Despite an extensive multinational search southwest of Perth, no wreckage has been identified since the Malaysia Airlines plane vanished on March 8, with objects retrieved from the desolate seas turning out to be fishing gear or flotsam.
Retired Australian air chief marshal Angus Houston, who is heading a new coordination centre in Perth, said it was the most challenging search and rescue operation he had ever seen and cautioned against expectations of quick success.
"I say that because the starting point whenever you do a search and rescue is the last known position of the vehicle or aircraft. In this particular case, the last known position was a long, long way from where the aircraft appears to have gone," he said.
Houston noted it took more than 60 years to find HMAS Sydney, which was sunk in the Indian Ocean in 1941 by a German warship, and the search for MH370 is "not something that's necessarily going to be resolved in the next two weeks".
"This could drag on for a long time but I think at this stage that it's very important to pursue all the leads," he added, as 10 planes and nine ships, some with helicopters, resumed the search in worsening weather.
- Black box -
Malaysia believes the flight, en route from Kuala Lumpur to Beijing with 239 people aboard, was deliberately diverted by someone on board and that satellite data indicates it crashed in the Indian Ocean.
Houston's appeal for patience contrasts with the angry demands of Chinese passengers' relatives who are desperate for firm information on what happened to their loved ones.
Australian vessel Ocean Shield, fitted with a US-supplied black box detector, left Perth Monday but is three day's sail from the search zone.
The battery-powered signal from the black box -- which records flight data and cockpit voice communications that could indicate what happened to the plane -- usually lasts only about 30 days.
Australian Defence Minister David Johnston admitted there was only a slim chance it would be found since any crash site remains unknown.
"We've got about a week (left), but it depends on the temperature of the water and water depth and pressure as to how long the battery power will last," he told Australian radio.
Authorities are scouring a massive expanse of ocean for floating MH370 debris. If found, they plan to analyse recent weather patterns and ocean currents to track back to where the plane went down.
Malaysian Prime Minister Najib Razak is expected in Perth on Wednesday to tour the air base being used as a staging post.
- Last words spoken -
The phrasing was different to the more casual "All right, good night" originally reported.
Aviation experts said the correction to the cockpit wording did not raise any red flags about possible pilot intent.
"There is plenty about Malaysia's handling (of MH370) over which questions may be raised, but I think in the scheme of things this is inconsequential," said Scott Hamilton, managing director of US-based aviation consultancy Leeham Co.
Shortly after the final message, communications were cut and the Boeing 777 vanished from civilian radar.
Malaysia insists it has been transparent, rejecting Chinese relatives' accusations it is guilty of incompetence or even a cover-up.
But there have been notable about-turns, including on the crucial sequence of events in the cockpit before the plane veered off course, and Malaysia's air force has been criticised for failing to intercept MH370 when it appeared on military radar.
Social media critics said the revised cockpit narrative raised further questions.
"The Malaysian government can't even get the cockpit sign-off right. Why would we expect they get anything else correct?" said one posting on Twitter.
A survey released Tuesday by Merdeka Center, Malaysia's leading polling firm, said less than half of Malaysians -- 43 percent -- were satisfied with the government's handling of the crisis, while 50 percent were dissatisfied.
The survey was conducted over two weeks to March 20. More recently, many Malaysians have rallied around the government, hitting back against criticism, particularly from China.
MH370 should lead to improvements in how aircraft are tracked in flight, International Air Travel Association head Tony Tyler said Tuesday in a statement released at an aviation conference in Kuala Lumpur.
"We cannot let another aircraft simply vanish," he said.
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