China Eastern 737-800 MU5735 accident March 2022

[AAKEE]

That has certainly been true - up to a point - for the dozens of accidents/incidents that have featured in these columns over the years and where FDR traces have subsequently been published in the investigation report (including the two Max accidents).

But there is an important caveat: ADS-B data (as transmitted by the aircraft) and an FR24 download (however granular) are not the same thing. The latter will be subject to asynchronicity, hysteresis and latency - though many (but not all) of those issues can be mitigated with some work and patience.

So, while I have no sympathy for the knee-jerk "ADS-B is rubbish" view sometimes expressed in these columns, nor do I agree with the "ADS-B is gospel" view when applied to FR24 data. Using the granular data from this accident in a software that allows for a 3D view of the data points in position and altitude we can se things that we can not when just looking at the table.

This aircraft started the departure from stable flight with a roll to the left, and this roll got more and more like a barrel roll from about inverted. Probably due to a about 1G postitive load during the roll.
The aircraft seem to have performed at least one complete roll, completed about when the aircraft briefly gained altitude again. There is a possibility that the aircraft continued to roll after the first barrel roll.

Sriwijaya 182 had a A/T failure that put #1 Engine to idle. It made a similar left barrel roll.

Maybe something similar A/T or engine failure or a rudder hardover( I know they aren't supposed to happen these days but…)

[Sailvi767]

I have had a catastrophic engine failure in cruise flight in a 767-300 ER. Instant loss of all thrust. In cruise flight it’s actually a very benign maneuver. You would have to be dead asleep to let it rollover. It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds. Rudder hardcovers normally are a problem at low speeds where full throw is available.

[EDML]

It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds. Rudder hardcovers normally are a problem at low speeds where full throw is available.

Correct. The accidents after the rudder hard over with the 737 happened at rather low speed during the approach. At higher speeds there is enough aileron authority to overcome the rolling moment caused by the rudder. One of the "fixes" was to apply higher speeds for flaps 1-10 to avoid the speed envelope where a hard over could not be counteracted by the ailerons (called crossover speed).

There were also some incidents with the rudder PCU that happened in cruise flight. They were recoverable.

[Magplug]

It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds.

That's very true... Under normal conditions and presuming the RTL performs as expected. Look at the the 747 lower rudder valves malfunctions that have occurred and you will see that is not always the case. The rudder may travel beyond the RTL limits resulting in LOC.

[Feathered]

The trim system in the 737 is very obvious if not annoying when running. That includes when the autopilot trims. If in fact they ignored the spinning trim wheels and noise as soon as the autopilot moved the elevator to counter the incorrect trim input the trim brake would engage and stop the runaway.

The 737's trim does make a very noticeable clatter when running. But if there is also cacophony of alerts, plus a stick shaker simultaneously making noises and distracting the pilots from listening to trim wheels, I'm not sure we can count on trim system noise to provide sufficient a human factors warning when things are off nominal. The trim brake is another issue.... So many unknowns at this time. Anxiously awaiting for actionable FDR data....

[Mr Optimistic]

[pax] I think any proposed cause has to account for the timing of the event ie at or about start of descent. A random occurrence, eg collision or mechanical failure could otherwise have occurred with equal probability at any earlier time in the cruise. More likely to be associated with a circumstance specific to that phase of flight surely.

[Stick Flying]

[pax] I think any proposed cause has to account for the timing of the event ie at or about start of descent. A random occurrence, eg collision or mechanical failure could otherwise have occurred with equal probability at any earlier time in the cruise. More likely to be associated with a circumstance specific to that phase of flight surely.

I don't agree. That is making an assumption it was changing from cruise to descent at that point and something in that process went catastrophically. It could be a multitude of reasons this flight went horribly wrong. Probabilities are fortunately something the investigation team will ignore unless it backs up FACT. If the recorders are readable, they will give a far better insight than any assumptions can.

[N600JJ]

Could this be similar to Southwest B737-700 flight 1380 in 2018 whose incident report can be found at https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93897/pdf? https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1380

Uncontained engine failure with a sudden left roll of a 41° bank angle leading to decompression of the aircraft, emergency descent and damage to, amongst other parts of the aircraft, wing tip and horizontal stabilizer?

[SteinarN]

Could this be similar to Southwest B737-700 flight 1380 in 2016 whose incident report can be found at https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93897/pdf?

Uncontained engine failure with a sudden left roll of a 41° bank angle leading to decompression of the aircraft, emergency descent and damage to, amongst other parts of the aircraft, wing tip and horizontal stabilizer?

I made an argument the left roll (there can be no doubt that a left roll was the start of the flight path deviation) could most likely be caused by either an uncommanded rudder movement or an engine malfunction causing the left engine to lose thrust and taking the crew by surprice. ie crew not taking action before AP disconnect in an out of trim state. Alternatively an uncontained engine failure also damaging rudder cables/controls and/or wing surfaces.
However that post have since been deleted by the mods.

I was surpriced by the number of cracked fan blades found acording the the report you are linking. That another fan blade could depart an 737NG engine can hardly come as a surprise, however I do not say with any certainty that an engine malfunction did actually happen in this accident, only that such a failure is one of the more likely reasons for this accident.

[A0283]

Looking at posts 250 and 255 and wholly speculatively, how could a reduction in thrust at top of descent instead have activated a thrust reverser ? Did somebody say they have only found one engine ? Post 214 and nobody has rushed it to say it's wrong.

Dave it means that on the photo and video material that I have seen, there was only one engine visible (suprisingly - with the fan side up) next to a pool of water that they called the 'first pond', the circumference appeared quite intact, but the engine somewhat flattened. I did not observe the removal of that engine from the mud. And did not see the other engine. Indeed nobody commented on this then or later. So we dont know if it is the left or right hand engine that was found.

I did observe for example the removal of the outerwing/winglet from the deep mud, and the removal of a top of one big MLG fragment including trunnions. And observed the handling of the FDR 'can' just after it was found. The CVR can was a Honeywell.

The investigation reports things like 24,000 earlier and yesterday 33,777 pieces found in their press conferences, but does not make statements on the four corners or main components that have been found, apart from the CVR and FDR. They appear to have established a pretty thorough process chain for filtering, handling and identifying parts, so that information should be available by now. That they dont make that public may or may not be surprising.

[VFR Only Please]

(...) On the one hand the Chinese are being uncharacteristically open with their press conferences but may still be guarded in their admissions of the possibility of a mid-air collision with an errant mil-jet. Everything outside of airways in China is mil-controlled. Consequently getting co-ordination for wx avoidance is downright impossible. Equally an errant military jet may have infringed civil airspace resulting in a mid-air (...)

Am guessing at least one non-Chinese party (Boeing) will take part in this investigation.
A collision may be unlikely, but suppose that were the case. The Chinese would be reluctant, putting it mildly, to admit this.
Interesting dynamics in multinational investigation team, a bit like the WHO looking into the lab-leak hypothesis.

[DaveReidUK]

Am guessing at least one non-Chinese party (Boeing) will take part in this investigation.

No guesswork required. It has already been announced that the NTSB will participate in the investigation, supported by Boeing and CFM.

[B2N2]

The future of Boeing is at stake let’s not forget that.
They’ve barely recovered from the Max debacle and a potential fleet wide problem with the -800 series could very well be the end of it.

[BuzzBox]

The Chinese government and media outlets are reporting that all 132 victims have been 'identified' through DNA testing, cross-matched with samples taken from their relatives. That seems quite a tall order, given the accident only occurred a week ago and the difficulty of recovering remains from the crash site.

http://english.www.gov.cn/news/topnews/202203/28/content_WS6241a89ac6d02e53353285ed.html

[dr dre]

The future of Boeing is at stake let’s not forget that.
They’ve barely recovered from the Max debacle and a potential fleet wide problem with the -800 series could very well be the end of it.

Given the airframe has been around for 24 years it would be very rare if an endemic problem that causes catastrophic uncontrollable states has been lying dormant and undiscovered that whole time.

The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.

[B2N2]

Given the airframe has been around for 24 years it would be very rare if an endemic problem that causes catastrophic uncontrollable states has been lying dormant and undiscovered that whole time.

The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.

Except this airframe wasn’t 24 years old.

Manufacturer Serial Number (MSN) 41474
Line Number 5453
Aircraft Type; Boeing 737-89P(WL)

First Flight 5 Jun 2015
Age 6.8 Years
Production Site Renton (RNT)

Changes in production methods, materials, quality control etc etc etc.
Boeing is certainly not in the clear.
The Max is still not re-certified for Commercial operations in China and they may delay even further.

[BoeingDriver99]

If anyone thinks the Max will ever fly in China again they are dreaming.

[ywagd]

Something the newer 737 ng have in common with 737 MAX
All 737 MAX and most 737 ng manufactured 2014 or later (I'm not sure about date) are equipped with a new model of the motor and motor driver that is used for electric trim.

There could be a difference in how the newer motor and motor driver is able to restore normal trim after a runaway trim. Compared with older motors.

The new trim motor and driver that came around 2014 is from Eaton and is called Model 6355C. Among what is new is:
– Brushless three phase motor
– Dual current limit (torque) control circuits

I have not been able to find any information about when the current limit/torque limit kicks in. The strong force required to recover from e.g. a runaway trim if the mistrim is compensated for by elevator, have been shown that it can be impossible to fix with the cockpit wheels. Even if both pilots try to, manually. Unless a maneuver like the "roller coaster maneuver" is used.

There is not so much information about Eaton Stabilizer Trim Motor 6355C available, but here is some.

Search for:
Eaton Stabilizer Trim Motor 6355C

I'm not allowed to post links.

/ywagd

[EDLB]

That can be everyone's guess. But since the FDR and CVR data are most likely available in a few days, there is no need to speculate. I am sure the reason will come out regardless what face saving by whatever party might be involved. FDR and CVR data can be sent by email so no need for NTSB or Boeing people on site waiting for any Covid clearance.
China has grounded a lot -800 so they have some interest to figure this out.

[CRayner]

The Chinese government and media outlets are reporting that all 132 victims have been 'identified' through DNA testing, cross-matched with samples taken from their relatives. That seems quite a tall order, given the accident only occurred a week ago and the difficulty of recovering remains from the crash site.

All 132 victims of China's plane crash identified (http://english.www.gov.cn/news/topnews/202203/28/content_WS6241a89ac6d02e53353285ed.html)
PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

[BuzzBox]

PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

Sure, but given the aircraft was pulverised by the high-speed impact, I'm surprised they've been able to find and identify DNA material from ALL of the occupants in such a short space of time.

[ywagd]

My guess is that the hundreds of workers that have been working for days to collect everything, including parts and fragments from the plane, and body parts, soon had collected many thousands of fractions from both the plane and from victims. When 132 different DNA profiles had been found the next step was to identify the individuals. Often through DNA from relatives.

[diclemeg]

PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

I read that headline and am in disbelief.... to isolate 132 individual DNA in that wreckage...especially the souls in the back of the plane who probably ended up far down the hole. I can't fathom how they could do this.

[flash8]

PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.Also given the high surveillance in China, probably all were scanned on a/c entry by various biometric devices and they knew everything irrespective of the manifest. Likely have the DNA on record of all the passengers as well. Probably the most intrusive place in the world so not surprising I agree.

[Lake1952]

I read that headline and am in disbelief.... to isolate 132 individual DNA in that wreckage...especially the souls in the back of the plane who probably ended up far down the hole. I can't fathom how they could do this.

Not to get too morbidly graphic, but do you think the souls in the front of the plane fared better than the ones in the back?

[diclemeg]

Not to get too morbidly graphic, but do you think the souls in the front of the plane fared better than the ones in the back?

The point was those in back of plane would end up far into hole, and harder to access/isolate their DNA, vs those in the front, as the impact would scatter on the surface, this notion further makes me doubt their claim of identifying 132 distinct DNA.

[A0283]

Sure, but given the aircraft was pulverised by the high-speed impact, I'm surprised they've been able to find and identify DNA material from ALL of the occupants in such a short space of time.

Based on what I have seen the aircraft is fragmented and the fragments are bent and torn with no sign of fire on them (there was a fire in the trees above the crash site, so apparently some fuel has been thrown forward and up).The largest pieces are parts (top and or bottom panel fragments) of the wing(s) which are a few meters long and say half to one meter wide. One of the engines (bare engine only, no cowlings) was easily identifiable, the other may have been found too as there are two stacks of engine components. Another parts seems to be a part of the THS and another part of the wing. Both are a few meters long, but can be carried by say 6-7 guys. Until now I have only seen one piece of wiring of about 20cm long. No instruments shown at all, but reported that manuals from the cockpit had been recovered. Next to that many white bins with fragments.

In one of the early press conferences they mentioned that all the passengers were Chinese nationals. So there was no need to go into the more lengthy process of asking foreigners to come forward. Based on this you might say that there is a difference in identification time between an all nationals flight and a flight with a mix of (inter-)national passengers.
China makes extensive use of facial recognition, a BBC video showed they could find a reporter in Shanghai or similar within 7 minutes, so they might have used that to take a look at images at the airport to confirm who actually entered the aircraft. On the first day they mentioned one more passenger than thereafter.
Many countries have identification processes in place these days to enable quick identification. The area was hot (30C) and very humid (heavy rain for days), so they had to work fast.

During the weekend the investigation and authorities declared all PoB deceased. From that point on they start making more use of heavy machinery and are building and widening roads to support the recovery effort. The continuous rain has made this a big effort.

[wrench1]

I can't fathom how they could do this.
FWIW: Given how they used to identify people in this scenario prior to DNA, it would definitely seem plausible with todays DNA/computer technology to ID their remains much quicker and probably with better accuracy. The human body doesn't simply vaporize on impact.

[diclemeg]

FWIW: Given how they used to identify people in this scenario prior to DNA, it would definitely seem plausible with todays DNA/computer technology to ID their remains much quicker and probably with better accuracy. The human body doesn't simply vaporize on impact.

No, it doesn't vaporize, but it is organic and burns and is consumed. I simply do not believe they identified all 132, and no less before they found the second black box. Maybe I am wrong, and maybe they had a big group focused on just DNA sampling. I saw the images of the fires and the heavy rains, and such and just don't believe the claim.

[41queenspark]

At 1.08 in to the video, notice the blank panel for the window aperture on the starboard side last row of the window belt. There is some material trapped by the window blank and the fuselage skin. Has this material [possibly part of a seal] failed in the air, not impact damage. See Rescuers recover transmitter installed near second black box. CNGT 26TH march

[Europa01]

ywagd
If you go to the Eaton.com website and search on B737 stabilizer trim upgrade there is a sales type technical description of 6355C trim motor. Not sure what your getting at in the context of this event though.

[DaveReidUK]

Rescuers recover transmitter installed near second black box. CNGT 26TH march

CGTN actually reported on 26th March that the recorder itself had been found, not just the ULB.

Video shows where second black box from MU5735 was discovered - CGTN (https://news.cgtn.com/news/2022-03-27/Video-shows-where-second-black-box-from-MU5735-was-discovered-18JP5O44m08/index.html)

[ywagd]

ywagd
If you go to the Eaton.com website and search on B737 stabilizer trim upgrade there is a sales type technical description of 6355C trim motor. Not sure what your getting at in the context of this event though.

Probably it is not of significant here.

But, if we in a few weeks from now learn that this accident started with a runaway nose down trim where the plane initially was kept from diving with elevator, then this could be of significance.

I think other scenarios are more likely, but when we get FDR data we will know more.

/ywagd

[Sailvi767]

For the above to happen you would need a series of events that is hard to imagine. First the trim motor would need to begin a runaway. As soon as that happened the autopilot or pilot flying would counter that with elevator movement activating the trim brake. If the trim brake failed which would be a completely different failure from the initial runaway the pilots would need to not notice the autopilot disconnect warning, nose pitching down, change in G forces, spinning trim wheels. If any off the above was noticed the pilots would simply hit the trim disconnect switches. They would also intuitively trim counter to the runaway. Either action should stop the runaway. They could then continue the flight using manual trim. The trim brake is a robust system we checked on the first flight of the day so it’s tested often.

