China Eastern 737-800 crashes in Guangxi, southern China

alfa164 · Mon Mar 21, 2022 11:21 pm

flyingturtle wrote:
diseased wrote:
Sorry to repeat myself, but has anybody seen a weather radar depiction? A severe storm could also cause structural failure.

That's well impossible. Sudden changes in wind speed (and direction) is only a concern on approach. Severe hail or rainfall? That could impact the engines, but wouldn't cause an uncontrollable flight.

That brings up another issue: icing. Couldn't severe icing cause the plane to nose-down in a similar pattern as the one shown on the graphs?

c933103 · Mon Mar 21, 2022 11:23 pm

mila wrote:
Spaceship wrote:
Users on Chinese Social Media saying one pax missed the flight by a few minutes. New lease on life

So final passenger count should be 123 and 9 crew member a total of 132 souls on board.. RIP.

Yes one PAX was not allowed to fly due to not having the Covid pass!

There seems to be at least a dozen of different people on Chinese internet claiming themselves to be the last passenger who didn't board the flight.

Speaking of Chinese internet, this post from February 20 seems quite noteworthy:

Pilots are worried that they can't repay their home mortgage, the whole industry feel not assured in their work, people moving ins and outs have increased rapidly. What does this mean to an industry depends on safety?

https://www.chinadaily.com.cn/a/202201/ ... 83982.html A maintenance crew of Qingdao Airlines crushed to death (Jan 24 2022)

https://www.aeroinside.com/16680/china- ... -of-runway China Eastern flight touched down short of runway (Feb 9 2022)

https://www.sohu.com/a/523129276_260616 Kunming Airlines flight forgot to remove shear pin of landing gear causing the landing gear unable to retract and the flight have to return (Jan 30 2022)

https://www.shine.cn/news/metro/2202202145/ Then there is this incident of large scale cracks on windshield screen window (Feb 19 2022)

All these happened less than a year, Chinese civil aviation industry never had a safety record this worse, never! To have such embarrassing record, it feel sad as a member of the industry.

But, what would be next? No one know. Everybody are enduring. Waiting. Waiting for that flight. Waiting for that one chosen by god (read: the unfortunate one) to appear

sierrakilo44 · Mon Mar 21, 2022 11:31 pm

Dreamflight767 wrote:
This is in the comments of another website:

"Heard from expat captain that works in China.

Engine Failure, crew did not declare emergency - asked for descent.

ATC told to standby

Crew did not start drift down and flew the plane until stall."

Not sure how valid it is though. If the crew did not report engine failure, how would we know an engine failure occurred this early.

I’d like to know which website you got that from.

The descent rate was around 8,000 fpm, entirely plausible to be a stall as the descent rate of AF447 was about 10,000 fpm. On the other hand the extreme nose down attitude at the very end of the flight is not indicative of a stall (the aircraft would be almost horizontal). It may be a theory of the initial rapid descent from cruise altitude though.

And it’s not the first time lack of assertiveness has caused a Chinese crew to have mishandled an engine failure at altitude, fail to commence a descent at the appropriate time and suffer a high rate of descent as a consequence:

https://en.m.wikipedia.org/wiki/China_A ... Flight_006

So in my mind it’s a plausible theory. But only a theory until more evidence comes to light.

777Jet · Mon Mar 21, 2022 11:33 pm

AntonioMartin wrote:
Could it be a pilot suicide?

Yes.

zeke · Mon Mar 21, 2022 11:34 pm

sxf24 wrote:
DocLightning wrote:
TheMirror wrote:
Oh also, the Chinese Govt. grounding the 737 fleet rounds out to roughly 90% political, 10% safety. That's from my chair anyway.

But they did not ground the entire 737 fleet, only the MU fleet, right?

I don’t think there’s been official confirmation that any fleets have been grounded.

The airline grounded their own 737 fleet, they announced that yesterday. If you look at FR none of them are airborne and it’s the morning busy period.

flybucky · Mon Mar 21, 2022 11:37 pm

airplanecrazy wrote:
FWIW, this is what I see for the beginning of descent of recent flights that were cruising at 29,100 ft..

Great info. So nothing out of the norm in terms of when it started the descent, right? That's my current lead theory, that the descent triggered a mechanical failure.

sxf24 · Mon Mar 21, 2022 11:39 pm

zeke wrote:
sxf24 wrote:
DocLightning wrote:

But they did not ground the entire 737 fleet, only the MU fleet, right?

I don’t think there’s been official confirmation that any fleets have been grounded.

The airline grounded their own 737 fleet, they announced that yesterday. If you look at FR none of them are airborne and it’s the morning busy period.

