The second 'black box' from the wreckage of a China Eastern Airlines Boeing 737-800 jet that crashed into a mountainside in southern China has been located.
But it will take up to a year, says the Civil Aviation Administration of China, to piece together a comprehensive narrative for what happened.
Flight MU5735 crashed on Monday, killing all 132 people onboard, mainland China's deadliest aviation disaster in 28 years.
Heading to coastal Guangzhou from the southwestern city of Kunming, the plane dived from cruising altitude around the time it should have started its landing descent. The dead included nine crew members.
The flight data recorder, which could shed light on the cause of the crash, has been sent to Beijing for examination and analysis, state media reported. The other black box - the cockpit voice recorder - was delivered to experts in the Chinese capital after being found on Wednesday.
It is too soon to determine the cause of the crash, and crashes are usually the result of a combination of factors, experts said.
The second black box was dug out of a slope at the crash site about 9.20am in muddy conditions, after rain in recent days.
The device, part of which was badly damaged, was recovered 1.5 metres (5 feet) underground and 40 metres (130 feet) from the point of impact, said Zhu Tao, head of aviation safety at the Civil Aviation Administration of China.
"Civil aviation investigators at the site confirmed that the storage unit of the flight data recorder has been found," Zhu told a news conference in Guangxi. "Parts of the recorder were seriously damaged, but the outside of the storage unit was in fairly good condition."
The crash was the deadliest since a China Northwest Airlines flight from Xian to Guangzhou crashed, killing all 160 people on board.
What are the rumours about why the plane crashed?
Monday's flight briefly appeared to pull out of its nosedive before resuming its plunge to earth, according to flight tracking website FlightRadar24. Its data showed the aircraft was plummeting 31,000 feet per minute.
The pilots did not respond to repeated calls from air traffic controllers and nearby planes during the rapid descent, authorities said.
The disaster has shocked China, sending social media into overdrive as netizens parsed what little was known for clues.
China's cyberspace watchdog ordered internet platforms and websites to clamp down on rumours, conspiracy theories and any online mockery of the disaster.
Since the crash, authorities have banned users and closed accounts to deal with more than 167,000 rumours, ranging from the deaths of seven directors of a company to divine prophesies of a plane crash by the end of March.
China is leading the crash investigation. The United States has also been invited to take part, as the Boeing 737-800 was designed and manufactured there.
The US National Transportation Safety Board said it was working with US and Chinese authorities to resolve visa and COVID-19 quarantine issues before participating.