[AAKEE]

I made an argument the left roll (there can be no doubt that a left roll was the start of the flight path deviation) could most likely be caused by either an uncommanded rudder movement or an engine malfunction causing the left engine to lose thrust and taking the crew by surprice. ie crew not taking action before AP disconnect in an out of trim state. Alternatively an uncontained engine failure also damaging rudder cables/controls and/or wing surfaces.



Yes, the left roll is quite clear.

I was not thinking ”rudder hardover” as necessarily not controllable failure.
A uncommanded rudder movement ( or A/T failure like Sriwijaya) and a A/P disconnection and spatial desorientation.

Sriwijaya 182 seems to have rolled left without noticing it, at least initially. Might be the same this time?
An uncontained engine failure could possibly damage the aircraft and cause something like this, but my guess is that if you get a uncontained engine failure you will wake up and get on your toes quite quickly…

To posters with the view that it can not be a rudder hardover/uncommanded movement or Eng failure: What would cause the aircraft to perform a left roll + second half of a barrel roll?
Any ideas?

[VFR Only Please]

Given the airframe has been around for 24 years it would be very rare if an endemic problem that causes catastrophic uncontrollable states has been lying dormant and undiscovered that whole time.

The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.

"Dormant" may be the key word. Certainly some ex-Boeing people blew the whistle some years ago on manufacturing shortcuts that could enhance fatigue & erosion. Which would take time. Meanwhile, landing mishaps have caused the NG fuselage to break lethally into sections that some experts say represents excessive damage for the forces involved.
How "endemic" it was would depend on whether Boeing cleaned up its act when people started blowing whistles.
If so, it would still be worth following the fate of that batch of aircraft.

[Flyhighfirst]

Also given the high surveillance in China, probably all were scanned on a/c entry by various biometric devices and they knew everything irrespective of the manifest. Likely have the DNA on record of all the passengers as well. Probably the most intrusive place in the world so not surprising I agree.


Most laughable paragraph I have read in awhile. Get out of the house and stop reading spy novels. No country has DNA samples of its entire population. Especially a country so populous as China. There are no “biometric devices “ scanning you on aircraft entry either. There maybe facial recognition in the terminal but that is about it. And even then it isn’t gathering data about you. But scanning you against a database.

[hijack]

Runaway trim... doesnt it says on the memory items not to reengage the autopilot? Could this be the case when it level off and reengaged the autopilot leading to another freefall?

[ChicoG]

No guesswork required. It has already been announced that the NTSB will participate in the investigation, supported by Boeing and CFM.

But not yet because the Chinese have only just issued visas (surprise surprise). And they still have the quarantine card to play if they wish to be obstructive for a little while longer.

[4runner]

Most laughable paragraph I have read in awhile. Get out of the house and stop reading spy novels. No country has DNA samples of its entire population. Especially a country so populous as China. There are no “biometric devices “ scanning you on aircraft entry either. There maybe facial recognition in the terminal but that is about it. And even then it isn’t gathering data about you. But scanning you against a database.

you are naive or misinformed about the Peoples republic. Not only do they gather their own peoples dna, they are purchasing western databases as well.

[Recc]

you are naive or misinformed about the Peoples republic. Not only do they gather their own peoples dna, they are purchasing western databases as well.

Maybe not the place to have this discussion as it is completely irrelevant to the topic.
Genotyping (even 10s of thousands) of recovered tissue samples on a forensic STR kit is trivially easy. Genotyping 300 samples from relatives is trivially easy. Statistical matching of STR profiles for identification is trivially easy. Whether you have a pre-existing database would have next to no influence on the technical process. As someone else pointed out above, the difficult bit is finding and collecting the tissue samples.

[Gary Brown]

Maybe not the place to have this discussion as it is completely irrelevant to the topic.
Genotyping (even 10s of thousands) of recovered tissue samples on a forensic STR kit is trivially easy. Genotyping 300 samples from relatives is trivially easy. Statistical matching of STR profiles for identification is trivially easy. Whether you have a pre-existing database would have next to no influence on the technical process. As someone else pointed out above, the difficult bit is finding and collecting the tissue samples.

There is perhaps a slight relevance - one way of reading the official Chinese government statement on the DNA identification is that none of the expected passengers and crew were (last minute?) missing; and that no DNA other than that expected was found. Somebody on the investigating teams will have been tasked with checking those two possibilities out.....

[A0283]

Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.

Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."

[Gary Brown]

Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.

Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."

I can't put my finger on the official Final Report either, but there's a decent Wiki ( https://en.wikipedia.org/wiki/China_Southern_Airlines_Flight_3943 ) and a useful ASN Summary ( https://aviation-safety.net/database/record.php?id=19921124-0 ).

[SteinarN]

I can't put my finger on the official Final Report either, but there's a decent Wiki ( https://en.wikipedia.org/wiki/China_Southern_Airlines_Flight_3943 ) and a useful ASN Summary ( https://aviation-safety.net/database/record.php?id=19921124-0 ).
I think something like this could easily have been the triggering cause for the crash. Except no clutch slippage but some other reason for asymetric thrust. Or at least one of several more likely causes.

[DaveReidUK]

Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.

Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."

There's a fairly comprehensive summary of the investigation report here (https://inf.news/en/aviation/583dc2f0075addaf9b1816845ac4b923.html).

[diclemeg]

All 737-800s at MU are grounded
My hunch is a runaway trim.
Even if it was, it still becomes pilot error, and not a reason to ground planes..Has occurred too many times the pilots don't notice the spinning wheel with the alerts going off..

[epc]

I believe the correct info was: Captain 6709 hrs, F/O 556 hrs, check/training captain 31769 hrs

That is incorrect. The Chinese language sources are clear on the following:

The Captain had 6k hours.

The first First Officer had 32k hours.

The 2nd First Officer had ~500 hours.

The reason for this seemingly odd crew composition was also clearly stated in the Chinese language reporting:

The 32k-hour pilot was one of the most experienced civil aviation pilot in China. He was one of the first Chinese pilots who started flight training as a civilian, rather than military. He started his career just as the Chinese civil aviation was taking off in the early 80s. He was scheduled to retire this year. The reason he had so many hours but yet was not flying as Captain was the airline had retired the 767 on which he was rated as Captain, so he was now being converted to 737.

The young 2nd First Officer was in the third seat. He was assigned to this flight in order to "gain experience." That's all the Chinese language reporting said about this pilot. No further explanation was given how sitting in the third seat could help gain experience.

The Captain was hired as a 737 captain in January, 2018. Nothing remarkable was reported about him.

[EDLB]

CAAC promises a preliminary report within 30 days. https://www.scmp.com/news/china/politics/article/3172492/china-promises-public-report-fatal-air-crash-probe-within-30?utm_source=copy_link&utm_medium=share_widget&utm_campaign=3172492

[Matt48]

Probably the worst thing you could have is a cockpit full of pilots.

[SteinarN]

Probably the worst thing you could have is a cockpit full of pilots.

Well, I think it is generally accepted that the third pilot on the Qantas A380 uncontained engine incident was extremely usefull in securing a positive outcome and bringing the aircraft safely down on a runway.

The same can be said about the third pilot in the cockpit on the first Lion Air Max incident with the MCAS runaway where also that aircraft was brought to a safe landing. Acording to reports it was input from the third pilot that possibly saved that flight.
The two other known MCAS malfunctions had only two pilots in the cockpit, and both crashed catastrophically.

[MATELO]

Probably the worst thing you could have is a cockpit full of pilots.

Al Haynes would have staunchly disagreed with you on that one.

[Rhys S. Negative]

The reason he had so many hours but yet was not flying as Captain was the airline had retired the 767 on which he was rated as Captain, so he was now being converted to 737.

Interesting. CES only operated three B767s, and they left the fleet more than a decade ago (2011).

[Sailvi767]

It’s possible he went to the 737 after the retirement of the 767 and was still a check Captain giving a check ride. If so nothing to see here. That would not however be the normal career path.

[FUMR]

I'm not a pilot.

If it was a check ride, I wonder if the check captain perhaps simulated some sort of emergency which was incorrectly handled and got out of control? I am well aware that it's not SOP to practise simulated emergencies with a plane load of passengers, however.......
Just a thought to add to the many others.

[FlightDetent]

There are more options, e.g. the LHS PIC needing an instructor for reasons of recency.

Yet the Chinese official media are typically correct about what they are trying to say. F/O sounds like an F/O, especially if announced on the CAAC News website (did not check myself). Link click here. (http://www.caacnews.com.cn/)

Some is easier to imagine, such as a long-time LH instructor having enough of surfing the timezones and coming back to 737 i.s.o. 777/787, some harder. How does 31k hours fit within one lifetime?

[Winemaker]

There are more options, e.g. the LHS PIC needing an instructor for reasons of recency.

Yet the Chinese official media are typically correct about what they are trying to say. F/O sounds like an F/O, especially if announced on the CAAC News website (did not check myself). Link click here. (http://www.caacnews.com.cn/)

Some is easier to imagine, such as a long-time LH instructor having enough of surfing the timezones and coming back to 737 i.s.o. 777/787, some harder. How does 31k hours fit within one lifetime?
I'm curious about this number also. Over 20 years that's flying about 30 hours/week.......every week.

[epi]

I'm curious about this number also. Over 20 years that's flying about 30 hours/week.......every week.
Starting from early 80's, that's almost 40 years. So maybe 15-20 hrs/week

[ehwatezedoing]

I'm curious about this number also. Over 20 years that's flying about 30 hours/week.......every week.
It says somewhere above that he was about to retire, so how about 40 years!? :hmm:

[FlightDetent]

From the deleted files:

Joined Yunnan Airilnes 1985
Received 737 at Seattle 1988
Become captain 1991
Flew the 767 for more than 10 years

A post above claims CEAir retired 767 in 2011. That's at least 4 big trainings (5 months around) plus the last 2 years of COVID.

35 years gives 888 per annum without missing one. Tough love (or?).

[Sailvi767]

I'm not a pilot.

If it was a check ride, I wonder if the check captain perhaps simulated some sort of emergency which was incorrectly handled and got out of control? I am well aware that it's not SOP to practise simulated emergencies with a plane load of passengers, however.......
Just a thought to add to the many others.

I can’t conceive of that happening especially in China where every flight aspect is monitored. Line checks are to observe normal operations. Emergencies are practiced in the simulator.

[silverelise]

It’s possible he went to the 737 after the retirement of the 767 and was still a check Captain giving a check ride. If so nothing to see here. That would not however be the normal career path.

I watched a "Lei's Real Talk" video in which she says she has information that the "award winning" 30k+ hours 767 captain "with unparalleled safety record" moved to 737s when the 767 fleet was retired (in 2011), then was involved in an incident last year where he flew "out of a terrain warning zone at an airport" which the company recorded as a "serious safety mistake" and demoted him from Captain to First Officer following a simulator test.

[epc]

Interesting. CES only operated three B767s, and they left the fleet more than a decade ago (2011).

You are right. When I read the original Chinese stories, I didn't check the timeline. Now that you mentioned it, I went back and read that he had already started flying 737 many years ago. It's curious he wasn't promoted to captain.

There's rumor that he was promoted, but was then demoted back to FO after an incident. But it's a rumor on social media only.

[PJ2]

I haven't flown the B737 but have flown & taught on the A320 & other Airbussi (as well as Lockheeds, McD's & Boeings); I am familiar with the Sriwijaya accident & earlier pitch-down accidents resulting from loss of crew situational awareness where it concerns a loss of engine thrust.

A loss of thrust at cruise power would result in some yaw but not an uncontrollable yaw and certainly good control over any roll, and if engine thrust had been set for the descent, (idle thrust) and the aircraft was descending normally, (about 2000fpm or so), there would essentially be no yaw at all.

I like what fdr has had to say on the subject and I think it is wise to consider this accident from what he observes as possible. I take seriously what he says about the few causes of significant pitch-downs occurring without the crew's roll input. As he says and provides examples for, we should look elsewhere and, unless seriously mishandled, not engine failure for the source of roll & pitch-down. Whether this is similar to the China Airlines B747-SP (http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/ChinaAir/AAR8603.html) incident or not remains to be seen.

[sycamore]

Would a real 737 pilot care to comment on the likelihood of a thrust reverser opening in flight...?

[FlightDetent]

Would a real 737 pilot care to comment on the likelihood of a thrust reverser opening in flight...?We've had a real Boeing propulsion engineer comment on that. Who has seen the investigation of Lauda 767 from the inside.

Nope, unimaginable (my wording).

[tdracer]

FlightDetent, you called? :)
Actually, I don't recall commenting on the TR deployment on this thread.
Would a real 737 pilot care to comment on the likelihood of a thrust reverser opening in flight...?
After Lauda, Boeing added a 'third lock' to the reverser system on all aircraft (I believe the 737 NG uses a 'sync lock' that locks the device that synchronizes the movement of the T/R actuators). It would require three independent failures - of which two are non-dispatchable faults that should result in the reverser being locked out prior to flight. There have been issues in the past with improper lockout procedures on the 737 NG (basically it was possible to insert the lockout pin without it actually engaging) - memory says Boeing issued a fix for that (which was promptly AD'ed by the feds) maybe 15 years ago.
The probability of all three faults allowing a reverser to deploy in flight is something like 10-13/hr (i.e. one in 10 trillion flight hours), and even when dispatched with a latent failure of one the locks is something like 10-8/hr. So possible, but very, very unlikely.

All that being said, the reported flight profile of this accident does have a striking resemblance to what happened to Lauda.
At the risk of being called a racist again, I'd really like to know what was done to that aircraft as it sat on the ground for the two days prior to event flight.

[flyingchanges]

FlightDetent, you called? :)

The probability of all three faults allowing a reverser to deploy in flight is something like 10-13/hr (i.e. one in 10 trillion flight hours).




Just to put that into perspective, it is roughly 1 billion flight hours for every 737 ever made...

[Nuasea]

---Zero---
it’s a few years ago now since I trained pilots on the BAe 146 for China North West. Maybe things have changed but the F/O’s easily adapted to EFIS while the captains, ex Russian aircraft, struggled.

As the F/O’s pointed out, they were condemned to be just radio operators for the next several years before being offered a command.

There was nothing I could do to change the system. Maybe things have changed.

[megan]

PJ2 quote - A loss of thrust at cruise power would result in some yaw but not an uncontrollable yaw and certainly good control over any rollFrom the Southwest 1380 report where the engine failed climbing through FL320FDR data showed that the airplane’s uncommanded roll to the left reached a maximum of 41.3° at 1103:44. The first officer, as the pilot flying, began to roll the airplane back to wings level; about 6 seconds later, the airplane’s left roll was 5.1°, at which point the roll attitude was generally back under the pilots’ controlIn the following video a 777 Captain describes an engine failure in a 777, aircraft rolled to 45° and roll control was so difficult he very briefly considered taking the aircraft through the remaining 315° in a barrel roll, beginning at 5:45,

https://www.youtube.com/watch?v=J7_lzeY23dI

As SLF when it comes to jets the lesson I take away is that an engine failure may not be that benign.

[PJ2]

From the Southwest 1380 report where the engine failed climbing through FL320...As SLF when it comes to jets the lesson I take away is that an engine failure may not be that benign.The SW B737 engines would have been in climb thrust, not cruise thrust. Thrust produced by the engines for the climb is greater than that required in cruise so loss of a higher level of thrust would certainly be noticeable to the crew and the airplane would respond more firmly to the assymetric thrust.

The report paragraph you quote states that the First Officer had the aircraft under control, returning the bank angle from 41° to 5° within 6 seconds. That was the point in my post - engine failure will cause yaw but in all ordinary, (uncomplicated) circumstances, is controllable whether on takeoff, climb, cruise, descent and approach. The event is practised in the simulator every six months or so.

The other event occurred on a B777 and with loss of thrust from the right engine, the aircraft responded to the yawing moment, (nose turning to the right in this case) and began to roll. The bank angle reached 45°. Control of the aircraft was handed to the captain, (normal decision depending upon circumstances in the moment), and the bank angle was reduced. The Incident Report does mention the challenge of control but the aircraft remained wings level.

There is no observable reason to compare either of the above events with the China Eastern accident. But, while rare, matters can get very complicated very, very quickly.

