Missing Plane: Southern Route 'More Likely'

Investigators searching for the Malaysia Airlines plane face a daunting task with thousands of square miles to scour.

The international hunt has now switched to focus on two flight corridors - as India suspends its search around the Andaman and Nicobar Islands and operations in the South China Sea are called off.

One of the areas officials are looking at is a northern route stretching from northern Thailand to Kazakhstan and the other is a southern zone from Indonesia towards the southern Indian Ocean.

It comes after a satellite communication with the jet, which disappeared over a week ago, indicated it flew for around seven hours, six more than was first thought.

The Malaysian government is in discussions with those countries where the plane could have flown over after it went missing.

They include India, Bangladesh, Pakistan, Tajikistan and Kyrgyzstan, and their intelligence agencies will be looking at radar to try to establish if they may have picked up the plane.

Early on March 8, someone on the jet turned off its two communications systems, known as ACARS and transponder, as it vanished from air traffic controller screens north of Malaysia. It was then deliberately diverted west.

Several experts have said a route along the southern corridor over the ocean was the more likely scenario.

This was because the northern one would have required the plane to travel undetected through numerous national airspaces in a strategically sensitive region.

But if it did land in the Indian Ocean it would pose enormous challenges for investigators to find the wreckage as well as the voice and data recorders.

This is because that ocean is one of the most remote places in the world and also one of the deepest.

Officials believe, based on the available data, the aircraft flew south until it ran out of fuel and crashed into the sea, Reuters reports.

Any debris from flight MH370 would have been widely dispersed by Indian Ocean currents in the week since it disappeared.

India air traffic controllers ruled out the northern route, saying it was "inconceivable" the plane flew undetected over Indian airspace towards Kazakhstan.

Even if civilian radars based in the eastern Indian city of Kolkata missed the plane, air force radars would have certainly picked it up, said air traffic controllers' guild secretary Sugata Pramanik.

"If an aircraft wants to avoid being seen, they can easily become invisible to a civilian radar by switching off the transponder that relays information about the plane," he told The Times of India newspaper.

"But it cannot avoid defence systems. The Indian Air Force has radars in multiple installations across the country and it is inconceivable that none of them spotted the odd blip with no flight clearance."