Initial Information on China Eastern Airlines flight 5735
On Monday, the 21st of March 2022, China Eastern Airlines flight 5735 crashed into mountainous terrain during a scheduled passenger flight from Kunming to Guangzhou in the People’s Republic of China.
There were 132 souls onboard with no survivors. The search for life continues in difficult terrain but after five days, it seems unlikely.
The aircraft was a Boeing 737-89P, a twin-engine, single-aisle passenger jet, which was registered as B-1791. It was delivered new to China Eastern Airlines, one of the three largest airlines in mainland China, in 2015. A spokesman for the airline stated that it was up-to-date on maintenance and no irregularities had been logged.
Flight 5735 departed Kunming Changshui International Airport, which serves the capital of the Yunnan province and is the hub for China Eastern Airlines, at 13:00 local time (0500 GMT). The estimated time of arrival at Guangzhou Baiyun International Airport in the Guangdong province was 15:05. The weather was cloudy but the visibility was good.
There were nine crew on the flight: three pilots, five cabin crew and a security guard.
The captain of the flight had 6,709 hours on type. The pilot listed as the first officer with 31,769 flight hours was one of China’s first commercial pilots and the most experienced pilot at China Eastern Airlines, where he was a flight instructor. He had trained over a hundred captains, including the captain of this flight. The pilot listed as the second officer was his student. This pilot had only 556 hours flight time and Chinese media have reported that he was on the flight for observation, so he may not have been anywhere near the controls.
The initial climb to cruise was uneventful and all Air Traffic Control interactions were described later as normal until the point where the flight crew stopped responding.
Halfway through the flight, at 14:17 local, the aircraft entered the control zone of Guangzhou. It is not clear to me whether the flight crew contacted the Guangzhou controllers, let alone whether they might have been given any instructions to change altitude or start their descent.
Three minutes later, at 14:20, air traffic controllers noticed that China Eastern Airlines flight 5735 was descending rapidly. They immediately attempted to contact the flight crew. There was no reply.
Flightradar24’s playback of the flight based on ADS-B data shows the sudden descent as starting at 06:20 UTC: the Boeing seems to plunge from 29,125 feet to 9,057 feet, with the next updates showing 6,525 feet, 4375 feet and, finally, 3,225 feet before the flight disappears. The descent took place over three minutes, with a ground speed of 450 knots reducing to 376 knots. Note that this is groundspeed, not airspeed, so as the aircraft’s trajectory became vertical, it wasn’t necessarily slowing down so much as losing forward momentum.
This is the data that is most often cited in the mainstream media. However, flightradar24 have published an analysis of the raw data which gives more information:
MU5735 departed Kunming at 05:16 UTC and reached a cruising altitude of 29,100 feet at 05:27 UTC. The flight continued normally until 06:20 UTC when the aircraft began a rapid descent to 7425 ft AMSL before recovering to 8600 ft AMSL. The aircraft then descended rapidly again. The last ADS-B message received by Flightradar24 from MU5735 was at 06:22:35Z.972 UTC at an altitude of 3225 ft AMSL.
If the ADS-B data reflects reality, then that recovery of a thousand feet is very interesting. It could be a sudden configuration change (pieces breaking off the aircraft) but it seems more likely that someone briefly managed to successfully arrest the descent before losing control again.
Two videos have been shared on social media as showing the final moments of the descent. ChinaAviationReview has shared both: CCTV footage from a local mining operation and dashcam footage with no attribution.
Dash cam footage pic.twitter.com/w8iOzHblXE
— ChinaAviationReview (@ChinaAvReview) March 21, 2022
The aircraft crashed at high speed into mountainous terrain near the city of Wuzhou in Guangxi. Local residents heard a loud explosion and reported a massive bamboo fire in the area. Local firefighters arrived at 15:05 with more being dispatched from outside the area at 16:40. The fire was finally extinguished at 17:25.
Once the fire was out, rescuers approached the site from three directions and found debris scattered around a deep pit scarred into the slope by the impact. Most of the wreckage was discovered within a 30-metre area around the impact site which is said to be almost 20-metres deep. The terrain is muddy and steep and the weather is wet: pumps have been installed to keep the pit from flooding. Access is limited to a single road.
Chinese News Service, a state news agency, has posted a video showing the crash site:
Updates are being published on CGTN’s live news page, the official English-language Chinese news service in Beijing, however, it says that they are still looking for possible survivors which seems unlikely. CGTN is also broadcasting a daytime stream from the search site; depending on when you view it, you may be seeing yesterday’s broadcast:
The Honeywell cockpit voice recorder was recovered on Wednesday about 20 metres from the main impact area. The bright orange exterior of the “black box” is severely damaged but the head of the Chinese aviation safety office described the unit as “relatively complete”. The CVR has been sent to Beijing; it has not yet been confirmed whether any data can be recovered as the memory chip is damaged.
The flight data recorder has not yet been found.
In an interesting twist, yesterday, a farmer discovered a 130 cm x 10 cm metal strip in a paddy located 10 kilometres away from the impact site. Investigators report that this fragment may have come from the accident aircraft. They have broadened the search area in hopes of finding more pieces of the aircraft which might explain what happened.
Aljazeera reports that the China Eastern group grounded its fleet of Boeing 737-800s, with 89% of the airline’s flights cancelled on the day after the crash. China Eastern Airline’s company report lists 289 Boeing 737-series in their fleet of 751 aircraft. Estimates of 737-800s in the fleet range from 109 to 225.
China has one of the best airline safety records in the world, with no major incidents in over a decade. Before the pandemic, it was considered one of the world’s fastest-growing aviation markets. Now, however, local media reports that people are cancelling their flights and opting for high-speed rail for domestic travel.
The Civil Aviation Administration of China (CAAC) has designated an emergency task force to investigate the crash. The NTSB in the US has been invited to take part in the investigation and has appointed a senior official as their representative in the accident inquiries. Boeing has offered the full support of their technical experts.
However, the government of the People’s Republic of China requires an antigen test fourteen days before the flight as well as two to three weeks quarantine upon arrival. This will hamper the ability of US investigators to meaningfully take part in the preliminary investigation.
Realistically, there are three likely root causes of this accident:
- Structural damage caused by faulty maintenance or some external factor
- A deliberate action by a member of the flight crew
- Sudden loss of power (bird strike or engine malfunction) followed by an inappropriate recovery by the flight crew
That’s a very broad range there which could range from anything from spatial illusions to catastrophic failure of a critical flight control surface to deliberate sabotage. Until the preliminary report is released (30 days after the accident), it will be difficult to narrow it down. If the flight data recorder isn’t found, it may be impossible.