When the flight data becomes available, we will know better. Aviation has a way of making any one of us eat our own words, once in a while. I have dined at its table a number of times... :rolleyes:

[WYOMINGPILOT]

The Chinese system is very different than the West. The high hour FO was likely a check airman in the right seat and doing either line training or an annual line check. The young observer FO is just in the jump seat to gain experience. A very common practice in Chinese airlines.

Typically you fly with 3 pilots so the young FOs can gain experience during their ab- initio training style program. They have 500 hours just of observation flights before they are fully checked and have about 1000 hours actual right seat time before they are signed off to operate as a solo FO.

Many times I flew as an Expat Captain on a 4 day trip and the two FOs would trade off each day of the 4 day rotation. You may think 31,000 hours is high and it it certainly is but most Chinese pilots are flying about 900 hours per year except the past 2 years of Covid, that is the norm. Pay is also based on flight time so they also want to fly that for max pay. The more senior pilots do get the more efficient trips also so less work days to get that 900.

The junior pilots fly 14 hour duty days and 4 sectors but only get 4 hours of actual flight time and pay credit. It was said the right seat may have been downgraded and that is also very possible if he had a serious under their standards mistake like a terrain warning GPWS callout. It’s a massive punishment culture and everyone gets punished for one guys mistake. They strangle many chickens to scare the monkey in China.

I flew 8 years in China and can say it was both the best of times and hardest of times. Unless you’ve experienced extreme scrutiny and evaluation of your every input you won’t know what I’m talking about but some of the flying was actually very enjoyable and some great Copilots I flew with, much better pilots than myself down to 500 feet, you just had to pay attention or they could get you into trouble easily with a hard landing 1.7 G or above.

The simulator training is by far the most intense you’ll ever get in the industry and runaway trim, rudder hardcover and jammed elevators and stabilizers are routinely practiced in the sim but no actual emergencies can be practiced in the aircraft.

[Sailvi767]

The SW B737 engines would have been in climb thrust, not cruise thrust. Thrust produced by the engines for the climb is greater than that required in cruise so loss of a higher level of thrust would certainly be noticeable to the crew and the airplane would respond more firmly to the assymetric thrust.

The report paragraph you quote states that the First Officer had the aircraft under control, returning the bank angle from 41° to 5° within 6 seconds. That was the point in my post - engine failure will cause yaw but in all ordinary, (uncomplicated) circumstances, is controllable whether on takeoff, climb, cruise, descent and approach. The event is practised in the simulator every six months or so.

The other event occurred on a B777 and with loss of thrust from the right engine, the aircraft responded to the yawing moment, (nose turning to the right in this case) and began to roll. The bank angle reached 45°. Control of the aircraft was handed to the captain, (normal decision depending upon circumstances in the moment), and the bank angle was reduced. The Incident Report does mention the challenge of control but the aircraft remained wings level.

There is no observable reason to compare either of the above events with the China Eastern accident. But, while rare, matters can get very complicated very, very quickly.

When the flight data becomes available, we will know better. Aviation has a way of making any one of us eat our own words, once in a while. I have dined at its table a number of times... :rolleyes:

The Southwest aircraft yawed and rolled because the engine suffered a uncontained catastrophic failure causing extensive cowling damage that dramatically increased airframe drag. Even given it was at a high thrust level and the aerodynamic drag it was easily controllable. That’s a very different scenario than what we know about China Eastern.

[megan]

Quote PJ2 - Thrust produced by the engines for the climb is greater than that required in cruise so loss of a higher level of thrust would certainly be noticeable to the crew and the airplane would respond more firmly to the assymetric thrustG'day PJ, The Captain described the roll upon failure as a "snap roll" and thought that they had had a midair, both pilots grabbed the controls to roll her back, did someone say startle effect? Unfortunately accident reports are rather dry accounts and don't relate what it was like to be there, does the sim replicate anything that could be called a snap roll upon failure? The engine vibration was such that it caused the intake cowling to separate causing massive drag, hence the aircraft reaction.

[jlsmith]

According to Reuters, NTSB has the CVR in Washington for downloading

[EDLB]

Here:
https://www.reuters.com/business/aerospace-defense/us-ntsb-team-departs-china-take-part-boeing-crash-probe-2022-04-01/

[Sandlandman]

Wasn’t the FZ incident in Rostov an -800 nosedive with runaway trim wheel as a potential causative factor

[Bergerie1]

megan, That video in your post 313 illustrates exactly what I have been writing on another thread about simulators being unable to reproduce the 'startle effect' and acceleration forces of the real world incident/accident. UPRT has its uses but, with the best will in the world, it cannot compare with reality.

[Stick Flying]

Wasn’t the FZ incident in Rostov an -800 nosedive with runaway trim wheel as a potential causative factor
Nope, it was deliberate trim due to spatial disorientation.

[PJ2]

megan, Bergerie1 has kindly responded and I would agree with the assessment regarding simulators. The sim can produce very sharp "responses", including vibration, rapid changes in yaw, pitch etc., engine or tail scrapes and hard landings. On "dry" accident reports, it is impossible to write in a report on behalf of someone else who may or may not be alive, "what it was like". There is a long history of striving for factual reporting which has led to remarkable advances in data-capture & gathering. This one goal enables investigators to get as close to what happened and why so changes, improvements and validations of design, standard operating procedures, regulations etc., can reasonably be made. The science of human-factors acknowledges startle as a factor in behaviour but in the abstract. It's all quite dry for a good reason.

Sailvi767, re your comment: "The Southwest aircraft yawed and rolled because the engine suffered a uncontained catastrophic failure causing extensive cowling damage that dramatically increased airframe drag. Even given it was at a high thrust level and the aerodynamic drag it was easily controllable. That’s a very different scenario than what we know about China Eastern.".

Yes, agree. I believe that's essentially what I said in the post you have quoted: The SW B737 engines would have been in climb thrust, not cruise thrust. Thrust produced by the engines for the climb is greater than that required in cruise so loss of a higher level of thrust would certainly be noticeable to the crew and the airplane would respond more firmly to the assymetric thrust.

The report paragraph you quote states that the First Officer had the aircraft under control, returning the bank angle from 41° to 5° within 6 seconds. That was the point in my post - engine failure will cause yaw but in all ordinary, (uncomplicated) circumstances, is controllable whether on takeoff, climb, cruise, descent and approach. The event is practised in the simulator every six months or so...There is no observable reason to compare either of the above events with the China Eastern accident.

[A0283]

@jlsmith - CVR now with NTSB in Washington - According to Reuters, NTSB has the CVR in Washington for downloading

Chinese state media reported earlier that the CVR memory was so damaged that it had to be sent back to the manufacturer. Would make sense to do that via the NTSB.

[H Peacock]

So, back to the crewing. Was the 30k+ hr RHS FO a China Eastern captain that had lost his command due to previous flying related incidents?

If so, it potentially makes for an interesting dynamic on the flightdeck!

[FlightDetent]

So, back to the crewing. Was the 30k+ hr RHS FO a China Eastern captain that had lost his command due to previous flying related incidents?That particular incident (wrong QNH for NPA) is not confirmed to had been him, yet the demotion was a storyline from the beginning.

To my understanding CAAC News won't mistake RHS LTI for an F/O.

Although 60 may be and probably is the PIC age limit.

​​​​​​

[F3LD]

So, back to the crewing. Was the 30k+ hr RHS FO a China Eastern captain that had lost his command due to previous flying related incidents?

If so, it potentially makes for an interesting dynamic on the flightdeck!

Reminds me of egypt air 990

[Auxtank]

So, back to the crewing. Was the 30k+ hr RHS FO a China Eastern captain that had lost his command due to previous flying related incidents?

If so, it potentially makes for an interesting dynamic on the flightdeck!

Really would be great if you read the Thread before spouting in.

We've established the Training Captain (he wasn't the FO) with the long hours was Jump Seating.

[Lost in Saigon]

Really would be great if you read the Thread before spouting in.

We've established the Training Captain (he wasn't the FO) with the long hours was Jump Seating.

Have we established if that high time pilot (Zhang Zhengping) was demoted for a ground proximity incident and a failed SIM evaluation?

[Sailvi767]

So, back to the crewing. Was the 30k+ hr RHS FO a China Eastern captain that had lost his command due to previous flying related incidents?

If so, it potentially makes for an interesting dynamic on the flightdeck!

It becomes even more interesting if he was flying with the son of the man who made the decision to demote him.

[FlightDetent]

We've established the Training Captain (he wasn't the FO) with the long hours was Jump Seating.The you of 'we' is wrong.
CM1 Young talent captain
CM2 Retiree F/O, overqualified (unclear reasons)
CM3 Cadet
​​​​​

[FlightDetent]

Have we established if that high time pilot (Zhang Zhengping) was demoted for a ground proximity incident and a failed SIM evaluation?That is still single source, despite being a coherent story. The blog post was pushing a pre-planned murder+suicide narrative to score a political point.

Also the rumors of in excess of a dozen CEAir crewmembers positioning only flashed once, immediately in the afternoon.

[FlightDetent]

the man who made the decision to demote him.Technically, this is exactly how it works not in the PRC. Everything is a joint, comittee decision. To illustrate, for a business contract it is the stamp that matters, not the signature. ​TREs are not allowed to fail a candidate without approval. Etc.

Not ruling out a revenge motiff, just pointing out the local custom.

[Sailvi767]

Technically, this is exactly how it works not in the PRC. Everything is a joint, comittee decision. To illustrate, for a business contract it is the stamp that matters, not the signature. ​TREs are not allowed to fail a candidate without approval. Etc.

Not ruling out a revenge motiff, just pointing out the local custom.

Thats not how people I know working there in non airline jobs see it working. The have committees for everything. They are rubber stamps for the real person in charge.

[FlightDetent]

Don't know. Just assume/reflect that demoting a poster-instructor would need to include a CCP panel, worker's union council plus the flight ops management team of the local base and the HQ as well as agreement of their POI. After all, this is a government-run airline. Some of the stability and persistence comes from the stakeholders opposing each other. What's agreed becomes cast in stone.

Of course, if the suicide turns out to be true then logic would not have played a major role.

Kindly consider the edge of my previous post unnecessary as well as unintentional.

[LTC8K6]

This story states that both recorders were sent to the NTSB.

The safety board has said it was assisting the Civil Aviation Administration of China with the download of the cockpit voice recorder at its lab in Washington, but wouldn’t be releasing any information about its contents. The NTSB also hasn’t commented on whether the download was successful.

The flight-data recorder, which captures hundreds of parameters monitoring an aircraft’s path and systems, was also brought to Washington by the Chinese, a person familiar with the process said last week.

Seattle Times

[A0283]

This story states that both recorders were sent to the NTSB. Seattle Times


Chinese official sources during the SAR operation clearly stated a number of times that the recorders would be send to Beijing for download and analysis.

As I posted earlier there was note of more serious damage to the CVR can than at first impression and needed manufacturer involvement (Honeywell). So the same might be true for the FDR now. The FDR can having been recovered days later after being exposed to rainy conditions.Both cans showed similar scratching damage and a little bending at one flat end, but no exposure to fire it seems.

If the recorders were not compromised during an earlier attempt (there always is a risk), then this may point to a longer time before analysis may be started.

[Less Hair]

This might be just the typical technical assistance to just download the recorders. It doesn't change the Chinese civil aviation authority leading the investigation.

[procede]

They probably 'only' need to transfer the memory modules to a another circuit board.

[DaveReidUK]

This might be just the typical technical assistance to just download the recorders. It doesn't change the Chinese civil aviation authority leading the investigation.

Correct. Investigation protocol means that the NTSB will not make any announcements re findings.

[A0283]

This might be just the typical technical assistance to just download the recorders. It doesn't change the Chinese civil aviation authority leading the investigation.

@less hair - of course, it does not change the lead,

As dave says - all according to the well known procedures,… indeed,

@procede - I think the damage is more than that, … putting chips on another board is something you expect the Chinese are well capable of (can always send the required board) … after proper drying and such… but hope we will find out more later,

[procede]

@procede - I think the damage is more than that, … putting chips on another board is something you expect the Chinese are well capable of (can always send the required board) … after proper drying and such… but hope we will find out more later,
I think this is a case of "you do not want to mess it up, so you really want to leave it with those who have most experience with repairing it". And (de)soldering chips is something you have be really careful with as you do not want to overheat them.

[EDLB]

Can be that even some memory IC are damaged. The Chinese have surely some capability in this case but I would send it to the manufacturer because they know best what to do to get to the data. You can easily destroy existing data with wrong methods. At least it shows, that the CAAC takes this serious to get to the truth.

[logansi]

While I have to be careful because I'm only getting info directly from current CE employees, at least internally the reason being given for the 3rd crew and the captain flying as a F/O is all about Covid. Effectively I've been told by former students of mine (Cadets for 3 Chinese airlines) that most domestic flights are being crewed by 3 pilots with all 3 pilots logging time due to the current downturn with covid and company minimum hour requirements.

Again without naming the company or person at least 1 of my contacts (A recently type rated 320 F/O) is that for the last 3 months every flight has had 2 Captains flying and him logging F/O time from the jumpseat.

[FlightDetent]

Eh, need to check with them if there used to be 3 pilots on most domestic flights also before COVID (yes). Logging the jumpseat is normal because it is an official duty, although keeping captains current for take-offs and landings first does make sense.

Not blaming the messenger, the concept of 'least painful logically acceptable explanation' is well established and sadly aims to disconnect from analytical truth / causality.

[logansi]

Eh, need to check with them if there used to be 3 pilots on most domestic flights also before COVID (yes). Logging the jumpseat is normal because it is an official duty, although keeping captains current for take-offs and landings first does make sense.

Not blaming the messenger, the concept of 'least painful logically acceptable explanation' is well established and sadly aims to disconnect from analytical truth / causality.

Yes 3, even 4 crew in a cockpit is relatively normal. 2 Captains almost always operating a flight while actual F/Os as rostered as jump seaters is not normal. Again whether it's the reason, in this case, is completely unknown and the other explanation if the source is correct is definitely plausible, in fact, it would take a lot less than a terrain warning GPWS callout (upsetting a F/O whom has contacts in management could get you demoted). But at the same time, I've personally witnessed a F/O pass a type rating despite descending below MDA and having to be reminded on the MDA. (Someone didn't know I understood basic mandarin i think)

Also to whomever I read above saying their sims are hard I can agree, I was part of a management group that visited one of our contract airlines pre covid - our Head of Ops was a prior 737 Captain and commented on the standard expected of cadets, especially on your more specific emergencies like runaway trim and hydraulic failure - also some near impossible combinations of failures eg. V1 engine failure and runaway trim passing 2500 feet with flaps jammed

[silverelise]

South China Morning Post:
The head of China’s Civil Aviation Administration has vowed to deeply reflect on all aspects of the deadly crash of flight MU5735 and step up safety checks with “extreme” vigilance across the industry.
Speaking in a teleconference on Wednesday, Feng Zhenglin, director of the Civil Aviation Administration, directed officials to increase their knowledge of aviation safety regulations and to carry out more thorough inspections to detect hidden risks.

Interesting comments - is he alluding to a possible maintenance-related oversight or technical issue being a possible cause?
I note an earlier post in the thread saying that the aircraft was on the ground for 2 days prior to the day of the accident. Was it in maintenance?

[A0283]

South China Morning Post:
The head of China’s Civil Aviation Administration has vowed to deeply reflect on all aspects of the deadly crash of flight MU5735 and step up safety checks with “extreme” vigilance across the industry.
Speaking in a teleconference on Wednesday, Feng Zhenglin, director of the Civil Aviation Administration, directed officials to increase their knowledge of aviation safety regulations and to carry out more thorough inspections to detect hidden risks.

Interesting comments - is he alluding to a possible maintenance-related oversight or technical issue being a possible cause?
I note an earlier post in the thread saying that the aircraft was on the ground for 2 days prior to the day of the accident. Was it in maintenance?

You mean that FR24 did not register a flight on the 17th and the 19th in the period 14-21st. So the 2 days were not consecutive.
Also (for completeness) note that FR does not appear to show maintenance flights. They regularly do show manufacturing (production test) flights.