Would you mind sharing a link? I don’t doubt it, but I’m interested in seeing the official confirmation.

c933103 · Mon Mar 21, 2022 11:41 pm

c933103 wrote:
mila wrote:
Spaceship wrote:
Users on Chinese Social Media saying one pax missed the flight by a few minutes. New lease on life

So final passenger count should be 123 and 9 crew member a total of 132 souls on board.. RIP.

Yes one PAX was not allowed to fly due to not having the Covid pass!

There seems to be at least a dozen of different people on Chinese internet claiming themselves to be the last passenger who didn't board the flight.

Speaking of Chinese internet, this post from February 20 seems quite noteworthy:
Pilots are worried that they can't repay their home mortgage, the whole industry feel not assured in their work, people moving ins and outs have increased rapidly. What does this mean to an industry depends on safety?

https://www.chinadaily.com.cn/a/202201/ ... 83982.html A maintenance crew of Qingdao Airlines crushed to death (Jan 24 2022)

https://www.aeroinside.com/16680/china- ... -of-runway China Eastern flight touched down short of runway (Feb 9 2022)

https://www.sohu.com/a/523129276_260616 Kunming Airlines flight forgot to remove shear pin of landing gear causing the landing gear unable to retract and the flight have to return (Jan 30 2022)

https://www.shine.cn/news/metro/2202202145/ Then there is this incident of large scale cracks on windshield screen window (Feb 19 2022)

All these happened less than a year, Chinese civil aviation industry never had a safety record this worse, never! To have such embarrassing record, it feel sad as a member of the industry.

But, what would be next? No one know. Everybody are enduring. Waiting. Waiting for that flight. Waiting for that one chosen by god (read: the unfortunate one) to appear

https://www.yicai.com/news/101306212.html
Also probably noteworthy is this testament from a China Eastern ground crew back in January.
"Although we have fewer flights in the past 2 years, but the time we MU staff spend in quarantine have created longest record. The entire year in the past, the focus of pandemic-fighting is to 'prevent inflow of virus', which aviation sector have to withstand bigger pressure than other sectors; and Shanghai accepted 1/3 of all inbound passengers, which mean compares to other airlines, we as the main hub airlines at Shanghai have to withstand greater pressue, in the past entire year, more than 210k quarantines have been logged, the longest one have been quarantined for 293 days. And we also have 237 overseas colleges in their position."

The report also mentioned that, MU since 2021 August, have started to quarantine and monitor their ground staff for 14+7+7 days in 10 batches of 6428 people, according to Chinese civil aviation authority requirement. 14+7+7 days mean that after staffs finished working, they need to quarantined at specific facility for 14 days, then quarantine at home for 7 days, and then another 7 days of health monitoring. For the staff being interviewed, it mean that, after ending the previous round of quarantine and monitoring on January 15, they have to go back to work on January 28 to handle the Chinese New Year traffic, and then they have to observe the quarantine, and they cannot return home until January 19 when they finished the initial 14 days of quarantine.

c933103 · Mon Mar 21, 2022 11:43 pm

sxf24 wrote:
zeke wrote:
sxf24 wrote:

I don’t think there’s been official confirmation that any fleets have been grounded.

The airline grounded their own 737 fleet, they announced that yesterday. If you look at FR none of them are airborne and it’s the morning busy period.

Would you mind sharing a link? I don’t doubt it, but I’m interested in seeing the official confirmation.

https://www.wenweipo.com/a/202203/21/AP ... 0fe12.html
http://www.news.cn/politics/2022-03/21/c_1128490743.htm
Report only say 737-800 subtype

DanielsBrawley · Mon Mar 21, 2022 11:45 pm

SBAer wrote:
JE-129 is also an interesting incident

South African investigators are probing the service history of a horizontal stabiliser trim motor after a serious out-of-trim incident occurred to a Boeing 737-800 approaching cruise altitude.

After taking off from Johannesburg bound for Cape Town on 2 September, the Mango aircraft was preparing to level off at 36,000ft in the vicinity of Kimberley, some 250nm southwest of its departure point.

Preliminary findings by the South African Civil Aviation Authority show that an out-of-trim stabiliser indicator illuminated, and the crew responded by disengaging the autopilot after consulting the quick-reference handbook.

