China Eastern 737-800 MU5735 accident March 2022

[KAPAC]

Has the tail section been found ?

[agird]

Originally Posted by Matt48

Never attribute to racism that which can be explained by bad practice.

​​​​​​
How do US vs Chinese fatal crashes match up over the last decade?

[fdr]

Originally Posted by Compton3fox

Looking at the last data points: GS 376kts VS 30976 ft/min = ~305 kts. Decent angle is arctan(305/376) = 39 degrees. <please check my maths!> Based on the video evidence, it suggests that AOD increased markedly in the very last phase of the decent. Maybe up until this point, the A/C was relatively intact but suffered some significant break up close to the ground.

your maths is about right, and the aircraft has a resultant TAS down the flight path of 484 kts, At the lower levels that is an IAS of around 460-475 roughly, which is about 100kts over the Vne of the plane. At very high mach numbers, above the height where a change in the descent occurred to a momentary apparent recovery, the b737 wing reduces lift for a given AOA from the development of strong normal shock on the underside of the wing. a normal shock at high mach is expected, the 737 has a visible shock at around 0.78M, the Classic had one quite observable at at around 0.735. On the top, at speeds over MMo, the shock on the bottom of the wind results in a rapid loss of lift for a given AOA, which results in a decaying flight path, or a pretty hefty increase in AOA needed to maintain level flight.

Adam Air DHI 574, and Silk Air reached speeds higher than this aircraft, but both of those had very odd reasons for the upset. Adam Air was not far removed from Air Asias bad day out for causation. The usual testing limit for Mdive is around 0.06M above the proposed MMo, roughly. The B737 is not much fun at taht but it will do it, but 100kts over Vmo is a tall ask for the aircraft. The increased AOA needed to effect a recovery results in very high buffet and that is one of the items that impacts flutter boundaries.

The simulators that are certified for flight training do not properly represent the aircraft at speeds well in excess of Vmo/MMo, they give a sense of comfort that the MACH/CL, and MACH CM data does not support, the trim change is observable in the MMo-Md dive data. Back in the dark ages this was described as Mach tuck, and the explanation out of the AP3456A was related to the shock foot movement rearwards.... yes, that does occur, but the tuck comes from the development of the shock on the bottom of the wing, and that has a very abrupt loss of CL for the trimmed AOA, and that results in a stunning Cm change. The above just suggests that getting nose low in a jet transport goes bad pretty quickly, and the simulator does not have great fidelity for training in that area. For the occasions that I did tests out beyond MMo to Md the recovery was of enough concern that the flights were planned to have a high thrust level in the descent, so that if the tuck was excessive, a speed reduction from reducing thrust could be made. Some planes are just beautiful, like the Falcon, it is impeccable to very high speeds, with full authority without buffet. The B737 Classic has buffet that was odd given the rule, and the NG has a normal envelope that essentially alters to achieve compliance of the rule, through the little orange line that starts to drop down below the MMo indication, same for a few others, and that gives the compliance to the rule, albeit at a mach a little lower than the nominal MMo. In upsets, where the ATR is engaged, the thrust comes back rapidly to idle. If that hasnt occurred, then more has happened than can be explained by a simple upset. That info resides in the engine EEC memory chips, which have some possibility of having survived. The CVR and DFDR of this aircraft probably survived the average deceleration but any heavy structure that impacts them in the deceleration would have way above the 3400g test levels. The average deceleration would be around 2000-2100g, its about 50/50 the FDR or CVR will have taken higher impact loads.

All in all, would be surprised that the plane in this case was the trigger of the event, and an upset can occur without substantial crew error, or any action by the crew. An upset in severe weather can put the plane into a position that care is needed. The odd thing is that the most significant factor in the recovery of a high speed jet upset is the detection-recognition time of the crew before an effective recovery action is commenced. The only exception that comes to mind on that is the stunning survival of the B747 of CAL on its way to the USA that held together well beyond where it should have failed, it was pretty daggy by teh time it got to California, but it didn't splash down.

[krautland]

Originally Posted by agird

​​​​​​
How do US vs Chinese fatal crashes match up over the last decade?

10 years without a fatal incident in China. There were two fatalities in the same period in the US.

https://news.cgtn.com/news/2022-02-2...Pra/index.html

https://www.airlines.org/dataset/saf...-air-carriers/

China and the US are very close in number of system seats. China briefly was ranked first during Covid but that has since changed in favor of the US again.
Change could be temporary though as China is building a ton of new mega airports and is set to add 8,000 new 100+ seat aircraft in the next 20 years.

https://centreforaviation.com/analys...e-world-521779

[fdr]

Originally Posted by MACH6

Often, the SIMPLEST explanation is the correct one….

