The two red arcs show the possible routes after the jet went missing
US intelligence is focusing on the pilot and co-pilot's possible role in the plane's disappearance and are worried it may have landed somewhere to be used later as a weapon.
The Boeing 777-200's final 'ping' was picked up nearly seven hours after the flight vanished from air traffic control screens.
At first it was thought contact was lost less than an hour into its flight from Kuala Lumpur to Beijing on March 8.
But now investigators say a 'ping' was detected from one of two air corridors going north and south from the sea off Malaysia.
One is a northern route stretching thousands of square miles from northern Thailand to Kazakhstan and the other is a southern zone from Indonesia towards the southern Indian Ocean.
Green shows satellites that could have picked up the jet
"It was an intentional, deliberate act, to bring down this airplane. And the question is who is behind that."
He said if the plane was flown north towards Kazakhstan, it would probably have been picked up by radar.
"The other one is it landed in a country like Indonesia, where it could be used later on as a cruise missile, as the 9/11 hijackers did," he said.
Twenty five countries have now joined the search which has changed from shallow seas to large areas of land crossing 11 nations as well as deep and remote oceans.
Questioned by Sky News, one official said: "It is possible for the aircraft to be transmitting on the ground as long as there is electrical power to the aircraft's system."
In reaction, John Lindsay, former head of air safety at British Airways, told Sky News: "It would be a possibility and perhaps a probability that the aircraft is on the ground transmitting those signals.
"If this has been a very carefully orchestrated, pre-planned event then the aircraft and its passengers are the asset of the people who perpetrated this activity.
"It would be bizarre to destroy your asset by running out of fuel and crashing it anonymously into one of the oceans or a land mass without declaring what the point of the exercise is.
"The auxiliary power unit would have enough fuel to keep running for days and keep the plane powered up for some considerably longer period."
Investigators said contact was lost with air traffic controllers north of Malaysia, about 40 minutes into the flight.
They said someone on board turned off the two communication systems, the ACARS and transponder, and the plane was deliberately diverted west.
There are four lines of inquiry that authorities are focusing on - hijacking, sabotage, and personal and psychological problems.
Investigators are looking at pilot Zaharie Ahmad Shah and co-pilot Fariq Abdul Hamid's personal and religious backgrounds.
Police have been searching their homes and have also examined a flight simulator at one of the properties.
20 of those passengers were already employees of the company working on the cloaking device of then 8 were from China; couple of AWACKS could jam the ground radar installations then redirect the plane somewhere perhaps inside the Malaysia to unload the passengers, capture those scientist and getting rid of the rest.
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