Kuala Lumpur: Sceptical aviation analysts questioned on Friday the notion that a missing Malaysian airliner may have flown thousands of kilometres off course into the Indian Ocean, crossing undetected over a sensitive region bristling with military radar.

While hard to square with a number of ground realities, the theory appeared serious enough for the US Navy to mobilise valuable assets to investigate further, after the White House cited “new information” that the plane might have flown for hours after vanishing over the South China Sea.

“For an aircraft to just absolutely disappear at this level of technology in this age over a very busy sky of Southeast Asia is totally incongruous,” said Neil Hansford, chairman of leading Australian airline consultancy Strategic Aviation Solutions.

“But you have to wonder, why is the USS Kidd steaming to the Andaman Sea at 33 knots...because if the aircraft is anywhere it’s probably in the South China Sea or the Gulf of Thailand.”

A US Navy official said the destroyer USS Kidd was being sent to the Indian Ocean — on the opposite side of the Malaysian peninsula from where contact was lost — to investigate.

The shift in focus came as multiple US media reports, citing American officials, said that flight MH370’s communication system continued to “ping” a satellite for up to four hours after it disappeared en route from Kuala Lumpur to Beijing.

The reports amplified on Malaysia’s belief, based on a radar sighting, that the plane may have mysteriously turned back towards Kuala Lumpur just over an hour into its flight when no technical problem was apparent, on a calm night in fine weather.

Hansford said all the information he had seen pointed to a sudden, catastrophic event such as a mid-air explosion. He balked at the idea of the plane flying on for more than four hours through various national airspaces.

“An aircraft, without any transponders on, going over the top of anybody’s airspace would have become a military incident and somebody would have done something,” Hansford said.

Southeast Asia, and particularly the South China Sea, is a hotbed of bitter territorial disputes that are the subject of round-the clock surveillance by the competing parties.

Flying from the point where radar contact was lost to the Indian Ocean would have taken the plane through airspace monitored by Malaysian, Thai, Vietnamese, Chinese, Indonesian and Indian military radar.

“How did it get past all of that?” said Gerry Soejatman, an independent aviation analyst based in Jakarta.

One possibility is that the radar systems did pick something up, but it was unclear, and there was a reluctance to flag up data that would also reveal details about military radar capabilities.

“Defence is not only about having the capability but also not disclosing what capabilities you don’t have,” said David Kaminski-Morrow, the London-based air transport editor for Flight International.

“I am sure there is a lot of discussion in the back rooms on what information you want to put out there to help search for the aircraft, and what you don’t want out in the public domain,” he said.

Neither the US Navy nor White House has detailed the source of the intelligence that led to the redeployment of the USS Kidd.

The confounding mystery has fuelled a host of contending scenarios, including a mid-air explosion, terrorist act, catastrophic technical failure, pilot suicide or rogue missile strike.

The idea that it flew for hours, and thousands of kilometres, over the Indian Ocean would appear to lend credence to the notion of some sort of cockpit takeover.

The theory has gathered further weight from other unconfirmed reports that the plane’s two main automated communication systems shut down 14 minutes apart — suggesting this was done manually rather than caused by an explosion or other sudden catastrophic event.

But Soejatman said the time lag could have been the result of a fire.

“We have seen cases where there have been cockpit fires, and then the systems go down one by one,” he said. “It doesn’t necessarily have to be deliberate.”

Several analysts noted that speculation was being fuelled by the public’s widespread disbelief that a modern passenger plane carrying 239 people could vanish without trace — in an age of instant communication where smartphones have brought advanced technology into everyone’s pockets.

Although it has been almost a week, Paul Yap, an aviation lecturer at Temasek Polytechnic in Singapore, argued that the search was “still in its very early days” and that expectations had to be re-calibrated.

“The unusual problem and maybe the most important one in this case is that there is nothing that can tell them exactly how to deploy their resources,” he said.

“I know that is frustrating to hear...especially for the families, but right now that is the reality.”