But the aircraft then pitched nose-down, suggesting that a “significant” out-of-trim situation had developed, says the inquiry.
https://www.flightglobal.com/mro/stabil ... 02.article

The cause of the significant out of trim condition was likely due to the horizontal stabiliser that was not supplying long-term pitch control of the aircraft at TOC when the elevators were moved (nose up), consistent with the QAR data. The cause of the horizontal stabiliser not moving with the elevator trim could not be established as all horizontal stabiliser and elevator systems were checked and no fault was found. The aircraft was controllable after the crew had disengaged the autopilot and had overrode the trim switches, but the electrical system of the horizontal stabiliser trim was still unresponsive.
https://www.aeroinside.com/13773/mango- ... m-problems

This is interesting. Further up thread it was posted the aircraft had not flown in several days. Presumably maintenance? In the 9+ years I flew a 738 never had this scenario. I’m surprised the incident hasn’t received more scrutiny. It appears no definitive answer/cause/solution was determined. Head scratcher for sure.

flybucky · Mon Mar 21, 2022 11:47 pm

OldB747Driver wrote:
the hardover was only fatal if the aircraft speed was slow enough that full aileron could not counter the yaw-induced roll input. I don't see any evidence for that in the data either.

If there was a rudder hardover at high speed, and the pilots were able to counter it with ailerons, would they be able to land the plane? Isn't the rudder going to take over at lower speeds when they try to land?

777Jet · Mon Mar 21, 2022 11:59 pm

SBAer wrote:
flybucky wrote:
SBAer wrote:
Based on where this plane was in its journey, is it possible they initiated their decent right before the dive? Checking the flight from the previous day, it looks like they started roughly at the same point.

That's what I noticed too. One theory could be that they initiated the descent, which triggered some mechanical failure, leading to the crash.

This is where my head went too. Kind of reminds me Alaska 261 and the jackscrew issue.

Have there ever been jackscrew issues with the 737NGs? The Alaska 261 Mad Dog was only 8 years old at the time. However Alaska 261 was much more than just a jackscrew design issue as Alaska Airlines was cutting costs and increasing jackscrew lubrication intervals which contributed to the failure. IIRC the recovered Alaska 261 jackscrew had no lubrication on it. MU's maintenance of this aircraft will be looked into anyway.

How much recent flying time did the pilots have, or, did they not have many recent flying hours due to less Covid flying and were a bit rusty?

As for 737 rudder pcu issues of the past, IIRC the US Air and United flights, as well as the Eastwind incident in which the flight was saved, all occurred during approach when the aircraft was flying slower and closer to the ground. Could the same thermal shock (hot hydraulic fluid passing through a cold pcu) occur, that created the older 737 rudder issues, at high speeds / altitudes?

I'm still leaning towards this being intentional at this stage. Pilot, hi-jacker, bomb / explosion resulting in damage, who knows...???

Hopefully data can be recovered from the boxes...

jetwet1 · Tue Mar 22, 2022 12:00 am

I don't have much to add right now to the wild theories flying around, however in 4 hours we are having dinner with a QF 737 captain. You can be sure we will be talking this through. If he has any thoughts I will pass them along.

NearMiss · Tue Mar 22, 2022 12:06 am

AntonioMartin wrote:
Could it be a pilot suicide? And RIP to everyone.

That was the first thing I thought when I saw the first video. But then I saw the granular data chart and noticed that they actually managed to gain control and stabilize the airplane for a moment, only for it to nosedive again.

DanielsBrawley · Tue Mar 22, 2022 12:09 am

Spaceship wrote:
Firstly, a B737 is bigger and heavier than a Challenger. Secondly, no report so far of an A380 is the area. Lastly, he B737 lost more than 9,000 feet.

China doesn't operate in feet they operate in Meters, for 9000 meters is 27600 feet, the only two place that operate in China in Feet is the Hong Kong FIR and Taiwan FIR

Air airspace controlled by the Military in Mainland China.

Just don't count out an inflight break up either to due weather or hitting an military aircraft or drone.

It happened to the Delta Airlines B747-451 jet was severally damaged by ATC forcing the aircraft flying through bad weather over China 17th June 2015.

Will be interested to see if the FAA/NTSB/Boeing/CFM will be invited for the investigation, or will they be locked out due China zero Covid policy.

Why hasn't the crew and passenger list been released yet?

It will be interesting won’t it? I’m guessing they will not let the US or Boeing in until they have a reasonable idea of what we’re dealing with. Only when they’re sure it’s not a situation where they can “lose face” will they allow outsiders. I really hope I’m wrong but I’m afraid it will play out exactly like that.

zeke · Tue Mar 22, 2022 12:21 am

777Jet wrote:
AntonioMartin wrote:
Could it be a pilot suicide?

Yes.

Need to keep bias in check most flights in mainland China are not two crew. It is very common for Chinese mainland airlines even on domestic flights that they operate them with 3-4 cockpit crew. This is part of their pilot development program they have to observe flights, junior pilots often only have 250 hours when they start with the airline. Entry level pilots in these airlines could earn as little as US$1000/month salary.

