737-800 down in China

Blackjack Davy said:
Pretty sure german cars weren't responsible for the killing of hundreds of people...
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Not in single incidents maybe, due to the capacity of a car being significantly less than an airplane, but I bet if you tallied up every person killed in said cars, for the last 50 years, worldwide, it will come out at way more than the plane deaths.
 
Some opinions from pilots on an aircraft forum is this is likely stabiliser trim runaway. When they started the descent the trim will have started the nose down and it moved to an extreme position before the pilot started to correct which then applies a trim brake. If the trim goes too far it can’t be fully corrected by pulling back on the yoke and instead the pressure on the yoke needs to be reduced so the trim brake releases and then the trim can be adjusted. However when they did this they caused an over stress on the airframe as it created large positive and then negative g forces. The likely result was a partial break up of the aircraft such as losing a rudder which then caused it to dive into the ground.
 
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delta0 said:
Some opinions from pilots on an aircraft forum is this is likely stabiliser trim runaway. When they started the decent the trim will have started the nose down and it moved to an extreme position before the pilot started to correct which then applies a trim brake. If the trim goes too far it can’t be fully corrected by pulling back on the yoke and instead the pressure on the yoke needs to be reduced so the trim brake releases and then the trim can be adjusted. However when they did this they caused an over stress on the airframe as it created large positive and then negative g forces. The likely result was a partial break up of the aircraft such as losing a rudder which then caused it to dive into the ground.
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Like a manual version of the MCAS failure then
 
Could be

http://www.b737.org.uk/runawaystab.htm

On trim runaway Autopilot is disabled, and could be a 2 pilot effort to stabilise the trim. However the counter to this Airspeed would be reduced to reduce the effort manually on the trim. looking at the flight24 airspeed was almost constant if not more. there' s also trim cut out and the pilot can hold onto the stabiliser trim wheel if runaway continues.

But this is interesting

Recovery from a Severe Out of Trim
Accelerate or decelerate the airplane to an in-trim airspeed. If a recovery must be initiated from an extreme nose-down out-of-trim requiring a high pull force, an increase in airspeed may relieve enough of the elevator load and control displacement to permit manual trimming. Do not exceed speeed limitation. If a recovery must be initiated from an extreme nose-up out-of-trim requiring a high push force, a decrease in airspeed may relieve enough of the elevator load and control displacement to permit manual trimming. It should be noted that the relationship between airspeed change and trim change do not remain constant. As airspeed is increased, trim change requirements decrease.

In an extreme nose-up out-of-trim condition, requiring almost full forward column, decellerate, extend the flaps and/or reduce thrust to a minimum practical setting consistent with flight conditions until elevator control is established. Do not decrease airspeed below the minimum manouvring speed for the flap configuration. A bank of 30 degrees or more will relieve some force on the control column. This, combined with flap extension and reduced speed, should permit easier manual trimming.

It could be at the height of 8000 they were trying recovery of severe out of trim.
 
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Minor updates
Potential debris from the plane has been found 6 miles from the crash site (which is before it started descending) - https://www.scmp.com/news/china/art...&utm_medium=share_widget&utm_campaign=3171854

crash_site_10km_radius_158ba995e63b9c76476c0544c06918b8f4733101.jpg

source of image - https://www.pprune.org/rumours-news...35-accident-march-2022-a-11.html#post11205621

The NTSB has been invited to investigate the crash - https://www.reuters.com/article/chi...crash-probe-idINL2N2VQ1HO?edition-redirect=in
 
Blackjack Davy said:
Pretty sure german cars weren't responsible for the killing of hundreds of people...
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Some experts in vehicle saferty disagreed, Ralph Nader for example:

https://www.nytimes.com/1971/09/12/archives/volkswagen-found-unsafe-by-nader.html

WASHINGTON, Sept. 11 (UPI) —Ralph Nader urged today, that Volkwagen recall all of its three million cars to correct safety defects and said the VW Microbus “is so unsafe” it should be permanently barred from the road.

In a 200‐page report, Mr. Nader, the consumer advocate said “The Volkwagen. Beetle is the most hazardous car currently in use in significant numbers in the United States.”:

Volkwagen promptly denied the charge, contending that its products “meet or exceed all safety standards.” Mr. Nader said that the recall he proposed would cost Volkswagen $184million. He said that his conclusion about the Volkwagen was based on these factors:

“The danger of injury from the windshield, the weakness of the seat backs, the likelihood of the doors opening in a crash the consequent likelihood of passenger ejection, the dangerous location of the gasoline tank, the propensity of the gas cap and the gas lines to come off during a crash, steering column penetration in a frontal crash, the vulnerability of the doors to side impacts, extraordinary sidewind sensitivity and handling qualities which make the car unpredictable.”
 
