As the search for the missing flight MH370 enters its 10th day with few clues as to its whereabouts, the New Straits Times said today the Boeing 777-200ER dropped 5,000 feet (1,500m) to evade commercial radar detection.

In an exclusive story, the government-backed paper said investigators analysing MH370’s flight data revealed that the 200-tonne, fully laden twinjet descended 1,500m or even lower to evade commercial (secondary) radar coverage after it turned back from its flight path en route to Beijing.

The Malaysia Airlines Boeing 777-200ER (9M-MRO) disappeared on March 8 with 239 people on board. Malaysian authorities said on Saturday the plane was deliberately diverted and its on-board transmission devices switched off to avoid detection.

Its last contact was at 8.11am north of the Strait of Malacca.

Investigators poring over MH370’s flight data had said the plane had flown low and used “terrain masking” as it flew over the Bay of Bengal and headed north towards land, the NST reported.

Officials, who formed the technical team, were looking into the possibility that whoever was piloting the jet at that time had taken advantage of the busy airways over the Bay of Bengal and stuck to a commercial route to avoid raising the suspicion of those manning primary (military) radars, the paper said.

“The person who had control over the aircraft has a solid knowledge of avionics and navigation and left a clean track. It passed low over Kelantan, that was true,” the NST quoted an anonymous official as saying.

“Terrain masking” refers to an ability to position an aircraft so there is natural earth hiding it from the radio waves sent from the radar system. It is a technique mostly used in aerial combat where military pilots would fly at extremely low elevations upon normally hilly or mountainous terrain to “mask” their approach.

Experts said flying a Boeing 777 in such a way would be dangerous, stressing the airframe and possibly causing those on board to be air sick and suffer from spatial disorientation.

Flight MH370 flew for an estimated eight hours and the authorities believe it would have flew over two additional countries besides Malaysia, although it's not clear which ones.

On Saturday, Prime Minister Datuk Seri Najib Razak said the search for MH370 would now expand to areas beyond Thailand to Kazakhstan and Turkmenistan in the north and beyond Indonesia in the south.

This was after satellite data placed the aircraft in one of two corridors: at the north stretching from northern Thailand to Kazakhstan, or at the south, from Indonesia to the southern Indian Ocean.

The NST quoting sources said the probe would now focus on regions with disused airports equipped with long runways capable of handling a plane like the Boeing 777.

Putrajaya has briefed envoys from nearly two dozen nations and appealed for international help in the search for the plane.

"The search area has been significantly expanded," acting Transport Minister Datuk Seri Hishammuddin Hussein said yesterday.

"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."

Investigations have also focused on the backgrounds of the pilots, crew and ground staff of those who worked on the missing jet.

On Saturday, Special Branch officers searched the homes of the captain, Zaharie Ahmad Shah, 53, and first officer, Fariq Abdul Hamid, 27.

Today, Reuters reports that the last words from the cockpit of missing MH370 – "all right, good night" – were uttered after someone on board had already begun disabling one of the plane's automatic tracking systems.

Both the timing and informal nature of the phrase, spoken to air traffic controllers as the plane was leaving Malaysian-run airspace could further heighten suspicions of hijacking or sabotage, it said.

The sign-off came after one of the plane's data communication systems, which would have enabled it to be tracked beyond radar coverage, had been deliberately switched off, Hishammuddin said yesterday.

"The answer to your question is yes, it was disabled before," he told reporters when asked if the ACARS system – a maintenance computer that sends back data on the plane's status – had been deactivated before the voice sign-off.

Background checks of passengers have drawn a blank but not every country whose nationals were on board has responded to requests for information, Inspector-General of Police Tan Sri Khalid Abu Bakar said. – March 17, 2014.