MAS Airlines flight MH370 dropped to an altitude of 5,000 feet, or possibly lower, to defeat commercial (secondary) radar coverage after it turned back from its Kuala Lumpur-Beijing route on March 8.
Investigators are poring over the Boeing 777-200ER's flight profile to determine if it had flown low and used "terrain masking" during most of the eight hours it was missing from the radar coverage of possibly at least three countries.
Top officials, who make up the technical team that had been holed up from morning till late at night here, are looking at the possibility that the jetliner, carrying 239 people, had taken advantage of the busy airways over the Bay of Bengal. By sticking to commercial routes, the flight may not have raised the suspicion of those manning primary (military) radars of the nations it overflew. To them, MH370 would appear to be just another commercial aircraft on its way to its destination.
"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," said officials.
"It's possible that the aircraft had hugged the terrain in some areas, that are mountainous to avoid radar detection."
This technique is called terrain masking and is used by military pilots to fly to their targets stealthily, using the topography to mask their approach from prying microwaves. This type of flying is considered very dangerous, especially in low-light conditions and spatial disorientation, and airsickness could easily set in. The stresses and loads it puts on the airframe, especially an airliner of the 777's size, are tremendous.