Not an update but I know a number of people have been wondering how it is possible for a plane to lose so much altitude so quickly. Here is an example of a plane experience something similar. The pilot disengages auto pilot without fully understanding the current situation of the plane. This leads to the plane rolling and it begins to dive.


Edit: This video explains what happens to plane as it rolls
 
It appears this may have been a suicide. Unconfirmed right now, but I know people who are part of the expat pilot community in China and that's the source of the information for this.
 
The preliminary report is out.
For anyone who speaks Mandarin (i think) https://yenei.variflight.com/club/item/?id=3xcsz6lzz6xKddd256026b

Does not discuss the cause of the accident but states the facts of the accident.

Google translation below (source: https://www.pprune.org/rumours-news...35-accident-march-2022-a-23.html#post11218304)
On March 21, 2022, the Boeing 737-800 B-1791 of China Eastern Airlines Yunnan Co., Ltd. was carrying out the MU5735 Kunming-Guangzhou flight. When cruising in the Guangzhou control area, the cruising altitude of the self-route dropped rapidly from 8900 meters, and finally crashed in Guangxi Near Mocong Village, Conan Town, Teng County, Wuzhou City, Zhuang Autonomous Region. The plane disintegrated after hitting the ground, killing all 123 passengers and 9 crew members on board.

According to the provisions of the "Convention on International Civil Aviation", within 30 days from the date of the accident, the investigating organization country must send the investigation preliminary report to ICAO and participating countries. and conclusions.

At present, the "3.21" China Eastern Airlines MU5735 Aircraft Flight Accident Investigation Preliminary Report has been completed, and the report mainly includes factual information such as flight history, crew and maintenance personnel, airworthiness maintenance, and wreckage distribution.

The main situations are as follows:
The aircraft took off from Runway 21 of Kunming Changshui Airport at 13:16 Beijing time, rose to a cruising altitude of 8900 meters at 13:27, entered the Guangzhou control area along the A599 route at 14:17, and at 14:20:55 Guangzhou area control radar showed a "deviation" Command altitude" warning, the aircraft left the cruise altitude, the controller called the crew immediately, but received no reply.

At 14:21:40, the last recorded aircraft information by the radar was: standard pressure altitude of 3380 meters, ground speed of 1010 km/h, and heading of 117 degrees. Subsequently, the radar signal disappeared.

The accident scene is located in a valley running from southeast to northwest near Mocong Village, Conan Town, Teng County, Wuzhou City, Guangxi Zhuang Autonomous Region. A puddle with an area of about 45 square meters and a depth of 2.7 meters can be seen at the scene, which is determined to be the main impact point, located at 23°19′25.52″ north latitude and 111°06′44.30″ east longitude.

The debris of the aircraft wreckage was mainly found on the ground and underground in the azimuth range from 0° to 150° of the impact point. The trailing edge of the right wingtip winglet was found approximately 12 kilometers from the main impact point. There were traces of fire in the forest vegetation at the scene of the accident.

Major wreckage including horizontal stabilizer, vertical tail, rudder, left and right engines, left and right wings, fuselage parts, landing gear and cockpit parts were found at the scene. After all the wreckage was searched and collected from the scene, it was uniformly transported to a special warehouse for cleaning and identification, and placed according to the actual size and position of the aircraft, which was convenient for subsequent inspection and analysis.

After investigation
1. The qualifications of the flight crew, cabin crew and maintenance and release personnel on duty meet the requirements;

2. The airworthiness certificate of the aircraft in the accident is valid, the last A inspection (31A) and the last C inspection (3C) of the aircraft did not exceed the inspection time limit specified in the maintenance plan, and there was no fault report before the flight and short-term parking on the same day, and no fault reservation;

3. There are no goods declared as dangerous goods on board;

4. There is no abnormality in the navigation and monitoring facilities and equipment along the route involved in this flight, and there is no dangerous weather forecast;

5. Before deviating from the cruising altitude, the radio communication and control command between the crew and the air traffic control department were not abnormal. The last normal land-air call was at 14:16; the two recorders on the aircraft were severely damaged due to the impact, and the data was restored and Analysis work is still in progress.


In the follow-up, the technical investigation team will continue to carry out in-depth investigations such as wreck identification, classification and inspection, flight data analysis, and necessary experimental verification in accordance with relevant procedures, and scientifically and rigorously identify the cause of the accident.
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