[BuzzBox]

South China Morning Post:
The head of China’s Civil Aviation Administration has vowed to deeply reflect on all aspects of the deadly crash of flight MU5735 and step up safety checks with “extreme” vigilance across the industry.
Speaking in a teleconference on Wednesday, Feng Zhenglin, director of the Civil Aviation Administration, directed officials to increase their knowledge of aviation safety regulations and to carry out more thorough inspections to detect hidden risks.

Interesting comments - is he alluding to a possible maintenance-related oversight or technical issue being a possible cause?
I note an earlier post in the thread saying that the aircraft was on the ground for 2 days prior to the day of the accident. Was it in maintenance?

I doubt it. These motherhood-type statements are fairly typical of the CAAC. They implemented a two-week nationwide inspection of all parts of China's aviation industry immediately after the accident, in response to Xi Jinping's directive to "strengthen the safety overhaul of the civil aviation sector to ensure the absolute safety of the sector and people's lives".

Global Times:
Chinese airlines take concrete measures to strengthen flight safety after crash (https://www.globaltimes.cn/page/202203/1256548.shtml)

[Gary Brown]

South China Morning Post:
The head of China’s Civil Aviation Administration has vowed to deeply reflect on all aspects of the deadly crash of flight MU5735 and step up safety checks with “extreme” vigilance across the industry.
Speaking in a teleconference on Wednesday, Feng Zhenglin, director of the Civil Aviation Administration, directed officials to increase their knowledge of aviation safety regulations and to carry out more thorough inspections to detect hidden risks.

Interesting comments - is he alluding to a possible maintenance-related oversight or technical issue being a possible cause?
I note an earlier post in the thread saying that the aircraft was on the ground for 2 days prior to the day of the accident. Was it in maintenance?

What does seem to be the case is that, of all airlines, Chinese or not, only China Eastern has grounded its 737-800 fleet. Other Chinese airlines are still operating them "as normal" and, afaik, the Chinese CAA (nor anyone else) has issued no general instructions or bulletins regarding the 737-800.

[sSquares]

It might be as complex as rewiring the integrated circuit pins to the silicon pads due to the large g-forces. If the silicon itself is fractured - then almost no chance of recovery.

[Willstone]

Squares, by cracked silicone do you mean the case or the die itself ?
If the case is cracked you can " decap " the dies from the case an transplant it
if it's cracked thru the die, then yes, game over.

[PJ2]

It might be as complex as rewiring the integrated circuit pins to the silicon pads due to the large g-forces. If the silicon itself is fractured - then almost no chance of recovery.The Germanwings 9525 deliberate crash in the French Alps in March, 2015 may hold relevant information & datapoints regarding chip survivability. Both trajectories were near-vertical at very high speeds. In a February 20, 2017 paper entitled "Texas A&M-Led Team Uses Mathematical Modeling to Explain Complete Destruction of Germanwings Flight 9525 (https://science.tamu.edu/news/2017/02/texas-am-led-team-uses-mathematical-modeling-to-explain-complete-destruction-of-germanwings-flight-9525/)", the pattern of destruction of the Germanwings aircraft is studied, (link to the actual paper, behind an academic wall, is here (https://iopscience.iop.org/article/10.1088/1402-4896/aa593a)). The BEA Report, English version, is here (https://www.bea.aero/uploads/tx_elyextendttnews/BEA2015-0125.en-LR_04.pdf).

While there may be a different focus to the study referenced above, it is encouraging to know that both recorders' chips survived the very high-speed impact with solid-rock and were readable (four days' later). The WQAR, (Teledyne) was X-Ray'd and found not usable.

NOTE CAVEAT: Other than the point being made regarding chip survivability, NO comparison between these two events is implied or intended. It remains unknown why and how the China Eastern accident occurred.

[alf5071h]

A simpler view of why the recorders have been sent to the US is to apply the original manufacturers flight test data calibrations. An important activity at the time of download given that it might be a one-shot opportunity due to damage.

Many years ago the most damaged recorder analysed was that extracted from the San Louis Obispo fatal accident. Pax / engineer shot the crew, then ‘vertical dive’ suicide. NTSB had the recorder on display in the entrance of their Washington DC HQ

[krismiler]

I wonder if this could be related.?

https://www.straitstimes.com/asia/se-asia/malaysias-civil-aviation-authority-to-probe-malaysia-airlines-over-erratic-flight-incident
KUALA LUMPUR - The Civil Aviation Authority of Malaysia (CAAM) will probe the flight data of a Malaysia Airlines flight involving a Boeing 737-800 plane after it allegedly dove suddenly and flew erratically before turning back on Sunday (April 3) (https://www.straitstimes.com/asia/se-asia/malaysia-airlines-flight-allegedly-dives-then-turn-back-to-kl-airport).

CAAM chief executive Chester Voo Chee Soon said the authority would be reviewing the internal flight data monitoring system of Flight MH2664 to get to the bottom of the issue.

"Preliminary data has shown correct responses by the operating crew following the issue onboard," Captain Voo said in a statement on Tuesday.
​​​​​

[BuzzBox]

I wonder if this could be related.?

https://www.straitstimes.com/asia/se-asia/malaysias-civil-aviation-authority-to-probe-malaysia-airlines-over-erratic-flight-incident

The FR24 plot for that flight (MH2774/03Apr) shows the aircraft turned back to KUL about 35 minutes after take-off. The altitude trace shows a 'blip' about 18 minutes after take-off, where the altitude changed suddenly from 25,000 ft to 23,375 ft and back to 25,000 ft. There's a second, smaller excursion about 7 minutes later, where altitude changed from 29,000 ft to 28,275 ft and back to 29,000 ft. The aircraft turned back to KUL about 5 minutes after the second altitude excursion and climbed to 30,000 ft. The remainder of the flight appears to be uneventful.

​​​​​​​https://www.flightradar24.com/data/flights/mh2664#2b5da11b

[Stick Flying]

Yep, Looks unrelated to me. Unless of course you would continue after an "unexplained and uncontrolled" couple of descents.

[AAKEE]

Yep, Looks unrelated to me. Unless of course you would continue after an "unexplained and uncontrolled" couple of descents.

Yup, not related. Theres no left roll present.

MU5735 and SJ182 is carbon copies.

SJ had a Autothrottle failure.

[grizzled]

AAKEE...

I can certainly see why someone would say MH2774 and this China Eastern accident are very likely unrelated (though to declare "yup, not related" at this stage is not something an aircraft accident investgator is apt to say).
But to say, "MU5735 and SJ182 is carbon copies" is a giant stretch, even for an investigator familiar with these and "similar" accidents.. Care to expand on that?

[pattern_is_full]

The Germanwings 9525 deliberate crash in the French Alps in March, 2015 may hold relevant information & datapoints regarding chip survivability. Both trajectories were near-vertical at very high speeds, (between 4 & 7 "fuselage lengths per second").

The Germanwings crash was hardly "near-vertical." Perhaps we can leave the exaggeration to the media.

Descent rate was ~3500 fpm and took about 10 minutes from top of descent to impact. Roughly a 30° glide path, over a ground track of about 60-70 nm.

It did, of course, hit a steep mountainside, so the impact angle was closer to 70° or so - and was at high speed.

[vilas]

The Germanwings crash was hardly "near-vertical." Perhaps we can leave the exaggeration to the media.

Descent rate was ~3500 fpm and took about 10 minutes from top of descent to impact. Roughly a 30° glide path, over a ground track of about 60-70 nm.

It did, of course, hit a steep mountainside, so the impact angle was closer to 70° or so - and was at high speed.
Airbus cannot be put in attitude beyond -15° pitch. So no question of vertical dive. It was just a planned descent.

[AAKEE]

AAKEE...

I can certainly see why someone would say MH2774 and this China Eastern accident are very likely unrelated (though to declare "yup, not related" at this stage is not something an aircraft accident investgator is apt to say).
But to say, "MU5735 and SJ182 is carbon copies" is a giant stretch, even for an investigator familiar with these and "similar" accidents.. Care to expand on that?

Yes.

I should have written that the initial upset is carbon copies.

If the FR24 log is viewed in 3D both these accidents show a reduced groundspeed during the initial upset. There is a not insignificant left movement that can only be explained by a left roll. The height loss and the parallell movement during the first half roll is the same. The dive angle is not that different and the continued roll is very like each other. MU5735 began the upset with higher speed, and also did loose a little more altitude during the roll/tunnel roll.

[pilotmike]

The Germanwings crash was hardly "near-vertical." Perhaps we can leave the exaggeration to the media.

Descent rate was ~3500 fpm and took about 10 minutes from top of descent to impact. Roughly a 30° glide path, over a ground track of about 60-70 nm.
Descending at 3500fpm taking 10 minutes (around 30,000 to 35,000') covering 60-70NM CERTAINLY ain't a 30 degree descent, more like closer to 6 degrees.

So in your own words, "Perhaps we can leave the exaggeration to the media".

[PJ2]

pattern is full, vilas, thanks for your responses regarding my characterization of the descent - I agree with you both and my over-eager post describing the Germanwings descent has been corrected, (strike-out of "near-vertical").

The point being made in the post, "...it is encouraging to know that both recorders' chips survived the very high-speed impact with solid-rock and were readable (four days' later).", stands of course and remains encouraging, at least until we hear otherwise.

[Wannabe Flyer]

It has been a while & there is a silence on the contents of the CVR & FDR.......(Definitely more than 4 days later now)

[epi]

CAAC is having a PR hard time. So you know the reason…
It has been a while & there is a silence on the contents of the CVR & FDR.......(Definitely more than 4 days later now)

[tdracer]

It has been a while & there is a silence on the contents of the CVR & FDR.......(Definitely more than 4 days later now)
Any information release would need to come from the Chinese investigative authority. While the NTSB, Boeing, CFM, etc. are all involved, they are basically under a gag order prohibiting them from any information release, regardless of what they may know.

[Teddy Robinson]

It has been a while & there is a silence on the contents of the CVR & FDR.......(Definitely more than 4 days later now)

An intermediate report will be forthcoming within 30 days.
This has already been stated, and is the industry norm.

TR

[SteinarN]

Leeham in a subscription article states that investigators are leaning towards suicide as the cause of the crash.

China Eastern crash cause appears trending toward pilot suicide.

https://leehamnews.com/2022/04/11/airbus-nears-finding-homes-for-air-asia-x-aerospace-widebodies/

[procede]

Suicide with two other (much younger and fitter) pilots in the cockpit seems a bit unlikely to me.

[INSCRINIUM]

Leeham in a subscription article states that investigators are leaning towards suicide as the cause of the crash.


That last bullet with the suicide claim seems weirdly disconnected from the rest of the article ?

[Fonsini]

Suicide with two other (much younger and fitter) pilots in the cockpit seems a bit unlikely to me.

If it was the Captain I’m sure that he could have found a reason to get them both out of the cockpit.

[WideScreen]

That last bullet with the suicide claim seems weirdly disconnected from the rest of the article ?
Just sensational.

Lookup the original Leeham article in March and you'll see, they did just copy the last (bullet) line from that article. The other bullets in that article refer to other options also passed on PP.

[PJ2]

An intermediate report will be forthcoming within 30 days.
This has already been stated, and is the industry norm.

TR
...and there are no directives requiring early attention or urgent action on the part of B737 operators

[procede]

If it was the Captain I’m sure that he could have found a reason to get them both out of the cockpit.

If it was anyone that committed suicide, it was the captain demoted to first officer.

[Organfreak]

I know that it's happened before, but any pilot who deliberately crashes his plane is also that very rare bird, a mass murderer.

[sSquares]

Squares, by cracked silicone do you mean the case or the die itself ?
If the case is cracked you can " decap " the dies from the case an transplant it
if it's cracked thru the die, then yes, game over.

The case is not silicon.

[WideScreen]

If it was the Captain I’m sure that he could have found a reason to get them both out of the cockpit.
With only one person in the Cockpit, a suicide mission would not have had a successful (!) recovery halfway down to the ground.

[WideScreen]

...and there are no directives requiring early attention or urgent action on the part of B737 operators
For a directive, it would need an understanding of what happened and why it happened. For something happening on automation, that might need some time to figure out.

[Majorbyte]

Suicide with two other (much younger and fitter) pilots in the cockpit seems a bit unlikely to me.
really? it would take just a few moments, very little two 'fitter' pilots could do to stop it.

[mrdeux]

Airbus cannot be put in attitude beyond -15° pitch. So no question of vertical dive. It was just a planned descent.
Of course it can. Just not in normal law.

[ivorget]

From Chinese TV channel CGTN on twitter today: (can't post link yet)

China denied rumors the MU5735 flight co-pilot is to blame for the crash, an official with the Civil Aviation Administration of China said at a news conference on Monday, adding those who spread rumors would be held accountable.

[PJ2]

For a directive, it would need an understanding of what happened and why it happened. For something happening on automation, that might need some time to figure out.
Yes, understand that, thanks. Likely you know this, but sometimes in the course of early investigation, the DFDR may reveal something that could be of an immediate airworthiness concern. If readable or partially-so, I suspect by this time they may have an inkling of what happened and that it is, again likely, that it is not a type or fleet-wide matter. Also, I am taking into account who is in charge of the investigation in terms of the relative silence but the Chinese have indicated a 30-day report will be issued. That nothing by way of implementable procedure or technical change has been issued may be construed as a positive sign. Just grasping at straws like everyone else, believing that, "no news is 'good' news", I suppose.

[WideScreen]

Yes, understand that, thanks. Likely you know this, but sometimes in the course of early investigation, the DFDR may reveal something that could be of an immediate airworthiness concern. If readable or partially-so, I suspect by this time they may have an inkling of what happened and that it is, again likely, that it is not a type or fleet-wide matter. Also, I am taking into account who is in charge of the investigation in terms of the relative silence but the Chinese have indicated a 30-day report will be issued. That nothing by way of implementable procedure or technical change has been issued may be construed as a positive sign. Just grasping at straws like everyone else, believing that, "no news is 'good' news", I suppose.
Yep, an initial pretty plausible indication of what has happened, may trigger these early notifications, etc.

For now, we do have the situation the MU B737 fleet is still not returned to service. Suggesting, IF the CVR is indeed read out, the cause of this tragedy is not a deliberate human aspect, but more technical (weather and all kinds of other fantasies can be ruled out, I think).

TBH, I don't expect China to release anything from the CVR. China does have stringent privacy regulations (effectively, though, unless when the state itself is involved).

So, yeah, for now, we need to wait a couple of days. If no further notices are released, either the FDR can not be read, or this incident is not a copy cat of earlier incidents with a recognizable cause.

[silverelise]

For now, we do have the situation the MU B737 fleet is still not returned to service.

Is that confirmed? FR appears to show MU 737s operating flights today.

[WideScreen]

Is that confirmed? FR appears to show MU 737s operating flights today.
While preparing my post about this, I checked around 20 frames (the newer ones) and none of these did fly in April. Checking again for you, now for nearly all, none of these did fly in April. All B737-800, the crashed version.

Checking for MU B737-700, you can see, these do fly (regularly), so I assume, this is what you saw.

[SATCOS WHIPPING BOY]

With only one person in the Cockpit, a suicide mission would not have had a successful (!) recovery halfway down to the ground.
Partial recovery or a glitch in pressure data implying a temporary climb?

My thoughts are it was plummeting, and the FR data shows a drop in pressure rather than a physical climb. It's a long time since I did any altimetry but isn't the data fed by a static vent? Orient the aircraft body so that vent is in a low pressure air-flow (rolling and falling) and you get the apparent increase in altitude. ???

[WideScreen]

Partial recovery or a glitch in pressure data implying a temporary climb?

My thoughts are it was plummeting, and the FR data shows a drop in pressure rather than a physical climb. It's a long time since I did any altimetry but isn't the data fed by a static vent? Orient the aircraft body so that vent is in a low pressure air-flow (rolling and falling) and you get the apparent increase in altitude. ???
By wobbling around the aircraft nose, you can get some variations in pressure indication, though not that much as the FR24 data shows. If your theory would be valid, the wobbling would be able to distort the altitude measuring in the 5000-th feet, and that, during a steep decent. Also, when the nose stops wobbling, there is no catch-up visible in the FR24 data, so no sudden discontinuity, graphically showing a drop of 10000 feet (in the end, the recording roughly stops at terrain height). Just make a altitude graph yourself and you'll see, it's all pretty smooth. I think, theory busted.

