Investigations into the disappearance of Malaysia Airlines flight MH370 have turned to who altered the plane's course by typing a complicated code into a flight management computer system.
MH370: Australia to search Indian Ocean
Tony Abbott says Australia has accepted a request from the Malaysian Prime Minister to assume responsibility for searching the Southern Indian Ocean for flight MH370.PT3M45S http://www.canberratimes.com.au/action/externalEmbeddedPlayer?id=d-34xgg 620 349 March 17, 2014
Possible reasons for turning the plane around include foul play or a mechanical fault that caused the pilots to attempt to turn back to their Kuala Lumpur base but then lose control and consciousness.
The news came as an Australian-led search began for the plane in a massive stretch of ocean west of Perth, but is likely to take weeks, authorities have said. The search began on Tuesday afternoon when an Australian P-3 Orion surveillance plane set off from RAAF Base Pearce outside Perth.
According to US officials quoted in The New York Times it was likely that whoever typed the keystrokes into a computer on a knee-high pedestal between the captain and co-pilot was knowledgeable about plane systems.
A screen on board Malaysia Airlines Boeing 777-200ER flight MH318 shows the plane's flight path as it cruises over the South China Sea from Kuala Lumpur towards Beijing, at approximately the same point when, on March 8, flight MH370 lost contact with air traffic controllers. Photo: Reuters
The fact that the turnaround was programmed into the computer reinforced the belief of US investigators - first voiced by Malaysian officials - that the plane was diverted and that foul play was involved, the paper reported.
The reprogramming of the computer happened before ACARS, the plane's automatic tracking system, stopped working. ACARS cut out about the same time oral radio contact was lost and the transponder also stopped.
Investigators are scrutinising radar tapes from where the plane departed because they believe they would show that after the plane changed its course, it passed through several pre-established "waypoints" which are virtual mile markers in the sky. That would suggest that the plane was under the control of a knowledgeable pilot, because passing through those points without using the computer would have been unlikely.
But there are other theories as to why the pilots would type the code into the computer to alter the plane's direction, including that it depressurised for some reason, and the pilots then lost consciousness, said Desmond Ross, an Australian commercial pilot and aviation security expert who conducted a review of Kuala Lumpur airport in 2005.
Renewed attention on what happened in the cockpit came after authorities in Kuala Lumpur backed away from a statement by Malaysia's acting Transport Minister Hishammuddin Hussein on Sunday that ACARS was shut down before the co-pilot told Kuala Lumpur ground control ''all right, good night''. Prime Minister Najib Razak had also previously said there was a high degree of certainty the system was disabled just before the plane reached the east coast of peninsular Malaysia, before the co-pilot spoke in a seemingly calm way.
Malaysia Airlines chief executive Ahmad Jauhari Yahya contradicted the information at a press briefing on Monday night, saying the final transmission by the co-pilot, Fariq Abdul Hamid, may have occurred before any of the communications systems were disabled. He said the ACARS system had worked normally at 1.07am but failed to send its next scheduled update at 1.37am. Mr Fariq spoke at 1.19am.
Mr Ross said that while the focus had been on what Mr Najib said appeared to be movements "consistent with deliberate action by someone on the plane", there were a number of possible explanations as to why the plane lost communication, turned back and flew on for more than seven hours.
One theory was that the aircraft depressurised for some reason, possibility an explosion causing a hole in the fuselage.
"The pilots quickly recognise the need to descend," said Captain Ross. "One of them starts to reprogram the flight management system and sets a low attitude and starts to reset the heading to turn back to Kuala Lumpur … however he passes out before completing the entries into the computer for the new heading. The aircraft climbs out of control due to the explosion on board and then stalls at somewhere between the cruising height and 45,000 feet.
"It falls out of control to the height the pilot had set into the flight management system but does not complete the turn back to Kuala Lumpur because the pilot had only partly entered the numbers … it flies off on an unknown path."
Captain Ross stressed that he had no direct knowledge of the investigation.