Investigation turns to re-enactment for clues while experts study flight paths on pilot's home-built machine.
Investigators are using simulators to re-enact Malaysia Airlines flight 370 in a bid to see where it may have landed.
It has also been revealed that authorities have commissioned aviation experts to retrace flight paths practiced by pilot Zaharie Ahmad Shah on a simulator he built and used at his home.
A source close to the investigation told the Herald that the lack of cellphone or internet communication from passengers and crew indicated a possibility that MH370 could be in "remote, non-friendly territory".
"There is no evidence that the aircraft crashed, and if it is on land and there are survivors in areas where there is internet signal or cellphone reception, someone would have made contact by now," the source said.
Last night, the chief executive of Malaysia Airlines said the airline believed the co-pilot spoke the last words heard from the aircraft.
Ahmad Jauhari Yahya said investigations indicated it was the co-pilot, rather than the pilot, who calmly said, "All right, good night" to ground controllers.
Officials say those words came after one of the jet's data communications systems had been switched off, sharpening suspicions that one or both of the pilots may have been involved in the disappearance.
Investigators are using simulators to re-enact the flight to see where it may have landed, and did not believe the aircraft was flown by someone who wanted to crash it.
One of the reasons the jet could avoid commercial radar detection was because it was flying at an altitude of 1500m or lower. By sticking to a commercial route, it could avoid suspicions on military radar.
Kuala Lumpur's New Straits Times said the flying technique was called "terrain masking" and was dangerous, putting pressure on the airliner.
Investigators are trying to determine how far the aircraft may have flown, and possible landing sites.
"It's highly improbable that it landed anywhere where any of the 200 passengers could use their mobile devices," the source said.
The New Straits Times quoted sources as saying the probe would also focus on regions with disused airports equipped with long runways capable of handling large aircraft such as the 200-tonne Boeing 777.
Inspector general of police Khalid Abu Bakar said experts were retracing the flight paths practiced by Mr Shah, 57, on the flight simulator and other electronic devices seized from his home on Sunday.
US intelligence efforts were also focusing on Mr Shah and his first officer, Fariq Abdul Hamid, according to a senior US lawmaker.
"I think from all the information I've been briefed on ... that something was going on with the pilot," said Michael McCaul, chairman of the House Homeland Security committee. "I think this all leads towards the cockpit, with the pilot and co-pilot."
Malaysia Airlines New Zealand manager Dzulkifli Zakaria would not comment on the circumstances of Mr Shah visiting Auckland in 2012 or any other time. He said he was not allowed to speak about the situation and repeatedly denied knowing the captain or spending time with him.
Meanwhile, Malaysia's transport minister, Hishammudin Hussein, said the "nature of the search has changed".
"From focusing mainly on shallow seas, we are now looking at large tracts of land, crossing 11 countries as well as deep and remote oceans," he said.
Celebrated stuntman on Beijing flight
A stuntman who doubled for martial arts star Jet Li is among the passengers on a missing Malaysia Airlines flight.
Ju Kun's credits include the acclaimed martial arts epic The Grandmaster. He doubled for Li in Fearless and The Expendables.
Kun also worked on The Forbidden Kingdom and he was scheduled to work on the series pilot for Marco Polo, a joint Weinstein and Netflix production, at a studio in Malaysia before he boarded the flight to return home to Beijing.
A joint statement from the production partners said: "We are deeply saddened by the news about Malaysia Airlines Flight 370. Ju Kun, who was on board, was an integral part of our production team and a tremendous talent. Our thoughts and prayers are with his family at this difficult time."
The last update on Ju's verified Sina Weibo account was on February 24, when he posted a photo of himself from Pulai, Malaysia, saying: "New hairstyle. New mood".
* Investigators testing theory plane may have flown below 5000ft to avoid detection by commercial radar.
* Malaysian authorities want to investigate a theory that the Boeing 777 may have been to Taliban-controlled bases on the border of Afghanistan and North-West Pakistan.
* Indonesia, Burma, Thailand, India and Pakistan say their radar systems haven't detected any sign of the Malaysia Airlines aircraft.
* Investigators researching the backgrounds of the people who boarded Flight MH370 had found no passengers with aviation expertise, reports say.
- additional reporting Anna Leask, AP