Oh, and at those speeds, don't wobble the nose around to much, otherwise you may loose your tail-end, if not, even shred the aircraft.

[SATCOS WHIPPING BOY]

Thanks Widescreen. I take your point about the no catch up; just musing that a 1200ft gain is roughly a 40millibar drop in pressure.

Guess we'll just have to see what the end report has to say.

[grizzled]

For a directive, it would need an understanding of what happened and why it happened. For something happening on automation, that might need some time to figure out.WideScreen (and others that are fairly new to pprune)... With all due respect, you may want to click on a poster's public profile before you reply to one of their posts. And perhaps even look at some of their inputs to previous accident threads. To put it more simply, telling PJ2 what is needed for a directive to be issued is like telling a fish how to swim...

Cheers!

[AAKEE]

Just make a altitude graph yourself and you'll see, it's all pretty smooth. I think, theory busted.

Oh, and at those speeds, don't wobble the nose around to much, otherwise you may loose your tail-end, if not, even shred the aircraft.

Yes. Even better than plotting a 2D graph is to use google earth or similar to make a 3D graph from the granular data. It is very informative.

[WideScreen]

Yes. Even better than plotting a 2D graph is to use google earth or similar to make a 3D graph from the granular data. It is very informative.
Yep Google Earth is very valuable for the impression, but less for the analytics. Plotting a cloud of dots in just 2D in LibreOffice or so, gives the analytics part. Just take care to handle the time axis properly, and you see many more aspects than in a fancy Google 3D view.

For example: Data points like the Long/Lat give a nice straight line (especially for the first half of the down to earth trajectory) with just one small "S-curve" in it. Practically suggesting, the chance, there are 360's involved is pretty low. And, these data points being subject to aliasing with a max cycle of 30 seconds based on a 50+ ton passenger aircraft movements, is also quite unlikely.

[WideScreen]

WideScreen (and others that are fairly new to pprune)... With all due respect, you may want to click on a poster's public profile before you reply to one of their posts. And perhaps even look at some of their inputs to previous accident threads. To put it more simply, telling PJ2 what is needed for a directive to be issued is like telling a fish how to swim...

Cheers!
Maybe, I am less "new" to PP, than you assume. Think about 15+ years of lurking, before signing up and even then, not posting. Postings from PJ2, tdracer and several others are very interesting to read, so to say.

Oh, cheers (although, I don't drink myself).

[DaveReidUK]

Yes. Even better than plotting a 2D graph is to use google earth or similar to make a 3D graph from the granular data. It is very informative.

I plotted a GE 3D trajectory when the data became available (similar to the one subsequently posted). I didn't post it because the data is sparse and it didn't strike me as particularly informative ...

[PuraVidaTransport]

My problem with the suicide theory is timing. They were at top of decent which tells me all pilots should be in the cockpit. I doubt even a Chinese captain could come up with an excuse good enough to get the other two pilots out of the cockpit just as they are about to begin the decent. Perhaps I'm wrong and they do things differently in China but I can't imagine any professional crew leaving one pilot alone during such a critical time.

[V1]

I remember years ago descending into CDG around 15,000 ft in a 737, when both altimeters suddenly ran down to zero and then back to the correct altitude within about 2-3 seconds. Unfortunately during this apparent descent the autopilot “captured the cleared descent altitude” we had preset (somewhere around 6,000 ft) … and then once we were “back at 15,000 ft” the started a rather aggressive dive back down towards the captured altitude, which I was only able to stop quickly by disconnecting the automatics … before resetting various (altitude & modes) and re-engaging autopilot & A/T.
Then had the same thing happen about 2 weeks later.
Although ASR’d at the time I don’t remember ever getting to the bottom of what caused it although my suspicion has always been that it had something to do with mobile phones being turned on (give away “nya-nya-nya” chirp radio interference around the same time).

[AAKEE]

I plotted a GE 3D trajectory when the data became available (similar to the one subsequently posted). I didn't post it because the data is sparse and it didn't strike me as particularly informative ...

When you did your 3D trajectory check, you did see a parallel movement from the last point before the upset until the first point with altitude loss that is in the order of 1600m. During these 15-20s the aircraft moved much more to the left (seen in the direction of
flight) than it lost altitude. The following points also show the same lateral displacement. It was not a position glitch.

Many other (except we two), only did look at the course that seem to not have changed and from this they probably did draw the not correct conclusion that the aircraft did continue straight ahead with a nose down input. Which it did not.

The lateral displacement to the left need a (steep) left bank to take place. This part you will not see on a 2D dive profile from the side.

The SJ182 accident have the same lateral displacement (also 1600m) but that ADS-B track do not have a gap of 15-20s during the turn so for SJ182 those points show the left roll leading to the inverted dive/barrel roll.

Without 3D, or at least looking at this with 2d from both the side and from above, you wint notice the lateral displacement to the left that tell us that a left roll had a dominant part of the upset.

MU5735 initiated the upset by a left roll with positive G, probably just what we would see if a pilot get disoriented and fly a about 1G seat of the pants pitch during the roll.
The dive following the lateral displacement is probably inverted initially and the about 1G barrel roll continue until the aircraft is almost right on the wings again.

Engine failure, Auto throttle failure or something that caused the initial part of the roll followed by spatial disorientation or a IRS failure maybe.

[DaveReidUK]

When you did your 3D trajectory check, you did see a parallel movement from the last point before the upset until the first point with altitude loss that is in the order of 1600m. During these 15-20s the aircraft moved much more to the left (seen in the direction of
flight) than it lost altitude. The following points also show the same lateral displacement. It was not a position glitch.

Many other (except we two), only did look at the course that seem to not have changed and from this they probably did draw the not correct conclusion that the aircraft did continue straight ahead with a nose down input. Which it did not.

The lateral displacement to the left need a (steep) left bank to take place. This part you will not see on a 2D dive profile from the side.

The SJ182 accident have the same lateral displacement (also 1600m) but that ADS-B track do not have a gap of 15-20s during the turn so for SJ182 those points show the left roll leading to the inverted dive/barrel roll.

Without 3D, or at least looking at this with 2d from both the side and from above, you won't notice the lateral displacement to the left that tell us that a left roll had a dominant part of the upset.

MU5735 initiated the upset by a left roll with positive G, probably just what we would see if a pilot get disoriented and fly a about 1G seat of the pants pitch during the roll.
The dive following the lateral displacement is probably inverted initially and the about 1G barrel roll continue until the aircraft is almost right on the wings again.

Engine failure, Auto throttle failure or something that caused the initial part of the roll followed by spatial disorientation or a IRS failure maybe.

The FR24 "granular data" contains only 18 data points covering the last 2 minutes of flight, from FL290 until contact lost, so about 7 seconds apart on average.

I'd want to see at least 5x as many data points before attempting to draw any conclusions about the detailed trajectory during the upset.

[AAKEE]

The FR24 "granular data" contains only 18 data points covering the last 2 minutes of flight, from FL290 until contact lost, so about 7 seconds apart on average.

I'd want to see at least 5x as many data points before attempting to draw any conclusions about
the detailed trajectory during the upset.

Theres only 17 valid points for 3D, as one has
no position.

But there is at least 100 points on the straight and level flight before the upset of which everyone is on a perfectly straight line viewed in 3D. No hickups or glitches. Not even a minor imperfection.

There is a 16s gap between the last normal point and the first in the upset. From that mostly 5s gap and I’m sure 5s is close enough when the existing point describe a spiral, to see how the trajectory is in between these 5s gap. For example in a loop you could understand the pull up in the end of a loop with points 5s apart, as the only logic way is the rounded trajectory in between. What we see is a ”about” 1G barrel roll.
Maybe not exactly but not very far from this.
There is a couple of 10s gaps, produced by the lack of a single data point( loss of one per five seconds create a 10s gap between points) but the position of these lost datapoints do not really affect the possibility to understand what happened.
Why, is not that easy though.

The SJ182 initial upset is a carbon copy, the parallel displacement is the same, the initial altitude loss is about the same so the trajectory of SJ182 can be used to understand how Mu5735 got from the fine cruise on level to the first datapoint in the upset.

So we more or less know “what” but we do not have the “why”.

[WideScreen]

......
The SJ182 initial upset is a carbon copy, the parallel displacement is the same, the initial altitude loss is about the same so the trajectory of SJ182 can be used to understand how Mu5735 got from the fine cruise on level to the first datapoint in the upset.

So we more or less know “what” but we do not have the “why”.
Before the upset, MU5735 was flying nearly double the ground speed of SJ182. Ground speed is what counts for the kinetic and subsequent rotational energy of an object, implying nearly 4 (OK, maybe closer to 3.5) times the energy for MU5735. That increase in energy implies the same 3.5 times increase for the mass related forces involved and 2^3 (=8, round down to 6-7 for the effect of not completely the double ground speed) times for the aerodynamic forces involved.

Implying, significant g-forces are required to accomplish a 3D-360 within something like 12 seconds, immediately followed by another 40 seconds with good directional stability. Easy to accomplish, when being completely shaken by a probably completely uncoordinated 3D-360 and stiff controls, due to the high speed, the aircraft obtained.

Also, it does not explain, WHY this diving stage happened again, this time, without the S-curve (or assumed 3D-360).

From earlier experiences, we do know that rudder hard-over is a difficult to control item at low speed, not at high speed. Unpleasant, but manageable at high speed.

From earlier experiences, we do know, that aerodynamic engine damage does not (have to) lead to control issues. Again, unpleasant, but manageable.

We do know, the aircraft got "stable" on course again (and even recovered from the initial dive), so the aerodynamic damage to the aircraft isn't that big (at that moment).

[AAKEE]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/789x604/mu5735_rear_6f78e19873b2668a49faf869215199cd6db08b47.png
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1018x765/mu5735_side_78518d23c2bec74f4b418e374693334d8e3babd9.png
Before the upset, MU5735 was flying nearly double the ground speed of SJ182. Ground speed is what counts for the kinetic and subsequent rotational energy of an object, implying nearly 4 (OK, maybe closer to 3.5) times the energy for MU5735. That increase in energy implies the same 3.5 times increase for the mass related forces involved and 2^3 (=8, round down to 6-7 for the effect of not completely the double ground speed) times for the aerodynamic forces involved.

I have good understanding of kinetic energy etc.

1) The parallel displacement do not aquire any more G-force to move an object for example 1600m at 16 seconds if the speed is higher. Of course the trajectory will be spread out on a longer distance. Just as in the case of MU5735.
2) Rotational energy? There will be nothing that hinders a aircraft to roll for example 90 degrees in X seconds just because the groundspeed/airspeed is higher. The amount or roll per travelled distance will be lower though. Just as in the case of MU5735.


We do know, the aircraft got "stable" on course again (and even recovered from the initial dive), so the aerodynamic damage to the aircraft isn't that big (at that moment).

Do we know this ? The plot seems to be all over tha place after the pull up. My guess is that the Aircraft lost some aerodynamy abilities at the high speed pull up and lost the ability to controlled stable flight after the pull up.
During the left roll, the diving barrel roll and the pull upp there is a clear understandable trajectory, and the "low resolution" doesnt really matter to see the plot. After the pull up, the plot is not that easy to se and stable flight is not what I see.
If anything is to be said about the after pull up, it is that maybe the aircraft did continue to barrel roll and in that case continued to roll inverted and that the final part of the dive was inverted. There is another parallel displacement to the left,which might come from another half barrel roll. But there is a another 16s gap about that position so it is hard to "know" the trajectory at that point.

[AAKEE]

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/953x681/sj182_rear_d4faaa1f2867721ef1c638078156ac6af7b7d6d8.png
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/861x746/sj182_side_bf2ad0fea13578b534607ee58636369070d76066.png
This is the SJ182 equivalents of the MU5735 above. A few points hidden during the initial upset to create a similar gap.

Upper picture in both cases is from straight behind, viewed from the trajectory of the normal flight. The most right dot is several 3d points lining up in a perfect line, because of this we only see on dot.

We can see that SJ182 struck the water about in the middle of the original track and the 0.9Nm maximum displacement. Looking at the MU5735 we can see that when the altitude loss was similar to the SJ182 sturking the water, MU5735 also was about in the middle between the 0.9Nm displacement and the original track.

[MikeSnow]

Ground speed is what counts for the kinetic and subsequent rotational energy of an object

Wait, what? Speed is relative. As a result, kinetic energy is relative as well. Let's say you are sitting down in a train moving at a constant speed of 100 km/h relative to the ground, in a straight line. You as a passenger would have zero kinetic energy relative to the train frame of reference. And if the train wouldn't have any windows (and assuming you can't rely on noise either), you wouldn't even be able to tell if the train is stationary or is moving.

Now imagine you have a small drone, and you fly it inside that train. Again, it would be irrelevant if the train were moving at 100km/h or 200km/h relative to the ground, or if it were stationary. It would have no effect on the flight of the drone inside the train, and the G forces and aerodynamic effects it experiences.

[notmanyflyinghours]

Wait, what? Speed is relative. As a result, kinetic energy is relative as well. Let's say you are sitting down in a train moving at a constant speed of 100 km/h relative to the ground, in a straight line. You as a passenger would have zero kinetic energy relative to the train frame of reference. And if the train wouldn't have any windows (and assuming you can't rely on noise either), you wouldn't even be able to tell if the train is stationary or is moving.

Now imagine you have a small drone, and you fly it inside that train. Again, it would be irrelevant if the train were moving at 100km/h or 200km/h relative to the ground, or if it were stationary. It would have no effect on the flight of the drone inside the train, and the G forces and aerodynamic effects it experiences.

Mainly. But watch the wierd unexplainable forces on the drone when the train goes into a corner.

[procede]

Wait, what? Speed is relative. As a result, kinetic energy is relative as well. Let's say you are sitting down in a train moving at a constant speed of 100 km/h relative to the ground, in a straight line. You as a passenger would have zero kinetic energy relative to the train frame of reference. And if the train wouldn't have any windows (and assuming you can't rely on noise either), you wouldn't even be able to tell if the train is stationary or is moving.

Now imagine you have a small drone, and you fly it inside that train. Again, it would be irrelevant if the train were moving at 100km/h or 200km/h relative to the ground, or if it were stationary. It would have no effect on the flight of the drone inside the train, and the G forces and aerodynamic effects it experiences.
The earth is turning around its axis and around the sun. And then the sun is also moving with respect to the rest of the galaxy...

[Redbeard]

Well it seems that they have restarted using the 737-800 in China, so I guess even though no announcements have been made they must have discovered something that caused the accident,

[WideScreen]

Well it seems that they have restarted using the 737-800 in China, so I guess even though no announcements have been made they must have discovered something that caused the accident,
I checked for you on FR24, though, according FR24, only 5 out of the 105 MU B737-800 are SCHEDULED to fly on 18/4 or 19/4. And that is roughly the same qty as was scheduled for the same dates, a week ago. Only the MU B737-700 do fly. So, debunked.

Intriguing is, we don't hear anything about the CVR/FDR results. Given the MU B737-800 are still grounded, unless the CVR and FDR are not readable (unlikely), this accident does not seem to be a deliberate crew action.

[WideScreen]

Wait, what? Speed is relative. As a result, kinetic energy is relative as well. Let's say you are sitting down in a train moving at a constant speed of 100 km/h relative to the ground, in a straight line. You as a passenger would have zero kinetic energy relative to the train frame of reference. And if the train wouldn't have any windows (and assuming you can't rely on noise either), you wouldn't even be able to tell if the train is stationary or is moving.
....

Of course.
When you (with mass m) jump off the train with speed v-train, you are going to dissipate: 0.5*m*(v-train)^2.
When you run on the train, with v-run, and subsequently jump off, you are going to dissipate: 0.5*m*(v-train+v-run)^2 (and not 0.5*m*(v-train)^2 + 0.5*m*(v-run)^2).
When you run on the train, backwards, where v-run= - v-train and jump off, you are going to dissipate: 0.