Many years ago in Japan a Captain on a 737 went to the toilet just before top of descent, when he asked for entry back into the cockpit the FO reached around without looking and moved the control that they thought opened the door. They had their hand on the trim, and the aircraft went into a dive with similar high rates of descent to this aircraft. The SOP with Chinese airlines is that they have no toilet breaks within 20 minutes if TOD. However in the area this crashed there is a number of NE/SW routes and ATC often ask early descents for the traffic operating E/W, and ATC often ask for expedited descents.

Pilot suicide I think is very unlikely,

zeke · Tue Mar 22, 2022 12:34 am

DanielsBrawley wrote:
It will be interesting won’t it? I’m guessing they will not let the US or Boeing in until they have a reasonable idea of what we’re dealing with. Only when they’re sure it’s not a situation where they can “lose face” will they allow outsiders. I really hope I’m wrong but I’m afraid it will play out exactly like that.

Historically China has always invited outside agencies, the complexities are the covid flight bans and quarantine requirements which are very inflexible.

c933103 · Tue Mar 22, 2022 12:39 am

zeke wrote:
777Jet wrote:
AntonioMartin wrote:
Could it be a pilot suicide?

Yes.

Need to keep bias in check most flights in mainland China are not two crew. It is very common for Chinese mainland airlines even on domestic flights that they operate them with 3-4 cockpit crew. This is part of their pilot development program they have to observe flights, junior pilots often only have 250 hours when they start with the airline. Entry level pilots in these airlines could earn as little as US$1000/month salary.

Many years ago in Japan a Captain on a 737 went to the toilet just before top of descent, when he asked for entry back into the cockpit the FO reached around without looking and moved the control that they thought opened the door. They had their hand on the trim, and the aircraft went into a dive with similar high rates of descent to this aircraft. The SOP with Chinese airlines is that they have no toilet breaks within 20 minutes if TOD. However in the area this crashed there is a number of NE/SW routes and ATC often ask early descents for the traffic operating E/W, and ATC often ask for expedited descents.

Pilot suicide I think is very unlikely,

Is there any radio records?

DanielsBrawley · Tue Mar 22, 2022 12:39 am

zeke wrote:
DanielsBrawley wrote:
It will be interesting won’t it? I’m guessing they will not let the US or Boeing in until they have a reasonable idea of what we’re dealing with. Only when they’re sure it’s not a situation where they can “lose face” will they allow outsiders. I really hope I’m wrong but I’m afraid it will play out exactly like that.

Historically China has always invited outside agencies, the complexities are the covid flight bans and quarantine requirements which are very inflexible.

In the current environment I was thinking more geopolitical.

Flaps · Tue Mar 22, 2022 12:44 am

flyingturtle wrote:
diseased wrote:
Sorry to repeat myself, but has anybody seen a weather radar depiction? A severe storm could also cause structural failure.

That's well impossible. Sudden changes in wind speed (and direction) is only a concern on approach. Severe hail or rainfall? That could impact the engines, but wouldn't cause an uncontrollable flight.

This statement is incorrect. A few examples off the top of my head:

Braniff 250
Northwest 705
BOAC 911

zeke · Tue Mar 22, 2022 12:45 am

c933103 wrote:
Is there any radio records?

There will be, ATC along that route is very good, a number of larger airports and different control centres, with continuous ATC radar coverage.

brocky120 · Tue Mar 22, 2022 12:45 am

From the CCTV footage, it looks like the plane is briefly on fire, hard to see and no smoke (from we have seen anyway), may be incorrect, also looks like the stabiliser came off before it hit the ground. Also, could the rough altitude and vertical speed be due to a fight in the cockpit?

All speculation of course.

sierrakilo44 · Tue Mar 22, 2022 12:56 am

DanielsBrawley wrote:

In the current environment I was thinking more geopolitical.

A big possibility. Do you think the Chinese government wants Americans in China telling the world that the cause of this crash was not a problem with an American product, but a problem with a Chinese pilot or maintenance staff?

Unfortunately the geopolitical reality of the current world has made our ideal of an unbiased blame free crash investigation unfeasible.

Although it has happened before, don’t forget Egypt still claims to this day flight 990 was a mechanical failure.

log0008 · Tue Mar 22, 2022 1:20 am

c933103 wrote:
c933103 wrote:
mila wrote:
Yes one PAX was not allowed to fly due to not having the Covid pass!

There seems to be at least a dozen of different people on Chinese internet claiming themselves to be the last passenger who didn't board the flight.

