Missing Malaysia jet anywhere from Kazakhstan to Australia

Checks into the background of all the Chinese nationals on board the missing Malaysian jetliner have uncovered no links to terrorism, the China's ambassador in Kuala Lumpur said Tuesday.

The remarks will dampen speculation that Uyghur Muslim separatists in far western Xinjiang province might have been involved with the disappearance of the Boeing 777 and its 239 passengers and crew early on March 8.

The plane was carrying 154 Chinese passengers, when Malaysian officials say someone on board deliberately diverted it from its route to Beijing less than one hour into the flight. A massive search operation in the Indian Ocean and beyond has yet to find any trace of the plane.

China's ambassador to Malaysia, Huang Huikang, said background checks on Chinese nationals didn't uncover any evidence suggesting they were involved in hijacking or an act of terrorism against the plane, according to the state Xinhua News Agency. Huang also that authorities in China had begun searching for the plane on its territory.

While the results of China's background checks seemed to remove one theory about the missing Malaysia Airlines Flight MH370, investigators were considering the possibility that the aircraft — which last made contact with the ground off eastern Malaysia with 239 people aboard — could have flown as far as Kazakhstan in Central Asia.

But Kazakh aviation authorities said Monday that the jetliner would have been detected if it had flown over the county’s territory and that they spotted the nine other Malaysia Airlines planes that made regular flights to and from Europe over their territory on March 8, the day Flight MH370 disappeared.  

"Even if all onboard equipment is switched off, it is impossible to fly through in a silent mode," the Kazakh Civil Aviation Committee said in a statement signed by the committee's deputy head, Serik Mukhtybayev.

"There are also military bodies monitoring the country's airspace," the statement said. "Even hypothetically thinking, before reaching Kazakhstan’s territory, this plane would have had to fly over other countries along its route, where the flight zone is also closely monitored, so we would have received information from these countries.”

Malaysia Airlines Chief Executive Ahmad Jauhari Yahya said Monday that it was unclear exactly when one of the plane's automatic tracking systems was disabled — appearing to contradict comments government ministers made during the weekend.

Suspicions of hijacking or sabotage hardened when officials said Sunday that the last radio message from the plane — an informal "all right, good night" from the co-pilot, Fariq Abdul Hamid — was sent after the plane’s Aircraft Communications Addressing and Reporting System (ACARS) had apparently been shut down.

Ahmad said Monday that while the last data transmission from ACARS — which gives plane performance and maintenance information — went out before that, it was still unclear when the system was switched off. That opened the possibility that both ACARS and the plane's transponders, which make the plane visible to civilian air traffic controllers, were severed later or at about the same time.

The search for the jet pushed deep into both the Northern and Southern hemispheres on Monday, as Australia scoured the southern Indian Ocean and Kazakhstan — more than 6,000 miles to the northwest — answered Malaysia's call for help in the unprecedented hunt.

John Young, manager of the Australian Maritime Safety Authority's emergency response division said, "The sheer size of the search area poses a huge challenge. A needle in a haystack remains a good analogy."

French investigators arriving in Kuala Lumpur to lend expertise said they relied on distress signals in their two-year search for an Air France jet that crashed into the Atlantic Ocean in 2009. But that vital tool is missing in the Malaysia Airlines situation because Flight MH370's communications were apparently severed deliberately before its disappearance more than a week ago, investigators say.

"It's very different from the Air France case," said Jean Paul Troadec, a special adviser to France's aviation investigation bureau. "The Malaysian situation is much more difficult."

Malaysian authorities have said that the jet was intentionally diverted from its flight path during an overnight trip from Kuala Lumpur to Beijing on March 8. Suspicion has fallen on the pilots because they were capable of making such a change, although Malaysian officials have said they are seeking background checks on everyone on the flight.

Malaysian police confiscated a flight simulator from the pilot's home on Saturday and visited the home of the co-pilot, in what Malaysian Police Chief Khalid Abu Bakar initially said were the first police visits to those homes. But on Monday the government issued a statement contradicting that account by saying police went to the pilots' homes as early as March 9.

Investigators haven't ruled out hijacking, sabotage, pilot suicide or mass murder, and they are checking the backgrounds of all 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.

Malaysian Defense Minister Hishammuddin Hussein said at a news conference Monday that finding the plane was still the main focus of officials’ efforts, and he did not rule out finding it intact.

"The fact that there was no distress signal, no ransom notes, no parties claiming responsibility — there is always hope," he said.

Malaysia's government, meanwhile, sent out diplomatic cables to all countries in the search areas, seeking their help in providing planes and ships for the search as well as to ask for any radar data that might help narrow the task.

Twenty-six countries are now involved in the search, which initially focused on either side of Peninsular Malaysia, in the South China Sea and the Strait of Malacca.

Over the weekend, Malaysian Prime Minister Najib Razak announced that investigators determined that a satellite picked up a faint signal from the aircraft about seven and a half hours after takeoff. The signal indicated that the plane was somewhere on two vast arcs stretching from Kazakhstan down to the southern reaches of the Indian Ocean.

Hishammuddin said Monday that searches along both the northern and southern arcs had begun, with countries from Australia north to China and west to Kazakhstan joining the hunt.

Had the plane gone northwest to Central Asia, it would have crossed over countries with busy airspace, and some experts believe the person in control of the aircraft would more likely have chosen to go south. However, authorities are not ruling out the northern corridor and are eager for radar data that might confirm or rule out that path.

The northern search corridor crosses through countries including China, India and Pakistan — all of which have indicated they have seen no sign of the plane.

The southern Indian Ocean is the world's third-deepest and one of the most remote stretches of water in the world, with little radar coverage.

Al Jazeera and wire services