered by ships," AMSA said in a statement.
"It is not known how much flotsam, such as from fishing activities, is ordinarily there. At least one distinctive fishing object has been identified."
Weather was against the searchers on Saturday with a cold front bringing rain, low clouds and reduced visibility to the southern part of the search area, while moderate winds and swells of up to two meters were predicted by the Bureau of Meteorology.
Conditions are expected to improve by Sunday but rain, drizzle and low clouds are still likely.
Race to find the black box
Searchers racing to find flight MH370's "black box" face daunting hurdles ranging from undersea volcanoes to mountainous seas as they operate in one of Earth's most remote locations, experts have said.
They warned there was no guarantee that an unprecedented international search operation involving the militaries of six nations would succeed in retrieving the recorder from the doomed Malaysian Airlines plane which disappeared on March 8 with 239 people on board.
Australian Prime Minister Tony Abbott on Wednesday said the search zone -- in the southern Indian Ocean some 2,500 kilometres southwest of Perth -- was "as close to nowhere as it's possible to be".
University of New South Wales oceanographer Erik van Sebille said the crash site was in an area known as "the Roaring Forties", notorious among mariners for its hostile seas.
"In general, this is the windiest and waviest part of the ocean," he said. "In winter, if a storm passes by you can expect waves of 10-15 metres."
The Soufan Group, a US-based strategic security intelligence consultancy, likened searching for debris in such conditions to "finding a drifting needle in a chaotic, colour-changing, perception-shifting, motion-sickness-inducing haystack".
"A random wave might obscure the object when the eyes pass over it; sun glare off the water may blind momentarily; a look two degrees to the left when the object is most visible may cause the moment to pass," it said.
Even with verified wreckage from MH370 on the surface, geologist Robin Beaman said underwater volcanoes would probably hamper efforts to recover the black box flight recorder from the depths.
- Pilot 'not in state of mind to fly' -
A friend of the pilot of missing Malaysia Airlines flight MH370 said he was going through marriage problems at the time the plane went missing.
Captain Zaharie Ahmad Shah was reportedly going through a separation with his wife, and problems with another woman he was seeing at the time, in the days leading up to the disappearance.
The friend told the New Zealand Herald that Captain Zaharie was "terribly upset" and may have been taking the flight to a place he'd never been before.
"He's one of the finest pilots around and I'm no medical expert, but with all that was happening in his life Zaharie was probably in no state of mind to be flying," the friend said.
Captain Zaharie was known to be a big fan of flying, and investigators were still examining a home-made flight simulator set up in his house.
Several files were reportedly deleted from the simulator a month before the plane disappeared on March 8.
The friend told the New Zealand Herald he had spoken several times with Captain Zaharie, and that they had talked about him simulating situations such as flying at very high or very low altitudes.
"It is very possible that neither the passengers nor the other crew on-board knew what was happening until it was too late," the man said.
The new suspicion comes on the back of claims from an official that the incident was a deliberate attempt at suicide.
"This has been a deliberate act by someone on-board who had to have the detailed knowledge to do what was done," the newspaper's source said.
- 'I know my father better' -
But Ahmad Seth, the youngest son of Zaharie Ahmad Shah, has defended his father saying that the veteran pilot would not be involved in the plane's disappearance.
“I’ve read everything online. But I’ve ignored all the speculation. I know my father better,” the the New Strait Times quoted him as saying.“We may not be as close as he travels so much. But I understand him,” he said.