Co-pilot spoke last words heard from MH370

Police and a multi-national investigation team may never know for sure what happened in the cockpit unless they find the plane, and that in itself is a daunting challenge.

Satellite data suggests it could be anywhere in either of two vast corridors that arc through much of Asia: one stretching north from Laos to the Caspian, the other south from west of the Indonesian island of Sumatra into the southern Indian Ocean west of Australia.

Kazakhstan, at the end of the northern arc, said it had not detected any "unsanctioned use" of its air space on March 8.

"Even if all on-board equipment is switched off, it is impossible to fly through in a silent mode," the Kazakh Civil Aviation Committee said in a statement sent to Reuters. "There are also military bodies monitoring the country's air space."

China, which has been vocal in its impatience with Malaysian efforts to find the plane, called on its smaller neighbour to "immediately" expand and clarify the scope of the search. About two-thirds of the passengers aboard MH370 were Chinese.

Australian Prime Minister Tony Abbott said he had spoken to Malaysian counterpart Najib Razak by telephone, and had offered more surveillance resources in addition to the two P-3C Orion aircraft his country has already committed.

"He asked that Australia take responsibility for the search in the southern vector, which the Malaysian authorities now think was one possible flight path for this ill-fated aircraft," Abbott told parliament. "I agreed that we would do so."

Malaysian Acting Transport Minister Hishammuddin Hussein said diplomatic notes had been sent to all countries along the northern and southern search corridors, requesting radar and satellite information as well as land, sea and air search operations.

The Malaysian navy and air force were also searching the southern corridor, he said, and U.S. P-8A Poseidon surveillance aircraft were being sent to Perth, in Western Australia, to help scour the ocean.

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