A NEAR VERTICAL dive in a B737 can only be caused by SUSTAINED PILOT INPUT.

After the SILKAIR MI 185 disaster in 1997, several scenarios including RUDDER HARDOVER, JET UPSET, ENGINE FAILURE, STALLS, DEPRESSURISATION and SUSTAINED PILOT INPUT were simulated by the human factors group, which were part of the accident investigation team. (see final report).

SUSTAINED PILOT INPUT produced a nearly identical rate of descent and just under 3nm lateral distance travelled.

The other scenarios didn’t get anywhere near the same descent or distance travelled.Also, the aircraft exceeded the local speed of sound, causing the ‘boom’ sounds locals heard in the final stages of descent.

I hope the recorders can be recovered in a usable condition. But like the SilkAir accident, I’m sure they would have been disabled before the dive.

That is true for the MI185 case, the flight path was very well defined and it was difficult to replicate it. Other steep descents in the 30-50 degree range have occurred for other causes, the trim runaway being a low likelihood cause (except when someone does something pretty dumb with a system architecture unwittingly).

The data gives enough information to exclude most stalls as a cause, and a number of items can give a roll excursion that will drop the nose to below 30 degrees nose down in short order. The contenders for that sort of thing is a simple TS entry and disorientation, a slat element extension at cruise, a TR deployment, a revisit of the yaw damper/rudder reversal issue etc. Most of these are not likely but they get to the same point in time and space without being MI185 or EGYPT 990, or really odd events like Adam Air 574.

[fdr]

Originally Posted by Flocks

​​​​​
If it is not in China it doesn't count ? ...

Flash airline flight 604, malfunction lead to autopilot disconnected and pilot not controling their aircraft, that it is low altitude doesn't change anything, high altitude make it even more easier to loose control.

Adam air flight 574 ... High altitude lost of control after autopilot disconnectedhttps://en.m.wikipedia.org/wiki/Flash_Airlines_Flight_604

The descent rate varied during the fatal dive, with a maximum recorded value of 53,760 feet per minute,
From memory, I believe that the descent profile of the Adam air is quit similar of the one seems to be seen here.

I also remember a pilot suicide, with the pilot banking the plane high altitude and also same very fast descent from high FL to ground in few minutes, forgot which plane thought. Not saying it what happened there, but descent profile would also fit.

Flash 604 had some other controversial system possibilities raised that were discounted yet had occurred to the type previously, and in fact was photographed in a SAF B737 which got the crews attention. 574, the autopilot disconnection wasn't the basic problem, the turning off of reference systems for the APLT and the ADIs of the crew pretty much made that a most unfortunate event.

[waltair]

Originally Posted by Auxtank

I
Something went 'Twang' and it became unrecoverable (with the best will in the World being flown up front) but I have absolutely no idea how or why.

RIP

Maybe. Or maybe not. I teach people to fly these things. Done simulator with the China Eastern guys, this aircraft. Nice guys, I like them.

It would not surprise me at all if the report says they just kept doing “X“ until the plane crashed; never figured out what was going on. Human beings are fragile things. I would trust the machine over the man. I have seen people lock right up. And the other one just sits there. Totally possible. It is just how we are, we are fallible.

[FlightDetent]

484 TAS is closer to 440 CAS.

G-EZJK made it to 429 and already the AAIB bulletin noted the crew's actions on the yoke alone would not have stopped the descent.

[RatherBeFlying]

I have seen people lock right up. And the other one just sits there. Totally possible. It is just how we are, we are fallible.

Was right seat in a Viscount simulator (white on black AH) when the left seat got it upside down at 16,000 and just sat there with me screaming in his ear we were upside down until we hit the ground.

Would be a good simulator scenario to have in the curriculum, but don't prebrief the guy expected to take over.

[ATC Watcher]

@ Krautland :

ATC is an issue as they are military and speak to you in that tone.

That was a long time ago, they are civil now. The problem still is that the airspace around the civil routes is mostly military airspace and cannot be penetrated, even for weather.

[Doug Stark]

Originally Posted by diclemeg

Lets not get sanctimonious on our reporting and safety...after all it was the chinese who first grounded the Max.... and if not for them I would bet the FAA wouldn't have, ...

I have to disagree here. It was an ex NASA astronaut, the Minister of Transport for Canada that called the FAA to tell them that his experts had reviewed the data from both Max 8 crashes and had recommended (and accepted) to the PM that the Max be grounded in Canada. At the time, Trump viewed the Chinese grounding (1st group to do so) as 'political' and anti American. It was the final straw when Transport Canada ordered the grounding.

Check the Washington Post article dated 2019/03/13/

[Siu Mo To]

Originally Posted by A-3TWENTY

A lot of people had posted their opinions of what could have happened.

