The battery on one of two underwater beacons attached to the black boxes of missing Malaysia Airlines Flight 370 expired more than a year before the plane vanished, the Malaysian government said Sunday in an interim investigatory report.
That finding suggests that searchers listening for "pings" from the beacons on the flight data recorder and the cockpit voice recorder after the Boeing 777 went missing last March 8 with 239 people aboard may have never even had a chance of detecting a signal from one of the devices.
No wreckage from the plane has ever been found. Sonar-equipped boats continue to search for the aircraft more than 1,000 miles off the west coast of Australia.
The report issued Sunday, which is required under international aviation agreements, offered few fresh insights into the cause of the plane's disappearance. Even the battery issue, while perhaps pertinent to the question of why it has been so difficult to find the missing Boeing 777, does not bear on why the jet vanished in the first place.
In the year that the plane has been missing, much speculation has been focused on whether the captain, first officer or crew may have intentionally downed the plane. But the report released Sunday said neither the pilot, first officer or crew exhibited signs of personal or financial stress, medical problems or substance abuse that might suggest a motive for foul play.
Investigators reviewed closed-circuit TV footage of Capt. Zaharie Ahmed Shah on the day of the flight and three earlier flights and observed "no significant behavioral changes" or unusual mannerisms. They said Shah had three bank accounts and three cars and two houses and examination of his expenditures "indicated nothing unusual."
Kok Soo Chon, who led the investigation team, told Malaysia's official Bernama news agency that the sole objective of the investigation was to prevent future accidents or incidents, not apportion blame or liability.
More than 150 of the passengers aboard the flight, which was bound from Kuala Lumpur to Beijing, were Chinese citizens.
China's foreign minister, Wang Yi, said Sunday the search for MH370 would not stop. "The search for MH370 will continue," Wang said on the sidelines of the annual meeting of China's legislature. "Today must be a tough day for the family members," he added, according to Reuters. "Our hearts are with you."
But as Wang spoke, dozens of family members of missing passengers gathered at Beijing's Lama Temple amid a heavy police presence, tearfully demanding answers about the plane's location and the fate of their loved ones. Officers sought to keep some reporters from interviewing the demonstrators and asked at least one foreign reporter to leave the grounds.
Cheng Liping, a makeup artist whose husband, Ju Kun, was on the flight, held up a sign reading: "We will never give up! There is no home without my husband! My two sons need their father to return home safely!"
Like a number of other next-of-kin, Cheng wore a white T-shirt with a drawing of an airplane on the front and text that read: "Tell me, where is MH370 really?"
"It's been a year and we still have no answers," said Cheng, whose sons are 6 and 2.
Others in attendance signed petitions urging the governments of Malaysia, Australia and China to keep putting resources toward the search.
As for the beacon battery issue, Sunday's report made no significant comment on the lapse, but said the battery was not replaced on time because of a computer system used to track and call out maintenance issues had not been updated properly.
The battery on the beacon of the flight data recorder expired in December 2012, the report said. Such beacons are supposed to function for 30 days in water up to 20,000 feet deep after a crash to help searchers find the device.
Even if the beacon battery had failed, there was nothing in the report to suggest the flight data recorder itself failed or did not record the data it was designed to collect. If it is eventually located, investigators presumably will be able to analyze its data. The device records aircraft parameters from various systems and sensors.
The battery apparently was installed in 2008 and should have been replaced in 2012. The report said the oversight was not discovered until MH370 went missing and that since then, Malaysia Airlines had carried out a fleetwide record inspection on such beacons to make sure maintenance logs for other aircraft were updated properly.