An expanded team of surveillance planes and ships is scanning a vast and remote section of the southern Indian Ocean for the wreckage of Malaysia Airlines Flight 370.
Australia's Joint Agency Coordination Center, which is leading the search, said up to 10 military planes, four civil jets and nine ships are involved in the multinational effort Friday.
No trace of the plane has been found, nearly four weeks after it vanished. Officials continue to try to narrow the search area, which currently stands at a staggeringly large 217,000 square kilometers.
Authorities are desperately trying to locate the crash site before batteries run out on the plane's flight data recorder, preventing it from transmitting a radio signal. The batteries usually last about 30 days.
On Thursday, an Australian ship detected what was initially thought to be a possible signal from the so-called black box. But it was later discounted as a false alert, possibly from a sea animal or interference from shipping noise.
The international search team said it remains committed to finding the wreckage, but officials have in recent days conceded that the mystery may never be completely solved.
The jetliner vanished without any distress calls on March 8 during a flight from Kuala Lumpur to Beijing. Officials have refused to rule out any possibilities, including hijacking, sabotage, or a mechanical malfunction.
Malaysian officials have ruled out foul play from any of the plane's 239 passengers, but continue to investigate the pilots and crew for possible wrongdoing.