Speaking of Chinese internet, this post from February 20 seems quite noteworthy:
Pilots are worried that they can't repay their home mortgage, the whole industry feel not assured in their work, people moving ins and outs have increased rapidly. What does this mean to an industry depends on safety?

https://www.chinadaily.com.cn/a/202201/ ... 83982.html A maintenance crew of Qingdao Airlines crushed to death (Jan 24 2022)

https://www.aeroinside.com/16680/china- ... -of-runway China Eastern flight touched down short of runway (Feb 9 2022)

https://www.sohu.com/a/523129276_260616 Kunming Airlines flight forgot to remove shear pin of landing gear causing the landing gear unable to retract and the flight have to return (Jan 30 2022)

https://www.shine.cn/news/metro/2202202145/ Then there is this incident of large scale cracks on windshield screen window (Feb 19 2022)

All these happened less than a year, Chinese civil aviation industry never had a safety record this worse, never! To have such embarrassing record, it feel sad as a member of the industry.

But, what would be next? No one know. Everybody are enduring. Waiting. Waiting for that flight. Waiting for that one chosen by god (read: the unfortunate one) to appear

https://www.yicai.com/news/101306212.html
Also probably noteworthy is this testament from a China Eastern ground crew back in January.
"Although we have fewer flights in the past 2 years, but the time we MU staff spend in quarantine have created longest record. The entire year in the past, the focus of pandemic-fighting is to 'prevent inflow of virus', which aviation sector have to withstand bigger pressure than other sectors; and Shanghai accepted 1/3 of all inbound passengers, which mean compares to other airlines, we as the main hub airlines at Shanghai have to withstand greater pressue, in the past entire year, more than 210k quarantines have been logged, the longest one have been quarantined for 293 days. And we also have 237 overseas colleges in their position."

The report also mentioned that, MU since 2021 August, have started to quarantine and monitor their ground staff for 14+7+7 days in 10 batches of 6428 people, according to Chinese civil aviation authority requirement. 14+7+7 days mean that after staffs finished working, they need to quarantined at specific facility for 14 days, then quarantine at home for 7 days, and then another 7 days of health monitoring. For the staff being interviewed, it mean that, after ending the previous round of quarantine and monitoring on January 15, they have to go back to work on January 28 to handle the Chinese New Year traffic, and then they have to observe the quarantine, and they cannot return home until January 19 when they finished the initial 14 days of quarantine.

Just want to clear something up, these rediclous measures only apply to international crews or those handling international freight. I've been an instructor for years teaching cadets for various Chinese airlines and have a handful I am still in contact with including at Eastern. Other than masking and plenty of PCR testing domestic crews don't face these severe restrictions.

Low hours and low pay during covid is a bigger issue, and unlike in the West, you're contracted to your airline for life so even if your only flying and being paid for 5 hours per month you can't go and get another job until covid blows over.

OldB747Driver · Tue Mar 22, 2022 1:24 am

flybucky wrote:
If there was a rudder hardover at high speed, and the pilots were able to counter it with ailerons, would they be able to land the plane? Isn't the rudder going to take over at lower speeds when they try to land?

Yes, they could land, and No to the second part - the procedure would be to remove hydraulic power/pressure to the rudder allowing it to slipstream out of the hardover position and land.

zeke · Tue Mar 22, 2022 1:24 am

sierrakilo44 wrote:
A big possibility. Do you think the Chinese government wants Americans in China telling the world that the cause of this crash was not a problem with an American product, but a problem with a Chinese pilot or maintenance staff?

Unfortunately the geopolitical reality of the current world has made our ideal of an unbiased blame free crash investigation unfeasible.

Although it has happened before, don’t forget Egypt still claims to this day flight 990 was a mechanical failure.

That is not the way accident investigation works, the state of design and manufacturer would be there under observer status only to provide technical support. They are not permitted to release any information unless approved to do so by the state of investigation.

I cannot point to a time where the NTSB has not followed this fundamental ICAO accident investigation framework when working with another country.

\

wjcandee · Tue Mar 22, 2022 1:32 am

zeke wrote:
Need to keep bias in check most flights in mainland China are not two crew. It is very common for Chinese mainland airlines even on domestic flights that they operate them with 3-4 cockpit crew. This is part of their pilot development program they have to observe flights, junior pilots often only have 250 hours when they start with the airline. Entry level pilots in these airlines could earn as little as US$1000/month salary.

Many years ago in Japan a Captain on a 737 went to the toilet just before top of descent, when he asked for entry back into the cockpit the FO reached around without looking and moved the control that they thought opened the door. They had their hand on the trim, and the aircraft went into a dive with similar high rates of descent to this aircraft. The SOP with Chinese airlines is that they have no toilet breaks within 20 minutes if TOD. However in the area this crashed there is a number of NE/SW routes and ATC often ask early descents for the traffic operating E/W, and ATC often ask for expedited descents.

