Officials searching for missing flight MH370 are investigating whether whoever was in control of the plane when it veered off course deliberately flew low to avoid detection by military radar.
Experts say so-called 'terrain masking' could explain why the plane was apparently able to avoid being spotted.
Ten days after the Malaysian Airlines jet disappeared, an international team of investigators is said to be probing the possibility that the plane hugged close to the ground to avoid detection.
The New Straits Times reported that after the plane took off from Kuala Lumpur then veered off course, its altitude fell to as low as 5,000ft. Reports suggest that while investigators believe the plane was most likely seized and intentionally diverted, they have not uncovered links to any militant groups.
Kuala Lumpur has backtracked on potentially crucial information about when an important communication system was switched off, the aircraft communications addressing and reporting system, or Acars, was switched off before the last verbal communication with the aircraft.
The conversation took place at 1.19am. "All right, good night," were the last words, which officials believe came from Fariq Abdul Hamid (27), the co-pilot.
The suggestion that the pilots had not mentioned anything untoward when the system had been switched off heightened a perception that they were involved in whatever went wrong. But yesterday officials said the system had been switched off between 1.07am and 1.37am. The jet was last seen as a "blip" on a Malaysian military radar at 2.15am.
The revelation by Malaysia Airlines chief executive Ahmad Jauhari Yahya means the pilots may not have been aware that part of their satellite system had been turned off.
Police have searched the homes of the pilot, Zaharie Ahmad Shah (53), and Mr Hamid but have reportedly found nothing unusual.
"It is likely that the distance it could fly (at a low altitude) would be as much as halved compared to a normal cruising flight. But technically there is no reason why the aircraft could not fly at a low altitude for a long time."
Chris Yates, a London-based aviation expert