So, debunked (and I leave out the rest of your reasoning, since that qualifies for the same).

[FlightDetent]

Intriguing is, we don't hear anything about the CVR/FDR results. Given the MU B737-800 are still grounded, unless the CVR and FDR are not readable (unlikely), this accident does not seem to be a deliberate crew action.The grounding inside the airline was a quick stop measure, safety is 100% achieved when planes don't fly. The fact that other airlines didn't until today nor Boeing / CAAC had released some memorandum suggests lacking evidence of a technical issue.

Answer why keep them grounded might be more simple than anything - the flight operation is so severely cut CEAir may be even keeping other types parked these weeks due lack of work.

[FlightDetent]

Down to 1/5 from last year's levels.

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/2000x901/screenshot_2022_04_17_19_03_52_277_com_feeyo_vz_pro_cdm_6ae3 ca7cdc03117d002bc0bccae987960718139a.jpg

[WideScreen]

Down to 1/5 from last year's levels.

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/2000x901/screenshot_2022_04_17_19_03_52_277_com_feeyo_vz_pro_cdm_6ae3 ca7cdc03117d002bc0bccae987960718139a.jpg
Add "Canceled" and "Flown" and you get roughly to the 2021 levels. So, there was a plan.

Shanghai and many other big China cities got into lock-downs or under travel-limitations outside the own environment, around 1 month ago.

So, yeah, these items made it easy for MU to swap out the B737-800 against other airplanes, for example the B737-700 and the A32x. Especially the A32x, MU does have quite a lot of these.

Though, effectively, MU still does not use the B737-800, whereas it can be expected that at least part of the routes could be served with this type, on busy days. But it isn't.

We just have to wait what is going to happen. Assuming the CVR/FDR are read-out by now and no other measures are announced (or taken by MU), more or less implies, it is unclear what happened. Or better, why this accident happened.

[Sailvi767]

I still find it interesting the Chinese government has offered no explanation for a 31,000 hour former CA flying as a FO on the trip.

[FlightDetent]

To avoid confusing someone, the above graph is the nation-wide domestic sectors, not only MU. Cutoff-point between not-planned against planned but cancelled is not clear.

The total planned count matches the volume of 2021 APR-JUL which was the same as 2019 BTW.

Online sources suggest before the crash around 40 of the -800 were in service compared to 60 stored, accompanied by 25ish -700 all in active service.
Whereas the single-aisle Airbus fleet had 300 active planes flying, above those parked.

40+30+400 = 470
470 / 3 (optimistic, double the real today's sector count) = around 150 planes needed and 320 left unused beyond those mothballed.

Keeping the 800s grounded altogether, with 40 hulls, is an irreleveant decision that costs nothing and has some marketing potential for damage control.

[FlightDetent]

I still find it interesting the Chinese government has offered no explanation for a 31,000 hour former CA flying as a FO on the trip.It hardly fits the calendar, does it? We tried to see how but actually it could work. Still expecting some findings if rigorous checking is perfomed, not that the world would learn about.

Assuming the senior ex-captain was a party poster icon, together with years served and higher age that gets you ahead and beyond everyone else. Keep in mind flight hours make money... Part 121 limits were 1000 annualy bfore 2020 and SIM on top of that yet that might be a part of the listed total experience, including teaching time.

Qatari and Emirates are squeezing 1400 hours from the boys, before factoring. If you're the top-brass surely you can do 8 hours SIM instruction for weeks without setting a foot in the pleasurebox, sharing the income with the junior TRI who would do the actual work .... you get my drift. Seen similar years after the deceased's prime time.

[WideScreen]

......Online sources suggest before the crash around 40 of the -800 were in service compared to 60 stored, accompanied by 25ish -700 all in active service.
I checked that for you. According FR24, all but one of the 109 B737-800 were in regular commercial service in the 2 weeks before 21/3/2022.
The same applies for the B737-700.
Whereas the single-aisle Airbus fleet had 300 active planes flying, above those parked.
I checked that for you. According FR24, MU does have 290 A319/320/321 airplanes.

40+30+400 = 470
470 / 3 (optimistic, double the real today's sector count) = around 15 planes needed and 320 left unused beyond those mothballed.

Keeping the 800s grounded altogether, with 40 hulls, is an irreleveant decision that costs nothing and has some marketing potential for damage control.
Given your starting figures are off, I think, the conclusion has become wobbly too.

[FlightDetent]

Perfect, thanks for straightening those.

I usually go here: https://www.planespotters.net/airline/China-Eastern-Airlines or here: https://www.airfleets.net/ageflotte/China%20Eastern%20Airlines.htm but landed in a different place this time and while it looked similar, it was neither of them. Used Bing, maybe that's why.

Not sure how to obtain numbers from FR24 but if they saw them fly surely they did. I honestly meant 150 planes needed not 15.
I checked that for you. According FR24, MU does have 290 A319/320/321 airplanes. Please have a second look: https://www.flightradar24.com/data/airlines/mu-ces/fleet, I see 361 single-aisle Airbii not 290 (my original source suggested 290 flying and 65 stored before the crash).

But you're right, adding 40+30+300 is not 470 :{ now I scared myself from reading that post again. Should have resulted in 125 required to fly the schedule.

These guys https://www.planespotters.net/airline/China-Eastern-Airlines indicate 106 pcs of -800 grounded alongside additional 163 A32x(n)s. Supports my suggestion CEAir has parked significantly more frames for commercial reasons than induced by the reaction to accident.

[dbenj]

I still find it interesting the Chinese government has offered no explanation for a 31,000 hour former CA flying as a FO on the trip.

I also find it interesting that the "aircraft part" discovered several miles from the crash site has not been confirmed to either be part of or not part of MU5735.

[FlightDetent]

CAAC data set:

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1080x1710/img_20220418_010931_b13d375257d9717788a64841f2ac8d1b42a7303e .jpg


Assuming 1900 domestic sectors for the last week, and with a conservative 3 daily legs per hull, the need is only for 90 airplanes. With all the grounded -800 already set aside they still have, in addition,361x n.b. airbus
40x 737-700
55x A330= 450 planes to fly the schedule (1/5 already seen in post #412)

[BuzzBox]

I checked for you on FR24, though, according FR24, only 5 out of the 105 MU B737-800 are SCHEDULED to fly on 18/4 or 19/4. And that is roughly the same qty as was scheduled for the same dates, a week ago. Only the MU B737-700 do fly. So debunked.

The following SCMP article claims China Eastern resumed -800 operations over the weekend:
https://www.scmp.com/news/china/politics/article/3174559/china-easterns-boeing-737-800s-back-air-after-march-crash

https://www.flightradar24.com/data/flights/mu5843#2b851efa

[tdracer]

Same with Rueters:BEIJING (Reuters) -China Eastern Airlines has started putting its Boeing 737-800 jetliners back in use for commercial flights less than a month since a crash killed 132 people and led the company to ground 223 of the aircraft, the carrier said on Sunday.
The airline said it had conducted systematic tests, structural checkups and verified airworthiness data for each of the aircraft, and that test flights would be carried out on all planes before they resumed commercial services.
Boeing 737-800 planes with registration numbers close to the one that crashed on March 21 are still undergoing maintenance checks and evaluation, the company told Reuters in a statement.
Flightradar24 data showed earlier in the day that China Eastern flight MU5843, operated by a three-year-old Boeing 737-800 aircraft, took off from the southwestern city of Kunming at 09:58 a.m. (0158 GMT) on Sunday and landed at 11:03 a.m. in Chengdu, also in southwestern China.
That aircraft, which completed a test flight on Saturday, later returned back to Kunming, according to Flightradar24.

Given the minimal differences between a 737-700 and -800, the grounding of only the -800 fleet was more symbolic than any real concern over the airworthiness of the 737-800 fleet.

[Carbon Bootprint]

From today's Wall Street Journal:

HONG KONG—China Eastern (https://www.wsj.com/market-data/quotes/CEA) Airlines said it has resumed passenger flights of its Boeing (https://www.wsj.com/market-data/quotes/BA) 737-800 model aircraft after grounding the planes for nearly a month, following a crash of one of the planes (https://www.wsj.com/articles/china-eastern-airlines-plane-crashes-in-guangxi-province-11647852654?mod=article_inline) that killed all 132 people on board.China Eastern said on Monday that while the airline’s Boeing 737-800 planes have resumed operations, it is still inspecting and conducting assessments on a batch of the 737-800 aircraft that were manufactured around the same time as the plane that had crashed.China Eastern’s grounding of the planes was an emergency measure to run system tests on each of the 737-800 aircraft to examine airworthiness data, a representative from the airline said. The company is also conducting flight tests for 737-800 planes, the representative said.

The article notes the 737-MAX is still grounded in China.

Full article. (https://www.wsj.com/articles/china-eastern-resumes-flights-of-boeing-737-model-involved-in-crash-11650260417?mod=hp_lista_pos3)

[WideScreen]

Checking further, today:
B-209L did do a test flight on 16/4 and a commercial return leg on 17/4.
B-209M did do a test flight on 17/4 and a commercial return leg on 18/4.

All the rest still grounded, with 4-5 B737-800 scheduled to fly on 19/4.

So, "slowly" "ungrounding".

[WideScreen]

Same with Rueters:

Given the minimal differences between a 737-700 and -800, the grounding of only the -800 fleet was more symbolic than any real concern over the airworthiness of the 737-800 fleet.
Yep, that is/was my surprise too. Indeed, maybe symbolic, or just a way to "claim" damage from Boeing, in case the accident turns out to be something with the airplane.

You're the Boeing expert: What are the differences between the B737-700 and B737-800 ? The length, the wiring around the extension locations. More ?

[Lonewolf_50]

What are the differences between the B737-700 and B737-800 ? The length, the wiring around the extension locations. More ? You may find this useful as a starting point. (https://www.aviatorjoe.net/go/compare/737-800/737-700/)

[DaveReidUK]

Or Chris Brady's superlative Boeing 737 Technical Site (http://www.b737.org.uk/).

[Arrowhead]

Pure speculation... cockpit crew member suicide.

Evidence: (i) lack of updates/general silence by CAAC, (ii) CES has put B738s back in service now (but took ages with Max's), (iii) Shenzhen stock market has tumbled 30% (and most Chinese investors borrow to invest in stocks), (iv) Evergrande and Chinese property generally bankrupt, (v) no alert to ATC of any kind despite 3 pilots normally in cockpit in China, (vi) extreme pitch, (vii) little evidence of gradual disintegration of control/fight back, (viii) rumors of FO suicide denied already by Wu Shijie, (ix) below ICAO standard flight time/rest limitations, and general management disinterest in mental health, in mainland China (x) general high level of safety and maintenance in China (ie doubtful maintenance problem, and B738 already proven), (xi) time of day of crash/weather - since most aircraft accidents are very early morning flights, or during the night, and/or in foul weather, (xii) punishment (not support and self-improvement) culture in mainland China, coupled with crazy experienced FO still in right seat

If I'm right, expect a cover up. The above are mostly China-specific problems. They cant blame it on the aircraft (for public confidence reasons), so they will have to declare no conclusions due recorders broken. Meanwhile there would be a very quiet edict from the CAAC to check the mental health of pilots (which probably wouldnt then happen) and perhaps a change to meet ICAO FTLs.

[spornrad]

https://news.cgtn.com/news/2022-04-11/Chinese-authorities-stepping-up-probe-into-plane-crash-major-risks-199bs3dRjmo/index.html
A week ago the Ch news were already mentioning
"the Civil Aviation Administration of China said... it was vital that more emphasis is placed on assessing the psychological status of air crews."
Pretty clear statement as to the cause of this crash imho.

[tdracer]

You're the Boeing expert: What are the differences between the B737-700 and B737-800 ? The length, the wiring around the extension locations. More ?

I'm not really an expert on the 737 (spent minimal time working it), but if you look at the 737NG, the -600, -700, -800, and -900, the systems and flight controls are nearly identical (aside from different wiring and control cable lengths). Similarly, engine wise, pretty much everything under the wing is the same aside from the engine rating plug. There are obviously structural differences with the different fuselage lengths and the different gross weights. The wing areas are common, although again structural differences for the different weights (mainly different thickness of the various materials). There is also some sort of structural difference going between the -700 and -800 wings - I don't know details, but when they started adding winglets they had to make minimal changes to the -800 (and -900) wings, much more major changes to the -700 wings (not sure if they ever put winglets on the -600 - not many were ever built).

[andrasz]

There is also some sort of structural difference going between the -700 and -800 wings - I don't know details...

This is not a difference between the -700/-800, it goes across the range. Boeing introduced blended winglets for NGs as BFE for -700 upwards (not the -600) sometime in the late 2000s, from thereon all aircraft coming off the line had a provisioned wing which allowed rapid installation (2 days as opposed to 3/4 days on a non-provsioned wing). Many more -700 were built before this modification, effective from L/N 1545 on the -700 and L/N 778 on the -800.

[DraggieDriver]

You're the Boeing expert: What are the differences between the B737-700 and B737-800 ? The length, the wiring around the extension locations. More ?

This article indicates B737-700 IGW would have several features of the -800, "will use a 737-700 fuselage, combined with the strengthened wing, centre body and landing gear of the larger -800."
https://www.flightglobal.com/boeing-to-offer-igw-versions-of-737-700-next-year/18470.article

[tdracer]

This is not a difference between the -700/-800, it goes across the range. Boeing introduced blended winglets for NGs as BFE for -700 upwards (not the -600) sometime in the late 2000s, from thereon all aircraft coming off the line had a provisioned wing which allowed rapid installation (2 days as opposed to 3/4 days on a non-provsioned wing). Many more -700 were built before this modification, effective from L/N 1545 on the -700 and L/N 778 on the -800.
Again, I don't know details, but what I remember is that it was much cheaper and easier to retrofit the -800 with the blended winglets than it was the -700 due to 'structural differences'. I assumed that meant more than just gage thicknesses, but I could be wrong.
Then again, it must not have been that much more difficult, since I rarely see any 737NG without winglets.

[A0283]

@tdracer - Saving a claimed few percent WITH winglets does makes things 'easy' ... doesn't it

[172_driver]

It's been a while now but I seem to remember a speed restriction for max speedbrake on some of our -700s that had been retrofitted with winglets, but not on all of them.

[PPRuNe Towers]

In mixed fleets it's alway important to know if a 700 is referred to as a hard wing or soft wing. Slang but effective differential especially for emergency descents. Learned that flying BBJ's where all airframes were wingletted.

Rob

[tdracer]

In mixed fleets it's alway important to know if a 700 is referred to as a hard wing or soft wing. Slang but effective differential especially for emergency descents. Learned that flying BBJ's where all airframes were wingletted.

Rob
IIRC, all the purpose built 737-700 BBJs had the 737-800 wing (for higher gross weight/more fuel for longer range). I suspect that's what would be the 'hard wing'. If someone converted a regular 737-700 into a BBJ, then it would still have the normal -700 wing.

[FlightDetent]

The preliminary report is out, referenced here: 关于“3•21”东航MU5735航空器飞行事故调查初步报告的情况通报 (variflight.com) (https://yenei.variflight.com/club/item/?id=3xcsz6lzz6xKddd256026b)

To my understanding, it does not discuss any causes at the moment, only declares the established facts that were debated here in much detail.

useful online translators:
百度翻译-200种语言互译、沟通全世界！ (baidu.com) (https://fanyi.baidu.com/#zh/en/)
https://translate.google.com/
https://www.deepl.com/translator
https://www.bing.com/translator

Be vigilant, sometimes the negative "not" can go missing without a warning.

[Tokyo Geoff]

???3?21???MU5735?????????????????? (http://www.caac.gov.cn/XXGK/XXGK/TZTG/202204/t20220420_212895.html)

Use Google Chrome to get a passable translation into English.

Most interesting parts

- The trailing edge of the right wingtip winglet was found approximately 12 kilometres 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

- the qualifications of the flight crew, cabin crew and maintenance release personnel meet the requirements; the airworthiness certificate of the aircraft in the accident is valid; There is no fault report and no fault reservation before the flight and short-term parking on the same day; there is no cargo declared as dangerous goods on the plane; the navigation and monitoring facilities and equipment along the route involved in this flight are not abnormal, and there is no dangerous weather forecast

-the radio communication and control command between the crew and the air traffic control department were not abnormal, and 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 restoration and analysis work is still in progress .