Pilot suicide I think is very unlikely,

Old747Driver wrote:
(responding to question about rudder hardover preventing landing) No - the procedure would be to remove hydraulic power to the rudder allowing it to slipstream out of the hardover position and land.

Thank goodness that knowledgeable adults (i.e. pilots) have joined this thread. Thank you for your input.

kuhne · Tue Mar 22, 2022 2:09 am

I am always amazed at how it is easier to blame a person nobody knows (the pilot) for suicide, terrorism, or whatever before god forbid saying something could be wrong with the plane, and even then, we're always quick to point out it was probably poor maintenance from "x" country. I love this website but these types of posts always bring out the worst in people, one thread even mentioned how Chinese crews lack of assertiveness has brought down planes in the past (did that guy just generalize a lack of assertiveness of over 1.4 billion people? Or just flight crews?)

Anyway, I for one do not know what happened and would not like to speculate but if someone were to put a gun to my head and force me to come up with an answer I would say catastrophic malfunction of an engine or control surface, which then, of course, will be blamed on maintenance, the country, government, etc.

And if it ends up being pilot suicide, at least I'll feel good about blaming him...after the fact.

Speedy752 · Tue Mar 22, 2022 2:22 am

I thought rudder hardcover was only on the 737 classics? Didn’t the design change after that?

BowlingShoeDC9 · Tue Mar 22, 2022 2:55 am

Speedy752 wrote:
I thought rudder hardcover was only on the 737 classics? Didn’t the design change after that?

It was. People bringing up the rudder hard over incidents are purely speculating, as are people bringing up suicide, weather, poor maintenance practices, jackscrews, aliens, and the illuminati.

iAvgeek737 · Tue Mar 22, 2022 3:01 am

Assuming this was not an engine failure with undeclared emergency and it wasnt a rudder-hardover

Is it possible that this could be an American 587/Alaska 261 type situation in which one of the stabilizers became partially or completely detached from the aircraft prompting a dive like that?

SBAer · Tue Mar 22, 2022 3:13 am

777Jet wrote:
SBAer wrote:
flybucky wrote:
That's what I noticed too. One theory could be that they initiated the descent, which triggered some mechanical failure, leading to the crash.

This is where my head went too. Kind of reminds me Alaska 261 and the jackscrew issue.

Have there ever been jackscrew issues with the 737NGs? The Alaska 261 Mad Dog was only 8 years old at the time. However Alaska 261 was much more than just a jackscrew design issue as Alaska Airlines was cutting costs and increasing jackscrew lubrication intervals which contributed to the failure. IIRC the recovered Alaska 261 jackscrew had no lubrication on it. MU's maintenance of this aircraft will be looked into anyway.

Not that I can recall or can find. However, I posted a separate reply where I did find an incident with a 737-800 having a horizontal stabilizer issue that they were unable to determine the root cause. The issue originated at cruise altitude and resulted in a nose dive. viewtopic.php?f=3&t=1471347&start=250#p23227227

trnswrld · Tue Mar 22, 2022 3:14 am

Oh my gosh, can we pllleeaasse stop posting the “is it possible” posts. Yes, at this point literally ANYTHING is possible.

flybucky · Tue Mar 22, 2022 3:17 am

Does the Track (heading) FR24 granular data yield any clues? [graph]

* It was cruising at 100º.
* As soon as the rapid descent began, it starting veering to the left to 91º in the first 20s. The descent rate was around 30,000 fpm.
* The next 15s, it veered the opposite way to the right to 140º. The descent rate was still around -30,000 fpm.
* The next 25s, it veered the opposite way to the left to 81º. The descent rate was slowing down and reached 0.
* For the final 50s, the track was relatively stable between 73º-88º.

Does this either support or eliminate any theories?

One possible scenario:
* Starting the descent triggered a mechanical failure which caused the plane to roll left initially.
* Pilots compensated with a procedure that caused it to turn right, but it was still dropping at -30,000 fpm.
* Pilots tried something else that was able to recover the plane, reaching +8,400 fpm and 8,600 ft AMSL, and stable heading.
* May have stalled at 8,600 ft AMSL, and didn't have enough altitude to recover. Or the recovery put too much stress and caused additional mechanical failure.

billsalton92 · Tue Mar 22, 2022 3:24 am

flybucky wrote:
Dreamflight767 wrote:
This is in the comments of another website:

"Heard from expat captain that works in China.
Engine Failure, crew did not declare emergency - asked for descent.
ATC told to standby
Crew did not start drift down and flew the plane until stall."

Not sure how valid it is though. If the crew did not report engine failure, how would we know an engine failure occurred this early.

Why would the plane stall on one engine? Isn't one engine sufficient to continue flying normally?

