Hopes raised by recent detection of signals from the the missing Malaysian Airlines jetliner's black box has started to wither once again amid overpowering fear that the battery of the recorder on board may have died.
The five-week search campaign resumed on Saturday, a day after Australian Prime Minister Tony Abbott warned that signals picked up during the search in the remote southern Indian Ocean, believed to be "pings" from the black box recorders, were fading.
Malaysia Airlines Flight MH370 disappeared soon after taking off on March 8 from Kuala Lumpur bound for Beijing with 227 passengers and 12 crew on board, triggering a multinational search that is now focused on the Indian Ocean.
Search officials say they are confident they know the approximate position of the black box recorder, although they have determined that the latest "ping', picked up by searchers on Thursday, was not from the missing aircraft.
Batteries in the black box recorder are already past their normal 30-day life, making the search to find it on the murky sea bed all the more urgent. Once they are confident they have located it, searchers then plan to deploy a small unmanned "robot" known as an Autonomous Underwater Vehicle.
"Work continues in an effort to narrow the underwater search area for when the Autonomous Underwater Vehicle is deployed," the Australian agency coordinating the search said on Saturday, according to Reuters News Agency.
"There have been no confirmed acoustic detections over the past 24 hours," it said in a statement.
The black box records data from the cockpit and conversations among flight crew and may provide answers about what happened to the plane, which flew thousands of kilometres off course after taking off.
The mystery has sparked the most expensive search and rescue operation in aviation history.