[Less Hair]

"No anomalies before they left the cruising altitude". How about afterwards? And how about showing the FDR readings?

[FlightDetent]

　　On 21 March 2022, Boeing 737-800 B-1791 of Eastern Airlines Yunnan Company Limited, on flight MU5735 from Kunming to Guangzhou, was cruising in the Guangzhou control area when it descended rapidly from a cruising altitude of 8,900m and eventually crashed near Mo Pai Village, Puanan Town, Wuzhou County, Guangxi Zhuang Autonomous Region. The aircraft disintegrated after hitting the ground, killing all 123 passengers and 9 crew members on board.

　　According to the Convention on International Civil Aviation, within 30 days of the date of the accident, the State organising the investigation is required to send a preliminary report to ICAO and the participating States, usually containing factual information currently available, excluding an analysis of the cause of the accident and conclusions. The preliminary report on the investigation of the MU5735 flight accident has been completed, which mainly includes information on the flight, crew, airworthiness and maintenance, wreckage distribution and other facts. The main facts are as follows.

　　The aircraft took off from Runway 21 of Kunming Changshui Airport at 13:16 BST, rose to a cruising altitude of 8900m at 13:27, entered the Guangzhou control area at 14:17 along the A599 route, and at 14:20:55 the Guangzhou regional control radar showed a "deviation from command altitude" warning. At 14:21:40, the radar last recorded the following information: standard pressure altitude 3380m, ground speed 1010km/h, heading 117 degrees. The radar signal then disappeared.

　　The accident site is located in a southeast to northwest trending valley near Mo Pai Village, Puanan Town, Wuzhou City, Guangxi Zhuang Autonomous Region. A puddle with an area of about 45 square metres and a depth of 2.7 metres was visible at the scene, which was determined to be the main impact point at 23°19′25.52″N, 111°06′44.30″E. Debris from the wreckage was found mainly on the surface and underground within a bearing of 0° to 150° from the impact site. The trailing edge of the right wingtiplet was found approximately 12km from the main impact point. There were signs of overfiring of the mountain vegetation at the accident site. Major wreckage was found at the site, including horizontal stabilisation surfaces, vertical tail, rudder, left and right engines, left and right wings, fuselage components, landing gear and cockpit interior parts. All wreckage was searched and collected from the scene and transferred to a dedicated warehouse for cleaning and identification, and placed in correspondence with the actual size and position of the aircraft to facilitate subsequent inspection and analysis.

　　After investigation, the qualifications of the flight crew, cabin crew and maintenance and release personnel on duty met the requirements; the airworthiness certificate of the aircraft involved in the accident was valid, the last A-check (31A) and the last C-check (3C) of the aircraft did not exceed the inspection time limit specified in the maintenance programme; no faults were reported before the flight and short stop and release on that day, and no faults were retained; there was no cargo declared as dangerous goods on board; the navigation and surveillance facilities and equipment along the route involved in the flight were not abnormal. There were no abnormalities in the navigation and surveillance facilities and equipment along the route involved in the flight, and no dangerous weather forecast; before deviating from the cruise altitude, there were no abnormalities in the radio communication and control command between the crew and the air traffic control department, and the last normal land-to-air call was made at 14:16; the two recorders on board were severely damaged due to the impact, and the data repair and analysis work is still in progress.

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

Translated with www.DeepL.com/Translator (free version) From Tokyo Geoff's link, the announcement on CAAC website (not the report itself though)

[A0283]

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.

end of translation

—/—
So a factual preliminary report as might be expected according to SOP.

Pity if they don’t publish an English version, that would limit translation errors, as pointed out above. Every languages has its specific complexities and ordinary and technical language in cases like these add to that.

No early AD’s or other statements.
At this stage, as you would expect, using a 2D layout for reference.
Damage to the recorders appears more severe than expected. IIRC one was found on the surface and the other about 2 m deep, the ‘can’ memory containers seemed quite good but had folded edges at one side, so maybe water entered the cans.

[averow]

Perhaps this is the only concrete information that the Chinese have so far, derived only from radar observations of the flight and the FDR and CVR have not been read (or able to be read) so far. Just speculation on my part.

[andrasz]

Again, I don't know details, but what I remember is that it was much cheaper and easier to retrofit the -800 with the blended winglets than it was the -700 due to 'structural differences'.

I presume the issue must have been that the affected -800s were already built with the provisioned wing, while the -700s were the pre-modification unprovisioned wings. According to the winglet manufacturer 300 man-hours needed for a provisioned wing, 850-1200 for an unprovisioned wing.

[PJ2]

(from the translated report): . . 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.
Well, we'll see what "restored" really means.

[DaveReidUK]

at 14:20:55 Guangzhou area control radar showed a "deviation" Command altitude" warning, the aircraft left the cruise altitude

Interesting terminology (with allowances for Google auto-translate).

The phrase "deviation command altitude" sounds like a reference to Selected Altitude - a parameter that is increasingly available to ATC in many (most?) parts of the world via Mode S/EHS, intended to allow controllers to pick up discrepancies between selected FL and cleared FL.

[andrasz]

The phrase "deviation command altitude" sounds like a reference to Selected Altitude - a parameter that is increasingly available to ATC in many (most?) parts of the world via Mode S/EHS, intended to allow controllers to pick up discrepancies between selected FL and cleared FL.
I think this is just a translation issue, commanded should be understood as cleared. In China (and ex-USSR, etc.) ATC "commands" a/c to do this or that.

[Sailvi767]

The report now confirms the part discovered 12km away is the "trailing edge of the right winglet"

Winglets are highly susceptible to flutter. A 737-800 at cruise is already near VNE. A pushover would quickly result in putting the winglets into the flutter zone and separation from the aircraft. Flutter is primarily a TAS issue and it doesn’t take much speed increase at altitude to exceed VNE. Most aircraft with retrofit winglets have their VNE reduced for this reason. With high altitude winds the distance is very plausible.

[Fursty Ferret]

Flutter is primarily a TAS issue and it doesn’t take much speed increase at altitude to exceed VNE.

A useful point and something that I get the impression is rarely understood (having had to intervene from the back seat as a passenger in a light twin when the pilot decided to do a descent at VNE into Phoenix with a 45C OAT).

[john_tullamarine]

the pilot decided to do a descent at VNE

Why on earth would anyone want to do a VNE descent ?

[Ab Initio]

Headline: "No abnormalities yet discovered..."

"According to information disclosed by the CAAC, the exterior of the flight recorder was seriously damaged and the storage units also had a certain degree of damage. But the device remained in relatively good shape.

"It takes time to decode the flight recorder. If the storage units were damaged, it may take longer. After decoding the device, it will provide strong evidence as to the cause of the accident," said Zhu Tao, head of aviation safety for the CAAC, at an earlier news conference."

[fdr]

Winglets are highly susceptible to flutter. A 737-800 at cruise is already near VNE. A pushover would quickly result in putting the winglets into the flutter zone and separation from the aircraft. Flutter is primarily a TAS issue and it doesn’t take much speed increase at altitude to exceed VNE. Most aircraft with retrofit winglets have their VNE reduced for this reason. With high altitude winds the distance is very plausible.

Concur, with caveat. The winglet (in fact all winglets) reduces the flutter boundary of a wing. The B737 took additional mass addition and stiffening in order to get a stable Nyquist plot of the system to a perturbation. The chance that there was a problem with the winglet that caused the upset is remote, the flutter of a winglet is much more likely to be a resultant symptom of an overspeed of the aircraft in an upset, or an overspeed by some other unknown cause. The plane jane wing doesn't have any particular issue with flutter. The older wings of the stumpy classics are not bad at all. Any wing if pushed enough will have an aeroelastic issue at some point. One B734 splash showed that the abuse of the boundary of the design was so severe that there was evidence of roll control reversal, which was adding to the disastrous condition the drivers got themselves into. On the day of this accident, there was some isolated buildups in a line E-W around Guangzhou- Xiamen, and there was moderate jetstreams to the north by recollection. Flutter often gives an interstitial tear failure in a composite when it finally lets loose, which was what the winglet looked like having from the start.

AFAICS, there are not any obvious situations that come to mind that a winglet that would cause a flutter event within the normal envelope of the aircraft, assuming the structure did not have a history for structural damage and a poorly conducted repair...

Caveat: The effect of a winglet is well established as far as aeroelastic effects go. TBC was aware of the effect on the early wing structure as was APB, and the structure was amended to restore the boundary to a reasonable margin. The approved envelope was also amended (by memory, a while ago) and TBC had separately published a pretty good AERO article on the subject. The aircraft meets the certification requirements and the operational boundary was set as a result. There is no "safety" issue related to having winglets that are correctly designed and certified. That flutter likely occurred indicates that the envelope was either exceeded severely, or the structure had an issue that lowered the flutter boundary, which would be something like undetected damage or am inadequate repair of known damage.


Boeing AERO 17 BLENDED WINGLETS (https://www.boeing.com/commercial/aeromagazine/aero_17/winglet_story.html)

[Gary Brown]

Apologies if this has already been cited, but Xinhua (the official Chinese State Press Agency) has put out a press release that I believe is an accurate and complete English-language version of the Mandarin-only Prelimary Report.

Press release - https://english.news.cn/20220420/b3e5c79712c24b4797cc7c17f4da45dc/c.html

Original Mandarin CAAC Prelim Report - http://www.caac.gov.cn/XXGK/XXGK/TZTG/202204/t20220420_212895.html

Nothing added - but better than Google Translate, I think!

[gearlever]

Apologies if this has already been cited, but Xinhua (the official Chinese State Press Agency) has put out a press release that I believe is an accurate and complete English-language version of the Mandarin-only Prelimary Report.

Press release - https://english.news.cn/20220420/b3e5c79712c24b4797cc7c17f4da45dc/c.html

Original Mandarin CAAC Prelim Report - ???3?21???MU5735?????????????????? (http://www.caac.gov.cn/XXGK/XXGK/TZTG/202204/t20220420_212895.html)

Nothing added - but better than Google Translate, I think!

Interesting, the horizontal stabiliser is not mentioned.

On AvHerald it is....

On Apr 20th 2022 the CAAC released a statement indicating, the preliminary report has been submitted to ICAO. The data restoration of the data of CVR and FDR is still in progress. The aircraft left assigned cruise altitude of 8900 meters at 14:20:55L. At 14:21:40L radar recorded the last position at 3380 meters altitude, speed over ground at 1010 kph at a heading of 117 degrees, the radar signal was lost at that point. The main wreckage was found in a puddle of 45 square meters and a depth of 2.7 meters at position N23.3238 E111.1123 and included horizontal stabilier, vertical tail, left and right engines, left and right wings, fuselage parts, cockpit parts as well as landing gear. Those recovered parts were transported to a warehouse for further analysis. Traces of fire were in the forest surrounding the crash site. The trailing edge of the right winglet was recovered about 12km from the main impact site. Flight and Cabin Crew qualification and certification was without flaw, the aircraft was airworthy with no deferred entries in the tech log, there was no hazardeous cargo on board. Ground based navigation facilities all operated normally, no dangerous weather was forecast for the area when the aircraft departed its cruising altitude. Radio communication with the aircraft was normal until 14:16L (the last radio communication).

[FlightDetent]

Original Mandarin CAAC Prelim Report - ???3?21???MU5735?????????????????? (http://www.caac.gov.cn/XXGK/XXGK/TZTG/202204/t20220420_212895.html) This looks the same as post 437. Which is a press release not the report itself, which is said to be 'sent to ICAO'.
​​​​​
​​​​

[Gary Brown]

This looks the same as post 437. Which is a press release not the report itself, which is said to be 'sent to ICAO'.
​​​​​
​​​​

Apologies - it is indeed the press release concerning the report sent - as per regs - to ICAO. Though the prerss release does contain a summary of findings so far, there's no obligation for the Chinese to publish the actual submitted report, and ICAO can only do so if the submitting power asks.

It is a tad odd that the Madarin and English press release summaries of the report have some small but significant differences (which I had not spotted!). My sense of course would be that the Mandarin is the better version, and the AV Herald summary of the that report is (so far as I can tell) pretty accurate as to its contents. Either the "official" English version is simply slightly incorrect (which, even in China, is not unknown!) or we must await news of any significance in the differences.

[A0283]

@gearlever - “Interesting, the horizontal stabiliser is not mentioned. On AvHerald it is....”

Finding the horizontal stabiliser was reported, first by journalists on-site and then by officials involved in the investigation, from early on and repeated since.

[fdr]

For the impact that occurred here, it is not surprising that the horizontal stab was identified in the wreckage. It will have less fragmentation than the forward parts of the aircraft. The wings would have substantial fragmentation, but inner span sections of the spar will be identifiable, The engine cores (shafts, gears, not necessarily aux cases) actuators, control, gear, flap drives etc, would be usually in identifiable components, the further back in the structure the less fragmentation of associated quadrants/cranks etc.

The presence of the stabilizer doesn't rule out some control issues, but it still remains a remote possibility for initiating events. Had parts of the stab been found 12km away it would be a point of interest, but absent that it is not indicative of cause. Even if found 12km away, the failure mode would be of significance, as would be the trajectory analysis of the part to determine when it would have separated. Controls are not indicating a factor as yet other than the obvious fact that the plane didn't get to its destination, so presumably, at some point, the flight path was not as desired, or not.

[A-3TWENTY]

I don't know what was the cause of the accident. What I DO know is the Chineses already know the cause of the accident, for two reasons:

1.I flew 10 years in China until the pandemic came, and, I know that all airplanes in China continually download both CVR and FDR through out the flight and send it to the cloud. They then keep it for 3 month. So, the bulls..t that the "black boxes"are severely damaged is just an excuse to not spread the real causes of this accident.
I had a small incident during the taxi departing for an 8 hour flight. By the time I landed (8 hours afterwards) they already had both fdr and cvr data in hands.

2. IF they had any doubt it was a plane failure , they would never have put the 738 back in service again.

[DaveReidUK]

I know that all airplanes in China continually download both CVR and FDR through out the flight and send it to the cloud.

Assuming that's true, why don't all airlines/countries do that? It would avoid some of the recent situations where there was fear that a recorder might not be found following an accident.

Do all the Boeings and Airbuses flying in China have custom modifications that allow them to stream CVR/FDR data?

[43Inches]

All this conspiracy about the Chinese release of the FDR/CVR findings when both are in Washington (have been for weeks) being analysed by the US. As for streamed CVR/FDR, yeah good one.... pretty good evidence that you may have no idea what FOQA /FDM or ACARS is.

[FlightDetent]

Assuming that's true, why don't all airlines/countries do that?After the MAS disappearance which has become a bit of a 'landing on the moon' conspiracy event in E Asia, PRC implemented 4D/15 mandate.
4D is the position and 15 min s the maximum or target reporting latency. For the 737 class and above, sure all B-reg have it, national security matters. Airborne connectivity is not a problem, definitely not on widebodies.

QCVR is also a fact since around 2019 at the latest. During the various Safety Warfare Weeks (=bonus punishment periods) the culprits breaching sterile flight deck with chatter would be named and shamed with an internal memo, for instance.

Wireless QARs (LTE modems) have been the standard on Airbii for at least 10 years. The units I was familiar then with had 3 SIM card slots BTW.

The story above may have a more trivial explanation if the taxi mixup was in China. Viewed as a breach of an ATC command this lands the pilot in very hot water. It's not beyond imagination the report from ATC reached the company and the 8 hours of elapsed time was used to plan exactly what to do. After landing the standard LTE WQAR+CVR sent the data to the mothership and decision was reached swiftly, especially with a foreigner pilot to blame.. ATC supplying their audio inside the given time frame is also very feasible.


Having said that, linking the DMU to the SATCOM communication channel does only need technology that is presently available. Pulling larger data on request can also be done, on top of the regular 4D/15. Still, indicriminate streaming broadcast is not realistic, from my point of view. This comes back to the crash discussed, data is in the US and the rest ADS-B is public domain. Probably nothing in between.

