US officials probing the missing Malaysia Airlines flight MH370 suspect the final "ping" from the aircraft was sent from a poisition above water, most probably the Indian Ocean.
Shortly after American officials revealed they had "new information" regarding the missing flight, the search efforts for the jetliner turned to the Indian Ocean.
A US official who is familiar with the investigation told the Wall Street Journal that the final communication - the "ping" - emerged from the Boeing 777 jet when it was cruising at a "normal altitude" above water.
It is unclear why the "pings" stopped abruptly and officials say it is possible that someone on board could have prevented their transmission.
However, none of the officials have revealed the specific path of the aircraft - although the present search location is opposite the flight's original route.
Malaysia Airlines officials have said they have not received such data.
The "ping" does not exactly send out data from the aircraft, but is seen as an attempt to establish contact. Although Malaysia Airlines did not subscribe to this optional service, the plane was said to be transmitting automatic signals five or six times during its extended flight, which is believed to have been nearly five hours after losing contact.
Another US authority, on condition of anonymity, described the "ping" by saying: "It's like when your cellphone is off but it still sends out a little 'I'm here' message to the cellphone network. That's how sometimes they can triangulate your position even though you're not calling because the phone every so often sends out a little bleep. That's sort of what this thing was doing."
The USS Kidd destroyer has also been deployed at the request of the Malaysian government by the US to aid the search operation in the Indian Ocean, the third-largest ocean on the planet.
After seven days of intense efforts from several nations, the plane still remains missing and no clues have been found to track the Beijing-bound airliner carrying 239 passengers and crew.
FLIGHT MH370 FACTBOX
Flight MH370 took off from Kuala Lumpur International Airport en route to Beijing at 00:41 on Saturday 8 March (16:41 GMT Friday).
About 50 minutes later, the aircraft lost contact with air traffic control.
No distress call was made.
On board, there were 12 Malaysian crew members and 227 passengers from 14 countries. That included 153 Chinese and 38 Malaysians.
Two Iranian male passengers, Pouria Nour Mohammad Mahread and Delavar Syed Mohammad Reza, were travelling on fake passports. Neither had any apparent links to terrorist groups.
No debris from the plane has been found in the international search.
At least 10 countries, including China, the US and Singapore, were using a total of 42 ships and 39 aircraft to search for the missing plane in the South China Sea, the Malacca Strait and the Andaman Sea.