Multi engine aircraft have a drift down altitude. In the event of an engine failure, the remaining engine needs denser air to provide sufficient power to hold altitude. This could be low teens, or sub-10000 depending on the engine and weight of the aircraft. It's exciting when your Piper Seneca loses an engine on a hot summer day with any sort of payload

yhmfan · Tue Mar 22, 2022 3:28 am

sxf24 wrote:
zeke wrote:
sxf24 wrote:

I don’t think there’s been official confirmation that any fleets have been grounded.

The airline grounded their own 737 fleet, they announced that yesterday. If you look at FR none of them are airborne and it’s the morning busy period.

Would you mind sharing a link? I don’t doubt it, but I’m interested in seeing the official confirmation.

I just checked FR24 and the 737s are flying around. MU5845 is one example.

So no grounding.

BowlingShoeDC9 · Tue Mar 22, 2022 3:47 am

yhmfan wrote:
sxf24 wrote:
zeke wrote:

The airline grounded their own 737 fleet, they announced that yesterday. If you look at FR none of them are airborne and it’s the morning busy period.

Would you mind sharing a link? I don’t doubt it, but I’m interested in seeing the official confirmation.

I just checked FR24 and the 737s are flying around. MU5845 is one example.

So no grounding.

The grounding is for the 738 fleet only. If you look on FR24 with China Eastern and B738 filters you see empty skies.

JayinKitsap · Tue Mar 22, 2022 3:52 am

zeke wrote:
Many years ago in Japan a Captain on a 737 went to the toilet just before top of descent, when he asked for entry back into the cockpit the FO reached around without looking and moved the control that they thought opened the door. They had their hand on the trim, and the aircraft went into a dive with similar high rates of descent to this aircraft.

It has to be something like this or someone getting in/out of the seat falls.

Pulling out of a steep dive would take the control surfaces to their maximum force, hinges or actuators are going to break, control being lost.

Impacting an object, unless right on centerline would cause a noticable turn, so unlikely.

cuban8 · Tue Mar 22, 2022 5:02 am

My two cents of speculation with the few bits and pieces of information we have at this time.
Aircraft entered over speed at high altitude and pilot(s) tried to get out of it and entered a stall. They managed to partially stabilize the aircraft, but re-entered a stall which they didn’t recover from.

Virtual737 · Tue Mar 22, 2022 5:20 am

flybucky wrote:
Dreamflight767 wrote:
This is in the comments of another website:

"Heard from expat captain that works in China.
Engine Failure, crew did not declare emergency - asked for descent.
ATC told to standby
Crew did not start drift down and flew the plane until stall."

Not sure how valid it is though. If the crew did not report engine failure, how would we know an engine failure occurred this early.

Why would the plane stall on one engine? Isn't one engine sufficient to continue flying normally?

Normal flying, no. It could continue flying for sure but not at a "normal" cruise altitude of 32k feet+. Single engine max altitude would be more like 24k feet depending on weight.

FluidFlow · Tue Mar 22, 2022 6:23 am

Do we know the history of the airframe? Were there previous incidents?

I still think it could be similar to ELAL1862 or JAL123, at least that due to bad maintenance a structural failure occured.

So the aircraft was at the point of initiating descent. So what are the options? Reduce thrust and AoA or reduce thrust and AoA and deploy spoilers for a faster descent.

Would it be possible that the spoilers only deployed on one side (due to some maintenance mistake) causing a large difference in lift. Pilots did not understand that fast enough and the aircraft banks more and more until inverting. Autopilot will try to hold course until it is too much. Autopilot disengages and the aircraft fully rotates to an inversion. This causes the aircraft to lose a lot of altitude and massive increase in speed.

Pilots react and partially bring the aircraft under control but the fast pull back and change from negative to positive climb rate either damages the aircraft and it drops from the sky or the pilots stal the aircraft and it drops from the sky (second steep dive).

GoSharks · Tue Mar 22, 2022 7:37 am

sierrakilo44 wrote:
And it’s not the first time lack of assertiveness has caused a Chinese crew to have mishandled an engine failure at altitude, fail to commence a descent at the appropriate time and suffer a high rate of descent as a consequence:

https://en.m.wikipedia.org/wiki/China_A ... Flight_006

So in my mind it’s a plausible theory. But only a theory until more evidence comes to light.

China Airlines is from a different country...

spacecadet · Tue Mar 22, 2022 7:51 am

flybucky wrote:
Does the Track (heading) FR24 granular data yield any clues? [graph]

Track and heading are not the same thing. Just as ADS-B data gives us ground speed rather than airspeed, it gives us ground track rather than heading. That's the equivalent.