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[A-3TWENTY]

After the MAS disappearance which has become a bit of a 'landing on the moon' conspiracy event in E Asia, PRC implemented 4D/15 mandate.
4D is the position and 15 min s the maximum or target reporting latency. For the 737 class and above, sure all B-reg have it, national security matters. Airborne connectivity is not a problem, definitely not on widebodies.

QCVR is also a fact since around 2019 at the latest. During the various Safety Warfare Weeks (=bonus punishment periods) the culprits breaching sterile flight deck with chatter would be named and shamed with an internal memo, for instance.

Wireless QARs (LTE modems) have been the standard on Airbii for at least 10 years. The units I was familiar then with had 3 SIM card slots BTW.

The story above may have a more trivial explanation if the taxi mixup was in China. Viewed as a breach of an ATC command this lands the pilot in very hot water. It's not beyond imagination the report from ATC reached the company and the 8 hours of elapsed time was used to plan exactly what to do. After landing the standard LTE WQAR+CVR sent the data to the mothership and decision was reached swiftly, especially with a foreigner pilot to blame.. ATC supplying their audio inside the given time frame is also very feasible.


Having said that, linking the DMU to the SATCOM communication channel does only need technology that is presently available. Pulling larger data on request can also be done, on top of the regular 4D/15. Still, indicriminate streaming broadcast is not realistic, from my point of view. This comes back to the crash discussed, data is in the US and the rest ADS-B is public domain. Probably nothing in between.

​​​​

The incident I had was in Australia. Australia authorities called the company during the flight and when I landed in China 8 hours afterwards , the quality control already had the transcription of the CVR. THE DAY AFTER,I was there listening to my voice and the FO's. Just reminding that according to the manual, the CVR records the last 120 minutes. Not in China. In this case it was good, because thanks to that, I was considered not guilty :)

[FlightDetent]

Thanks for the details, one piece of info actually is a bit of a surprise.

Not about technology though.

[menphix]

I checked a couple local news sources, it seems that at least some Chinese airlines have started to use a system called "X-CVR", which can record up to 8000hrs of cockpit voice recordings with "quality higher than MP3".
It has also been suggested that the so-called X-CVR system supports downloading the recordings directly to USB drive, and can even transmit the recordings via 3G/4G wireless network automatically to specific servers.
Reports say Hainan Airlines has started to fit its 737 and A320 fleets with X-CVR as early as 2018. So it looks like such technology already exists in China, although it's unclear whether MU has started to fit their 737s with the system.

[DaveReidUK]

I checked a couple local news sources, it seems that at least some Chinese airlines have started to use a system called "X-CVR", which can record up to 8000hrs of cockpit voice recordings with "quality higher than MP3".
It has also been suggested that the so-called X-CVR system supports downloading the recordings directly to USB drive, and can even transmit the recordings via 3G/4G wireless network automatically to specific servers.
Reports say Hainan Airlines has started to fit its 737 and A320 fleets with X-CVR as early as 2018. So it looks like such technology already exists in China, although it's unclear whether MU has started to fit their 737s with the system.

We've already been told that all Chinese airlines are already continuously streaming FDR and CVR data - is that not the case ?

[FlightDetent]

We've already been told that all Chinese airlines are already continuously streaming FDR and CVR data - is that not the case ? Regardless of once or twice, it is not the case. :-) And the anecdotal evidence has a technological explanation without broadcast streaming....

[JeroenD]

I
It has also been suggested that the so-called X-CVR system supports downloading the recordings directly to USB drive, and can even transmit the recordings via 3G/4G wireless network automatically to specific servers.


Mobile networks system are dimensioned and designed to provide maximum coverage and capacity on land, not in the air. The antenna are orientated at an angle downwards. (Not necessarily the physical antenna, that might be vertical, but it will transmit downward).

At a typical cruising altitude you won’t have any coverage. Even at much lower cruising altitudes, the coverage would be patchy and handovers (when you move from one cell to the next) can be troublesome. So I doubt 3G/4G or any G for that matter has the capability to provide continues streaming capabilities for planes. It doesn’t do so, when I fly my little single prop planes at much lower altitudes.

Jeroen

[A0283]

just thinking …

If you record while airborne and store while airborne, then you could start to transfer that data from a position that puts you in reach of the ground station.

From the ground station you can then distribute it over higher volume networks.

That would make it possible to have data for analysis before the plane arrives at the gate.

So precise language is needed here … is it continuous any altitude air to ground streaming… or batch/burst when in reach…

the functionality is similar but the performance quite different… bandwidth and range …

the crash area is quite remote and rough by the way and even the SAR had Comms issues …
so even a working batch system would have had coverage issues,

[BuzzBox]

We've already been told that all Chinese airlines are already continuously streaming FDR and CVR data - is that not the case ?

Not streamed, but easily downloadable by 4G as soon as the aircraft is on the ground:
QACVR Solution-DONICA (http://www.donica.com/en/assistance/20.html)

It’s little wonder that China has a reputation as a ‘surveillance State’. 🙄

Perhaps in-flight 4G is also possible:
IN-FLIGHT BROADBAND REACHES NEW HIGHS WITH 4G SOLUTION FROM THALES (https://www.thalesgroup.com/en/group/journalist/press-release/flight-broadband-reaches-new-highs-4g-solution-thales-uk-nokia-and)

[ATC Watcher]

DONICA stuff : very interesting , especially this part :
helping to provide evidence for the safety investigation pilot evaluation and responsibility partition.
Totally against the spirit of ICAO incident investigations . and if I read correctly it goes far beyond 3 hours and the CB cannot be pulled on that one ..
I guess the video camera will be next..

[BuzzBox]

Totally against the spirit of ICAO incident investigations . and if I read correctly it goes far beyond 3 hours and the CB cannot be pulled on that one ..
I guess the video camera will be next..

Absolutely. Too easily abused, especially in that country.

I wonder what their unions had to say about it. LOL 🤣

[CBD3000]

If I, as slf, can us the free wifi on QANTAS flights to send text and much larger image files then why is it difficult to send CVR and FDR info back to base?

[BuzzBox]

If I, as slf, can us the free wifi on QANTAS flights to send text and much larger image files then why is it difficult to send CVR and FDR info back to base?

I think there are two major reasons. First, there simply isn't enough bandwidth available using 'traditional' systems such as VHF datalink and SATCOM. CVRs and FDRs generate a huge volume of data and when you multiply that by the large number of aircraft that might be airborne in the same area at the same time, the available bandwidth isn't sufficient to reliably support data streaming. Second, is cost. Data streaming is expensive and nobody's been able to justify the extra cost on safety grounds. That said, technology is constantly changing and there will no doubt come a time when streaming of CVR and FDR becomes feasible. Mind you, international regulatory change normally take years so it will no doubt be a long time before data streaming becomes the 'norm'.

[hijack]

XCVR technology long implemented in China Eastern. This XCVR with certain software, can detects words that are sensitive to managements.
I do not think the CAAC will review the information on the CVR. Face reason they would rather damage it and sent it back to boeing for the analysis.
They will come up with a story like unlawful interference rather what was speculated previously. Sorry for all. I know this is disappointing but this is how it works in china.

[m0nkfish]

I think there are two major reasons. First, there simply isn't enough bandwidth available using 'traditional' systems such as VHF datalink and SATCOM. CVRs and FDRs generate a huge volume of data and when you multiply that by the large number of aircraft that might be airborne in the same area at the same time, the available bandwidth isn't sufficient to reliably support data streaming. Second, is cost. Data streaming is expensive and nobody's been able to justify the extra cost on safety grounds. That said, technology is constantly changing and there will no doubt come a time when streaming of CVR and FDR becomes feasible. Mind you, international regulatory change normally take years so it will no doubt be a long time before data streaming becomes the 'norm'.

I'm not an expert on satellite communications but would be interested to hear from anyone that is. Do the SATCOM packages installed on civilian aircraft require the antenna to be aligned with an appropriate satellite? If so, it is likely that any uplink is going to be terminated at the point where you are going to most want the data from the FDR/CVR when the aircraft departs from controlled flight (assuming there is such a departure).

[WideScreen]

I'm not an expert on satellite communications but would be interested to hear from anyone that is. Do the SATCOM packages installed on civilian aircraft require the antenna to be aligned with an appropriate satellite? If so, it is likely that any uplink is going to be terminated at the point where you are going to most want the data from the FDR/CVR when the aircraft departs from controlled flight (assuming there is such a departure).
Aligning: Yep. Though usually, the reason of an upset is before the upset itself happens.

Regarding the spying out on Pilots: I don't think, this data goes into the regular CVR/FDR, though more into a QAR type, which probably won't survive a crash like MU5735. Though useful, to "control" the political thinking of pilots, ehhhh, to enhance safety to correct pilot errors before these can become an issue.

[Lake1952]

I'm not an expert on satellite communications but would be interested to hear from anyone that is. Do the SATCOM packages installed on civilian aircraft require the antenna to be aligned with an appropriate satellite? If so, it is likely that any uplink is going to be terminated at the point where you are going to most want the data from the FDR/CVR when the aircraft departs from controlled flight (assuming there is such a departure).

Well, as a passenger, I certainly lose satellite TV reception frequently at modest bank angles.

[txl]

Slight detour: In-flight internet isn't done by satellite only. There are newer technologies available that connect an aircraft at cruise altitude to LTE networks on the ground using special upward pointing antennas that cover a radius of about 150km. That obviously works over land only, but delivers decent enough throughput. Aircraft antennas are being installed on the bottom of the fuselage. Much cheaper also for airlines. If you're interested in the details, google "Nokia A2G" for example. The system has been rolled out throughout most of Europe (European Aviation Network (https://www.europeanaviationnetwork.com/en/index.html)/EAN), I don't know about China. But Chinese companies are leading in mobile network tech, so I'd presume they have something like that.

[n5296s]

Do the SATCOM packages installed on civilian aircraft require the antenna to be aligned with an appropriate satellite?
Short answer: yes

Longer answer: and it isn't easy. I worked with a company that does the satellite internet connection for a major US operator, and saw the antenna system with the covers off. The antenna itself is about a metre long and 10cm square. It is attached to a serious dual-gymbal positioning system which can whizz it around at great speed - it is dangerous to be close to it when it is running. iirc it can pull up to about 100A in turbulence. There is however an assumption that it will be on the top surface of the aircraft, not the bottom or the side.

[jfill]

I think recent aircraft use phased array solid state antennas with no moving parts. Its the long thin bulge on the top of the aircraft.

[Carbon Bootprint]

Flight data indicates someone in the cockpit intentionally crashed a China Eastern (https://www.wsj.com/market-data/quotes/CEA) jet earlier this year, according to people familiar with U.S. officials’ preliminary assessment of what led to the accident.

The Boeing 737-800 was cruising at high altitude when it suddenly pitched into a near-vertical descent, plummeting into a mountain at extreme speed. Data from a black box recovered in the crash suggests inputs to the controls pushed the plane into the fatal dive, these people said.

“The plane did what it was told to do by someone in the cockpit,” said a person who is familiar with American officials’ preliminary assessment, which includes an analysis of information extracted from the plane’s damaged flight-data recorder.

Also underpinning the American officials’ assessment, this person said: Chinese authorities, who are leading the investigation, so far haven’t flagged any mechanical or flight-control problems with the plane involved in the March 21 crash in southern China (https://www.wsj.com/articles/china-plane-crash-what-to-know-about-boeing-flight-11647884381?mod=article_inline). That model is a workhorse of the global aviation industry and is part of a family of Boeing aircraft that have one of the best safety records in commercial flying.

Source article here (https://www.wsj.com/articles/china-eastern-black-box-points-to-intentional-nosedive-11652805097).

[Peristatos]

https://nypost.com/2022/05/17/black-box-on-china-eastern-flight-indicates-intentional-act/
Black box on doomed China Eastern flight indicates crash was intentional: report

[krismiler]

The authorities will now be very concerned with the issue of pilot's mental health if this is true. After the Germanwings crash seven years ago, and a few before that which were suspected but not proven, something needs to be done.

Possibly we're going back to the days of not being left alone in the flight deck again. A psychiatric evaluation could be added to our medicals alongside the usual ECG, audiogram etc.

[pattern_is_full]

Possibly we're going back to the days of not being left alone in the flight deck again.

Is that relevant in this case? I thought there were two other pilots in the China Eastern cockpit at the time, and it apparently made no difference.

[das Uber Soldat]

Possibly we're going back to the days of not being left alone in the flight deck again. A psychiatric evaluation could be added to our medicals alongside the usual ECG, audiogram etc.
How does that help? All you're doing is introducing yet another potentially mentally unwell person into the flight deck, standing right behind the seated pilot and next to the crash axe. There is a reason the requirement lasted less than a year, even at Germanwings.

[WideScreen]

For now, the description is still vague and does not trace 1:1 back to a deliberate pilot (or someone else's) action.

The description suggests, it was a nose-down happening, so a pitch issue and no aileron input or engine failure or so.

The description doesn't say, whether this is a control column or trim happening.

A deliberate pilot action would not so much match with a control regain, halfway down and subsequently again a nose-down movement. Nor would a deliberate action match with the obvious attempt to "keep the airplane on course".

Strange thing is, we only do hear about the FDR results and not about the CVR, where the CVR might give the verbal pilot interaction, a more conclusive aspect around a deliberate action.

So, for now, the whole is far from conclusive (despite the world press jumping on the "deliberate" description).

[BoeingDriver99]

The “authorities” were very concerned seven years ago and did pretty much nothing. All psychiatric evaluations will do is create a bunch of false positives; tell a bunch of psychiatrists/psychologists to find problem pilots and they will go and find them for you. Doesn’t matter if they are the risky ones; Something Will Have Been Done. And the at risk pilots will be wise enough to *gasp* hide their problems.

The problem is rare enough that the governments/regulators/airlines/management can afford the occasional worldwide suicide/hull loss versus the worldwide cost of doing something effective about it. Key word being effective.

So anticipate some ineffective, not thought through responses that will be quietly dropped in the future at some point.

[BoeingDriver99]

WideScreen has it occurred to you that the other two pilots in the flight deck may have disagreed with the other pilot and perhaps attempted to take control?

[Jonty]

I’m not buying it.
These Boeings have a history of “deliberately” crashing. The only suicide I know of that’s been confirmed was the German Wings one. The rest are conjecture to save the manufacturer,

[SOPS]

I’m not buying it.
These Boeings have a history of “deliberately” crashing. The only suicide I know of that’s been confirmed was the German Wings one. The rest are conjecture to save the manufacturer,

Can you kindly point us to this “history” ?

[slfool]

China Eastern plane crash likely intentional, US reports say (https://www.bbc.co.uk/news/business-61488976)

[krismiler]

If we look at the number of actual or suspected suicide crashes involving just commercial flights and excluding terrorist incidents, the numbers are quite disturbing.

https://en.m.wikipedia.org/wiki/Suicide_by_pilot

A technical issue on a particular type which was causing a hull loss this frequently would be unacceptable and the fleet would be grounded until it was rectified. The authorities will need to be seen to be taking action, even if it's ineffective at least they tried something. Having a cabin crew come in when one pilot left the flight deck didn't really achieve anything. The next step could be psychiatric evaluations which enable the buck to be passed on to the psychiatrist if anything happens.
​​

[FullMetalJackass]

Let's not forget there are cultures where Pilot Suicide is considered unacceptable as a cause for a crash hence the local authorities and the airline themselves will look for a face saving alternative - blaming the plane - even though in the case of (e.g.) EgyptAir 990 it was pretty clear that the relief pilot had caused the crash.....

[Less Hair]

If not even the cockpit colleagues sitting next to him get any warning right before I doubt that a psychiatrist can give guarantees. The 4U pilot back then deliberately split up his issues and met different doctors to hide the size of his only known to him problems.
Should all mental illnesses be blocked now, including pilots having suffered only for limited periods? Just to be on the safe side?
On the other hand what does it mean for teamwork, trust and safety culture? Will this bring us the single pilot cockpit with remote surveillance and some AI-master check for "plausible" flight operations?