Evidence that Malaysia Airlines Flight MH370 ended up in the vast, desolate waters of the southern Indian Ocean appears to be mounting - but the quest to find the doomed aircraft itself is still proving tortuously difficult.
French satellite pictures handed to Malaysian authorities late yesterday show possible debris from the missing Boeing 777, photographed in broadly the same area as objects picked up by Australian and Chinese satellites last week.
Read more from the Herald's Anna Leask and Greg Ansley in Australia:
• Flight MH370: Plane's captain 'got mystery call'
• Rival nations join forces as 'awesome' technology scours ocean
A plane scouring the search area, about 2,500km south-west of Perth, spotted a wooden pallet and other objects late on Saturday, including what looked like variously coloured straps or belts.
However, it was unable to get up close or take photographs, and other aircraft dispatched to the site on Sunday could only see seaweed.
Australian Prime Minister, Tony Abbott, expressed cautious optimism about a possible breakthrough in the 16-day hunt for the plane, which vanished off civilian radar screens with 239 passengers and crew during a night flight from Kuala Lumpur to Beijing.
It is the third detection by satellites of possible wreckage from the missing Malaysia Airlines Boeing 777-200ER.
The Australian Maritime Safety Authority, which is leading the search in waters off Australia, declined to offer details about the information from France. The authority did not respond to multiple requests by The Associated Press for access to the data.
"Any satellite images or other new information that comes to AMSA is being considered in developing the search plans,'' AMSA said.
But a Malaysian official involved in the search mission said the French data consisted of radar echoes captured on Friday and converted into fuzzy images that located objects about 930 kilometres north of the spots where the objects in the images released by Australia and China were located.
One of the objects located was estimated to be about the same size as an object captured on Tuesday by the Chinese satellite that appeared to be 22 metres by 13 metres, said the official, who declined to be identified because he isn't authorised to speak to the media. It was not possible to determine precise dimensions from the French data, the official said.
Trying to "re-find" wooden pallet
Information about the new data emerged as authorities coordinating the search, which is being conducted about 2,500 kilometres southwest of Perth, sent planes and a ship to try to "re-find'' a wooden pallet that appeared to be surrounded by straps of varying lengths and colours. It was spotted on Saturday by spotters in a search plane, but no images were captured of it and a military PC Orion military plane dispatched to locate the pallet could not find it.
"So, we've gone back to that area again today to try and re-find it,'' said Mike Barton, chief of the Australian Maritime Safety Authority's rescue coordination center. An Australian navy ship was also involved in the search.
Wooden pallets are commonly used in shipping, but can also be used in cargo containers carried on planes.
AMSA said the aircraft that spotted the pallet was unable to take photos of it.
"We went to some of the expert airlines and the use of wooden pallets is quite common in the industry,'' Barton said.
"They're usually packed into another container, which is loaded in the belly of the aircraft. ... It's a possible lead, but we will need to be very certain that this is a pallet because pallets are used in the shipping industry as well.''
Search conditions deteriorate
A relative of passengers aboard the missing Malaysia Airlines flight expresses her frustration at the lack of information. Photo / AP
Air Component Commander at Air Force Headquarters Mike Yardley says the New Zealand crew encountered poor conditions - and there's a cold front coming in today.
"The conditions were not great, actually deteriorated significantly from our previous flight. There was sea fog in half the area, and a cloud base of 600 foot in the other half of the area.''
Air Commodore Yardley told Newstalk ZB's Mike Hosking the P3 Orion's sensors are very good, and the radar is especially good.
Last night they were picking up marine life on the radar.
The Kiwi crew has a rest day today but 10 other planes are going out to the search area, including for the first time Japanese and Chinese aircraft.
'Two-minute opportunity' to seize plane
Meanwhile authorities investigating the jet's disappearance have narrowed down their investigation to the aircraft's two pilots following extensive analysis of data from the plane.
Senior sources involved in the investigation told the Sunday Telegraph that they remained certain the disappearance of the Boeing 777 was a result of a "deliberate act" by a "person or persons on board".
Two weeks after the plane vanished, investigators have largely ruled out the possibility the Malaysia Airlines flight might have suffered a fire that knocked out all communication systems and killed the pilots. The plane would then have had to fly on autopilot until it ran out of fuel and before any mayday message could be sent.
But they are doubtful whether a passenger could have seized control of the aircraft, after a study of transcripts between air traffic control and the co-pilot suggested a would-be hijacker would have had only a two-minute window of opportunity.
That leaves inquiries increasingly focused on Captain Zaharie Ahmad Shah, 53, and his co-pilot Fariq Abdul Hamid, 27.
A source close to the investigation said: "We're still on the notion of a deliberate act, but who it was is unknown and for what reason is unknown. The finger of suspicion is pointing towards the pilots.
"The pilots were only seriously investigated after the view emerged that someone on board did something deliberate rather than it being an accident."
The source said "the most plausible" explanation after two weeks' inquiries is that the pilots, either in concert or alone, proceeded to lock themselves into the cockpit and hijack the flight.
Royal Australian Air Force pilot Capt. Russell Adams, left, speaks to the media after returning from a search mission. Photo / AP
Foreign intelligence agencies last week completed a second round of vetting of each of the passengers, including two Iranians travelling on false passports, and cleared them all. Only a Russian passenger - who is not believed to be suspect - apparently remained to be fully vetted, because authorities in Moscow have been preoccupied with the crisis in Crimea.
Crunching the numbers
The transcript of exchanges between the pilots and air traffic control, which has been obtained by the Telegraph, has been the focus of the investigation - in particular between 1.07am and 1.21am, when the first signs emerged something was amiss aboard MH370.
At 1.07am, 26 minutes after take-off, the plane's Acars automatic signalling device sent its last message before being disabled at some point in the next half an hour. The device was timed to send a signal every 30 minutes.
Then at 1.19am, Hamid, the co-pilot, spoke his last known message of "All right, good night" to air traffic control in Malaysia as the plane shifted into Vietnamese airspace. Investigators are still completing analysis of Hamid's voice pattern to determine whether the 27-year-old, who was planning to marry his 26-year-old pilot girlfriend, was being coerced or was speaking under duress.
Two minutes after the final message at 1.21am, the plane's transponder was turned off, apparently deliberately disabled. MH370 slipped off Malaysian radar screens nine minutes later.
If passengers had seized control of the plane, they would likely have done so in the two-minute window between the point when Hamid spoke to air traffic control and the moment the transponder was switched off.
Aside from a glimpse on Malaysian military radars, which showed the plane had steered wildly off course, MH370 has not been seen since. As yet, however, police have found no evidence of a plot cooked up by the pilots or of signs that either man had psychological problems.
Malaysian police are hoping vital clues may emerge from Captain Zaharie's three-screen home flight simulator, on which he played three games: Flight Simulator X, Flight Simulator 9 and X-Plane 10.
The bizarre westward turn by MH370 while above the Gulf of Thailand took the plane on to routes that Malaysia Airlines does not fly; if the plane, as is believed, ended up in the southern Indian Ocean, neither pilot had previously steered a plane there.
On February 3, apparently some weeks before he would have been aware of the flight details for MH370, Zaharie deleted the game logs from his simulator. It is believed he practised on five runways across the Indian Ocean.
FBI forensic experts are trying to recover the files but early assessments have found nothing suspicious. A complete copy of the machine's hard drive has been sent to the US for further investigation.
- Additional reporting AP