On March 21, 2022, a Boeing 737 passenger plane crashed into a mountain. This was China Eastern Airlines Flight 5735 flying from Kunming to Guangzhou in the People’s Republic of China. All 132 people on board died in the accident.
This was the first fatal accident involving a Chinese carrier in almost twelve years. China’s commercial aviation safety record has been one of the strongest in the world.
The plane, a Boeing 737-89P registered in China as B-1791, was not yet seven years old and not up to date on maintenance. The flight took off slightly late from Kunming Changshui International Airport at 1:16 p.m. local time for a two-hour flight. The weather was cloudy but visibility was good.
There were three pilots in the flight deck. The captain had 6,709 flight hours. The pilot listed as first officer with 31,769 flight hours was one of the most experienced pilots at China Eastern Airlines, where he was a flight instructor and captain. The pilot listed as second officer had only 556 flight hours; China Eastern Airlines confirmed that it was there for observation and to gain experience.
We have no idea who was at the controls.
The aircraft was cruising at 29,100 feet and entered the Guangzhou control zone at this altitude at 14:17.
Three minutes later, at 2:20 p.m., air traffic controllers noticed China Eastern Airlines Flight 5735 descending rapidly. They immediately tried to contact the flight crew. There was no response.
Flightradar24’s flight reproduction based on ADS-B data showed that the sudden descent began at 06:20 UTC (14:20 local): the Boeing appeared to fall from 29,125 feet to 7,426 feet above mean sea level. The next update showed a brief recovery to 8,600 feet before descending again. The final update shows the aircraft at 6,525 feet, 4,375 feet, and finally 3,225 feet before the flight disappeared. The descent was done in three minutes.
China Aviation Review showed the following images of the accident: the first is said to be CCTV footage from a local mining operation, the second is dash cam footage without attribution.
Dash Cam Images pic.twitter.com/w8iOzHblXE
– ChinaAviationReview (@ChinaAvReview) March 21, 2022
The Boeing 737 crashed in mountainous terrain near Wuzhou, Guangxi. Local residents heard a loud explosion and reported a massive bamboo fire in the area. Local firefighters arrived at 3:05 p.m. and more were dispatched from outside the area at 4:40 p.m. The fire was finally extinguished at 5:25 p.m.
There were no survivors.
As the accident took place in the People’s Republic of China, the investigation falls to the Civil Aviation Administration of China (CAAC). The NTSB participated as an accredited representative of the state of design and manufacturing (United States), with technical advisors from Boeing, the FAA, and engine manufacturer CFM. In practice, this meant that when the CAAC’s own attempts to download the severely damaged flight recorders ran into problems, the storage modules were worked on jointly at the CAAC laboratory in Beijing and the NTSB recorder laboratory in Washington, with CAAC and NTSB engineers appointed as a joint team.
Of Ruibao News:
NTSB engineers reached a key diagnosis: the stutters, echoes, and digital noise on the first CVR download were not problems with the audio itself. The internal “address lines” of the chip were broken. As an analogy: the magnetic tape was still there, but the index that told the playback machine in which order to read it had been broken. NTSB rebuilt the connector: removed the casing, insulated it with Kapton tape, reshaped the bent pins one by one, and extracted the data again. All four channels (captain, first officer, observer, cockpit area microphone) were of “excellent” quality. The path from “completely unintelligible” to “excellent” was a team of engineers at a microscope workstation, straightening bent pins one at a time.
The NTSB transferred data extracted from the CVR’s four audio channels (rated “Excellent”) and produced a Combined Cockpit Voice and Flight Data Recorder Download Report, dated July 1, 2022. This was a factual report that described what was on the recorders, how it was recovered, and what condition the data was in. The NTSB then turned over the entire CVR to the CAAC and, as is normal practice, did not retain copies of the audio. However, they retained their FDR working files, on the basis that they would be needed to assist the CAAC in producing the final report.
That final report has never appeared.
