China’s aviation regulator ​has not released an annual update on its investigation into a deadly China Eastern Airlines crash ‌for the second year in a row, letting the fourth anniversary pass without providing any insight into the cause.

On March 21, 2022, the China Eastern Boeing 737-800 jet plunged into a hillside in the southwestern region of Guangxi about an hour after takeoff, killing all ​132 people on board in China’s deadliest air disaster in three decades.

Global aviation guidelines call for an ​initial report within 30 days of an accident and a final one ideally within a ⁠year so the industry can learn lessons from what went wrong and work to improve safety.

Failing that, investigators ​are expected to issue statements on each anniversary, but the Civil Aviation Administration of China (CAAC) last provided an update ​in March 2024 and victims’ relatives remain in the dark about what caused the plane to nosedive from cruising altitude rather than land in Guangzhou as planned.

The regulator’s earlier updates were only a few paragraphs long, offering scant details but indicating there were no faults ​or abnormalities found in the aircraft or engines before takeoff from Kunming, or with the weather or communications.

The ​crew held valid licences, had adequate rest and passed health checks on the day of the flight, and there was no dangerous ‌weather ⁠or dangerous goods on board the plane, the regulator has said.

Investigators examined the China Eastern crew’s actions after finding no malfunctions, two people briefed on the matter said at the time. The pilots did not respond to repeated calls from air traffic controllers and nearby planes during the rapid descent, authorities said.

In May 2022, the Wall Street ​Journal reported that “black box” data ​indicated someone had intentionally ⁠crashed the plane, citing a preliminary assessment from U.S. officials.

CAAC had said it would release relevant information based on the progress of the investigation and also said speculation surrounding ​the crash had “gravely misled the public” and interfered with accident investigation work.CAAC and ​China Eastern did ⁠not respond to requests for comment.

The International Air Transport Association (IATA), a global airlines body, this month issued its 2025 safety report, which reminded carriers of their obligation to file final reports.

“Accident investigation helps us improve safety, but many reports are not ⁠published in ​a timely, complete, or accessible way. Some are not made public ​while others lack clear recommendations,” IATA Director General Willie Walsh said in a statement. “While compliance with this obligation is improving, anything less than 100% ​shortchanges everyone on opportunities to improve.”