I flew in China for 10 years, being last flight in 2020. I'm not racist, just pragmatic.

The ATC there is crap. Not only the control itself, but also the attitude from ATC to the to pilots. Chinese pilots accept all kind of stupid requests from the ATC without a word. It is almost impossible a Chinese pilot refuse a stupid ATC instruction. Specially if the crew had a 2700 hrs Cpt.
It is well possible that they had an engine failure , request to descend and got a "stand by" as an answer. And they lost speed until the stall. It really would not surprise me at all.
I really think that China lasted a lot without a fatal accident. They had imminent accidents though out this years.
I remember foreign pilots had years of discussions in the cockpit because Chinese pilots flew at night with their radar off, and worst, with cockpit windows covered with newspapers to avoid radiation. Its happened until the day a wide body China Eastern flew into an isolated CB and lost 10000 ft. And so on. Many, but many stories. If you want to know more download flying upside down.pdf from the Internet.

So I really believe this accident had a partnership between ATC and crew. But.... as everything in China we will never know. BTW , probably the boxes were destroyed, but the communication between the plane and ATC wasn't revealed yet. Probably will never be.

Fortunately for all foreign pilots flying in China , it happened with a local crew.

My condolences to all families involved.

[QUOTE=A-3TWENTY;11204388]A lot of people had posted their opinions of what could have happened.


I flew in China the last 15 years and I still fly into China. I don't know if I should call it racist but I sense a lot of expats here seem to have the superiority complex.
Admittedly I have not operated with a mainland Chinese in the seat but I had a few in the jumpseat as "navigator" into non open airports. They seem reasonable when we had discussion about work.
I agree ATC is crap but it is not true to say the locals comply without a word. I can speak the language so I understand everything on the frequency. Often I heard pilots argued with ATC and some got very fiesty. And so you think a 2700 hrs captain from elsewhere will always speak up??? So there are no near mishaps in other parts of the world?? I do not agree with the punitive culture but it has been 10 years without a fatality. It is quite scary if you look at the safety stats of a large European/"Asian" airline but nobody talks about them even when they had a crash. When there is any incident Chinese related everybody jumped on it. When something happened and a local pilot saved the day nobody talks about it.
Having worked in a few companies with diverse workforce and also as a checker, I have seen people with substandard performance from every continet; so is good performance.

[swh]

CVR was found yesterday, the base of the unit had significate damage, the cylindrical memory unit which contains the data has the appearance of being in good condition was sent to Beijing last night. The NTSB has also been formally invited to participate in the investigation. https://www.reuters.com/article/chin...on-redirect=in


Source: Aviation Accident Investigation Center of Civil Aviation Administration

You Tube

[Auxtank]

Originally Posted by waltair

Maybe. Or maybe not. I teach people to fly these things. Done simulator with the China Eastern guys, this aircraft. Nice guys, I like them.

It would not surprise me at all if the report says they just kept doing “X“ until the plane crashed; never figured out what was going on. Human beings are fragile things. I would trust the machine over the man. I have seen people lock right up. And the other one just sits there. Totally possible. It is just how we are, we are fallible.

They are indeed. But this is when the training should kick in hard and achieve;

• Establish who has Controls. State it,
• Memory Items,
• Inputs to attempt to establish Straight And Level,
• QRH whilst the other is PIC.
• Work QRH Items for stated Outcomes.

I think they were doing more than just sitting there. I think they were very very busy. I think it's far easier to "Lose it and Lock Up"' in the sim (knowing it's only your job that's over and not your life) - a relatively consequence-free environment than when you're actually there in the air.

Sim work - it's hard to say - there are differences in the state of the mind - in some ways you're harder focused in the sim than real World and in other ways you're softer focused. What you cannot do in the sim is convince someone they're about to die if they get it wrong.
Knowing you're going to die will mean you will do ANYTHING you can to avoid that.
Looking at the somewhat spurious data so far - it looks very likely that the pilots were severely deprived of flight controls from on or soon after the initial upset occurred all the way to the impact on the ground. That would suggest a loss of one or more control surfaces.

[DaveReidUK]

Originally Posted by 43Inches

I also agree with a post that highlighted the two ADSB blips where there is an extended gap between responses of say 15 seconds, where both steep descents seem to originate, was there some sort of electrical fault or factor? From both ADSB cutouts the aircraft initiates a steep descent and lurches left, from what the plot shows.

A simpler, and more likely, explanation for ADS-B blips would be that there weren't any - the aircraft could well have continued to transmit normally, but for some reason those transmissions weren't picked up by FR24's crowd-sourced receivers, possibly due to an unusual aircraft attitude where the transponder antenna was blanked.