The CAAC issued its 30 day preliminary report in Chinese in April 2022 and a interim report in March 2023, which concluded only that the investigation was continuing because the accident was “very complicated and extremely rare.” He two-year update in March 2024 was more substantial and stated that the pre-flight qualifications of the crew, maintenance staff, airport support staff and air traffic controllers had been in line with requirements, that there had been no anomaly in radio communications before the accident, that there were no hazardous weather conditions at the accident site and that there was no evidence of dangerous goods in the cargo or luggage.
What the CAAC has not said, in any update, is what they believe happened.
The third anniversary in March 2025 came and went without any updates, as did the fourth in March 2026. In May 2025, when a Chinese citizen submitted an open government information request requesting the investigation progress report, the CAAC refused, citing risks to “national security and social stability.”
In January 2026, a Chinese national filed a Freedom of Information Act request with the NTSB, requesting agency records about the investigation. The NTSB responded on April 29, 2026 with the recorder’s report and supporting materials. The applicant sent them to GitHub and Wikimedia Commons.
On May 1, the NTSB also published the registrar’s report to your FOIA reading room, confirming that the documents are authentic.
inside that registrar’s report is this key phrase: While cruising at 29,000 feet, the fuel changes in both engines moved from run position to cut position. (my bold)
The two switches are located side by side on the throttle quadrant and can be operated with one hand on the Boeing 737NG. The report confirms that both engines started and the autopilot disengaged. Figures 12 and 13 show the last 90 seconds of recording, which even without the NTSB analysis looks pretty damning.
Figure 12 plots the last 90 seconds of FDR data. During the first 60 seconds the plane is in cruise and the tracks are flat. Then, in the last 30 seconds, both elevators are deflected substantially downward and both control columns are pushed forward – a sustained nose-down command from the cockpit. Both control wheels spin wildly over a wide range, oscillating during descent, and the ailerons reflect those inputs. The rudder remains practically neutral until a strong deflection occurs at the end. The pressure altitude drops from 30,000 to approximately 25,000 feet above the visible window, and the airspeed increases sharply as recording ends.
Please note that none of this stated in the NTSB report; The only evidence of a nose-down order exists in the images of the FDR results. We do not know the circumstances on the flight deck. The NTSB text focuses on FDR’s recording that ended less than half a minute after the fuel switches were moved to CUTOFF:
The data stopped with the aircraft descending to approximately 26,000 feet. They did not capture the rest of the descent and the final sequence of the accident. In investigating the reason for the premature end of the flight data, it was discovered that while cruising at 29,000 feet, the N2 values of both engines rapidly decreased below the point at which the generators shut down. The FDR has no battery backup, so without power from the plane’s generators it will shut down. This is different from the CVR, which has a battery backup and can continue recording for at least 10 minutes after the loss of the aircraft’s generators. In searching for the reason why the N2 engine dropped below the generator cut-out speed, it was found that while cruising at 29,000 feet, the fuel switches on both engines moved from the run position to the cut-off position. Engine speeds decreased after fuel switch movement.
The report does not analyze the extracted data or propose probable cause.
Immediately after the accident, a popular conspiracy theory on Chinese social media was that the accident was a murder-suicide carried out by the captain, and that the experienced first officer (rumored to be his former instructor) was powerless to stop him.
The CAAC has denied the theory in its entirety without offering any alternative explanation.
However, according to the document released by the FOIA, it certainly appears that a person on the flight deck deliberately shut down the engines and that, apart from a very brief recovery at the start, no pilot was able to pull the plane out of the dive.
As of this writing, the CAAC has not made any public comments. CNN confirmed that they contacted CAAC and China Eastern but did not receive a response. State media has not addressed the FOIA statement. To be fair, the news broke during the May Day festive period, but the silence on this story is nothing new.
It bothers me that a pilot cutting fuel appears as a major cockpit issue in four of the recent cases we have discussed or am in the process of writing about (Transair 810 (July 2021), China Eastern Airlines Flight 5735 (March 2022), Air India 171 (June 2025), and Jeju Air 7C2216 (December 2024)).
