The needle-in-a-haystack hunt for a missing Malaysian airliner spread to the vast Indian Ocean Friday after the White House cited "new information" that it might have flown for hours after vanishing nearly seven days ago.
Multiple US media reports, citing American officials, said the Malaysia Airlines Boeing 777's communication system continued to "ping" a satellite for a number of hours after it disappeared off radar with 239 people aboard, en route from Kuala Lumpur to Beijing.
"It's my understanding that based on some new information that's not necessarily conclusive, but new information, an additional search area may be opened in the Indian Ocean," White House spokesman Jay Carney said.
"The USS Kidd is transiting the Strait of Malacca en route to the Indian Ocean," a US Navy official told AFP, referring to a guided-missile destroyer initially deployed to the Gulf of Thailand on the other side of Malaysia's coast.
It was the latest in a series of tantalising leads that have pulled the search for flight MH370 in multiple directions and deepened what is fast becoming one of the biggest mysteries in modern aviation history.
"I can't think of any other incident like this where there is so little clue as to what actually happened," said Ravikumar Madavaram, an aerospace consultant at Frost and Sullivan Asia Pacific.
The new thrust opens an additional search front of daunting magnitude. The Indian Ocean is the world's third largest with an average depth of nearly 3,900 metres (12,800 feet).
It is like going "from a chessboard to a football field", Commander William Marks of the US 7th Fleet told CNN.
Marks insisted the search remained coordinated with the Malaysian authorities and that the US Navy was "not out here freelancing".
Malaysia has yet to react publicly to the latest US information, but a spokesman for the search response effort said the government was aware of the media reports and White House comments.
Malaysia Airlines said in a statement that it had "nothing further to add."
- 'Unprecedented' challenge -
The lack of results so far has created a volatile mix of grief, anger, frustration and speculation that the Malaysian authorities have struggled to control.
The government has stressed the "unprecedented" nature of the challenge, with the search parametres expanding daily and the focus swinging wildly from the east to the west of the Malaysian peninsula.
The Boeing 777 that vanished early Saturday over the South China Sea with no indication of distress has one of the best safety records of any jet. The airline also has a solid record.
The explanation void has been filled with a host of theories that include a mid-air explosion, terrorist act, catastrophic technical failure or rogue missile strike.
"There are so many stories swirling around. This morning one man told me the plane had landed in Africa," said Subramaniam Gurusamy, a 60-year-old Malaysian security guard whose son was on the flight.
"How am I going to explain to my grandchildren that nobody knows where their father is?" he told AFP.
Adding to the anguish of relatives -- most of whom are Chinese -- has been the succession of false leads, mixed signals, and miscommunication between the various countries involved in the hunt.
Malaysia on Thursday denied that Chinese satellite imagery had picked up wreckage in the South China Sea.
The Wall Street Journal, Washington Post and major US networks have all cited unidentified officials as saying the plane continued to emit signals via satellite "pings" for four or five hours.
The last signal was sent from over water, at a normal cruising altitude, the Journal cited investigators as saying.
Gerry Soejatman, an independent aviation analyst based in Jakarta, was sceptical that the plane could have flown undetected to the Indian Ocean given the number of military radars operated in the region by Malaysia, India, Thailand and Indonesia.
"How could it get past all of that?" said Soejatman. "And if it did, how many people in the military are going to lose their jobs?"
- 14-minute gap -
ABC news said US investigators believe the aircraft's data reporting system and its transponder -- which reports its position in flight to ground-based radar -- shut down separately.
The 14-minute interval suggests they may have been deliberately disabled or at any rate did not fail as a result of a catastrophic airframe incident, the US network said.
Coupled with Malaysian radar data indicating that the plane may have inexplicably started to turn back, the sequential shutdown could lend credence to the theory of a cockpit takeover.
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."
The plane lost radar contact at around 1:30 am, less than an hour after take-off, according to Malaysian officials.
They have confirmed that the last words heard from the cockpit were a relaxed "Alright, good night" as the plane was due to pass from Malaysian to Vietnamese air traffic control. The night was clear and the weather was fine.