The black box was recovered five feet deep in the ground and about 130 feet away from the point where the plane crashed, Zhu Tao, director of the Office of Aviation Safety at the Civil Aviation Administration of China (CAAC), told a press conference on March 27.
Parts of the recorder were badly damaged, but the exterior of the data storage unit of the device appears to be in good condition, Zhu said, adding it has been sent to Beijing for analysis.
Flight MU5735 was cruising at an altitude of 29,000 feet after about an hour into its journey from the city of Kunming to Guangzhou. It lost more than 20,000 feet in a minute and briefly regained altitude for about 10 seconds before resuming its nose-dive into a hillside, FlightRadar24’s data show.
Flight data recorders store crucial details including airspeed, altitude, direction, and engine power. They can also record the position of wing flaps and whether the plane was flying by autopilot. Officials said on March 23 that the two black boxes of the crashed jet were manufactured by Honeywell, without specifying the models’ names.
CAAC News mistakenly reported the flight data recorder was recovered on March 25. Minutes later the report was removed, with state news outlet Xinhua saying it was untrue.
The country’s internet regulator has banned over 2,700 accounts and removed more than 279,000 posts deemed to be illegal and spreading rumors on social media platforms, including the Twitter-like Weibo and Quora-like Zhihu, China Cyberspace Administration said on March 26.
The investigation will be led by CAAC. It will also include a representative of the U.S. National Transportation Safety Board (NTSB) and representatives from Boeing and CFM, the General Electric Co.–Safran joint venture that made the engines. The NTSB has said that talks were ongoing with China to address COVID-19 quarantine requirements.
Investigators will look at the plane’s maintenance history, the training and record of the pilots, and weather data. They'll examine pieces of the wreckage for clues. Even the size of the debris field is important. When wreckage is spread over a very large area, it could indicate the plane was breaking up before hitting the ground.