[Ngineer]

Unfortunately we are living in a COVID world where there are a lot of rusty people in the aviation industry. I have seen many maintenance errors as a result, and have been expecting to see many more. It would not surprise me if this was somehow related to an error. There are a lot of mechanisms in place to get Flt crew back up to standard after considerable time not flying, but in the maintenance field it is very different. And when workplaces are restructured to save costs during this mess, things are more likely to go wrong.

One example of how things can go wrong from a simple error. An aircraft is on the ground for an extended layover and all drains, static ports & pitot probes are covered up (etc, etc). All covers are removed at the return to service, however the pitot covers on the vertical stab are missed. It does not get picked up on the walk around. Aircraft goes flying and everything seems fine until the pilot disconnects the autopilot and tries to fly it manually with high airspeed. The elevator feel is subsequently compromised and the elevator controls are over sensitive.

In no way am I suggesting this as a cause, just an example of the unexpected. I have personally seen aircraft go flying with gear pins left in, drain covers still fitted, and maintenance paperwork not completed. The Aviation industry is different to what it was 2 years ago. Everyone needs to take an extra minute to double check what they, and others, have or have not done.

[nonsense]

Originally Posted by Doug Stark

I have to disagree here. It was an ex NASA astronaut, the Minister of Transport for Canada that called the FAA to tell them that his experts had reviewed the data from both Max 8 crashes and had recommended (and accepted) to the PM that the Max be grounded in Canada. At the time, Trump viewed the Chinese grounding (1st group to do so) as 'political' and anti American. It was the final straw when Transport Canada ordered the grounding.

Check the Washington Post article dated 2019/03/13/

https://www.washingtonpost.com/local...a61_story.html

[43Inches]

As many who have worked with or associated with Chinese aviation over the last 30 years would know the countries attitude to aviation is indeed changing to one of trying to maintain reasonable standards. This also involved change of attitudes towards the ex military pilots who were unsuited to airline style work and move to more western style management of training/checking processes for civil aviation. As with many other areas in China the industry is very punitive if you mess up, you don't get many chances if you stuff up, but that's not just China. Considering the challenging flying in China, with mountainous terrain and terrible weather and smog conditions they do a pretty good job, considering the amount of flying done these days. If you try and pin some cultural BS on their pilots it would just be from a prejudice mind.

[Ziaii]

Originally Posted by Ngineer

Unfortunately we are living in a COVID world where there are a lot of rusty people in the aviation industry. I have seen many maintenance errors as a result, and have been expecting to see many more. It would not surprise me if this was somehow related to an error. There are a lot of mechanisms in place to get Flt crew back up to standard after considerable time not flying, but in the maintenance field it is very different. And when workplaces are restructured to save costs during this mess, things are more likely to go wrong.

One example of how things can go wrong from a simple error. An aircraft is on the ground for an extended layover and all drains, static ports & pitot probes are covered up (etc, etc). All covers are removed at the return to service, however the pitot covers on the vertical stab are missed. It does not get picked up on the walk around. Aircraft goes flying and everything seems fine until the pilot disconnects the autopilot and tries to fly it manually with high airspeed. The elevator feel is subsequently compromised and the elevator controls are over sensitive.

In no way am I suggesting this as a cause, just an example of the unexpected. I have personally seen aircraft go flying with gear pins left in, drain covers still fitted, and maintenance paperwork not completed. The Aviation industry is different to what it was 2 years ago. Everyone needs to take an extra minute to double check what they, and others, have or have not done.

Thank you for bringing this up.
Yes, investigation should include records of maintenance performed in this CoViD era.
And check all possible tasks that may have been missed (or exceeded if time-controlled).

[Vhammer]

Fortunately the throttles and flight controls are not interlinked.
With over 10K hours on the 737 including the 800 and Max, and some training in accident investigation, I'd like to offer a few observations.
First off, I don't believe it is possible to reach the ground in two minutes without the throttles pushed up. No one keeps power in, in a dive. Its instinctive for anyone that's been flying for any period of time to reduce power to idle.
Now with power at idle I don't think even vertical you can descend 29K feet in two minutes.
Now to get vertical, you would have to have a condition where not only are the flight controls unresponsive but they have had to go into a full nose down position by themselves, and be resisting input to reduce the angle of descent, which without some kind of assistance would not normally occur on their own.
OR you would have have to a failure of the flight control system as well.
So we are talking two separate events, by systems not related, except by the person flying.
I could be grossly mistaken, but I don't believe you will find much data coming out of China that isn't manufactured. The airplane has been in service 7 years, so bugs have been worked out. This leaves one of several possibilities.
Crew action, maintenance or some external factor.