You can't determine anything from those ground track numbers. They're actually fairly consistent for a plane that's clearly experiencing some sort of event. You would actually expect the ground track to vary with altitude for the same heading, due to the effect of wind variations both at different altitudes and in the different areas the plane is passing through. Combined with the fact that the plane seemed to trade a lot of its forward motion for downward motion (meaning its track would be more affected by wind), I wouldn't be surprised if the plane was on a constant heading the entire time.

SRQLOT · Tue Mar 22, 2022 7:52 am

I see a ton of previous crashes to compare, but has anyone mentioned the crash in russia from few years back? Wasn’t that a 737-800 also and the vid of that was also the airplane going down almost vertically. Unfortunately I do not remember the airline or the year it happened.

hongkongflyer · Tue Mar 22, 2022 7:52 am

bzcat wrote:
Blankbarcode wrote:
djm18 wrote:
Another fast descent scenario was GOL flight 1907 but it would have been evident, I presume, if there would have been some form of collision with some aircraft or device.

Honestly, a collision (and honestly a ton of other possibilities) is still on the table until we get a better idea of what pieces are --or aren't-- at the crash site.
A collision could explain things, it's still possible the other party was military for example. If the military isn't willing to disclose they're missing an aircraft, combined with an overcast day, and the potential other plane crashing somewhere more remote, it's possible no one else has noticed yet.

I don't believe any of the theories until there's more info of course, but it's always a possibility.

Collision is definitely a possibility. China's civilian airspace are often intruded by military use without prior notice or warning.

Civilian drones are not allowed in China (well, the kind that can fly to FL290 anyway) so if there was a collision with unknown flying object or aircraft, it is almost surely a military one.

Are you sure about the military usage you mentioned?
In the past 10 years, airlines' operations in China were seriously affected by Military activities which block the airspace for an extend period of time. We even got prior notice about the upcoming military activities and airlines would proactively cancel flights and rebook their passengers in advance. So your claim about China's civilian airspace are often intruded by military use without prior notice or warning is completely wrong.

flybucky · Tue Mar 22, 2022 8:02 am

spacecadet wrote:
Track and heading are not the same thing. Just as ADS-B data gives us ground speed rather than airspeed, it gives us ground track rather than heading. That's the equivalent.

Ah, I get it. Thanks for the explanation.

iamtom · Tue Mar 22, 2022 8:05 am

There have been a few unconfirmed posts reporting the plane may have reported an engine problem, but didn’t declare emergency. It’s possible that this could have lead to an un-contained engine failure that could have damaged the flight controls or compromised the structure of the aircraft leading to this loss of control.

Hopefully the data and voice data recorders will be operable and the families of these poor souls will at least get answers to what happened.

FluidFlow · Tue Mar 22, 2022 8:08 am

FluidFlow wrote:
Do we know the history of the airframe? Were there previous incidents?

I still think it could be similar to ELAL1862 or JAL123, at least that due to bad maintenance a structural failure occured.

So the aircraft was at the point of initiating descent. So what are the options? Reduce thrust and AoA or reduce thrust and AoA and deploy spoilers for a faster descent.

Would it be possible that the spoilers only deployed on one side (due to some maintenance mistake) causing a large difference in lift. Pilots did not understand that fast enough and the aircraft banks more and more until inverting. Autopilot will try to hold course until it is too much. Autopilot disengages and the aircraft fully rotates to an inversion. This causes the aircraft to lose a lot of altitude and massive increase in speed.

Pilots react and partially bring the aircraft under control but the fast pull back and change from negative to positive climb rate either damages the aircraft and it drops from the sky or the pilots stal the aircraft and it drops from the sky (second steep dive).

To come back to that:
IIRC there were reports about incidents caused by the autopilot disengaging in sitations were the aircraft was already very close to an unrecoverable state and the sudden disconnection paired with unawareness by the pilots caused an incident?

SomebodyInTLS · Tue Mar 22, 2022 8:26 am

SRQLOT wrote:
I see a ton of previous crashes to compare, but has anyone mentioned the crash in russia from few years back? Wasn’t that a 737-800 also and the vid of that was also the airplane going down almost vertically. Unfortunately I do not remember the airline or the year it happened.

Funny you mention it - that struck me as well. Tatarstan Airlines back in 2013 (that long already!?):

https://www.foxnews.com/world/investiga ... s-on-cause

viewtopic.php?t=564779

That was disorientation during landing IIRC, so not very comparable really.

bennett123 · Tue Mar 22, 2022 8:30 am

Thinking about FluidFlow's point.

If the autopilot will disengage at a certain point, is it possible to add a feature giving and audible or visual warning that you are within x% of that point.

Would allow the pilot to disengage and hand fly, as opposed to the autopilot simply saying 'I can't cope, here you try'.

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