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-   -   China Eastern 737-800 MU5735 accident March 2022 (https://www.pprune.org/rumours-news/645805-china-eastern-737-800-mu5735-accident-march-2022-a.html)

Jason74 21st Mar 2022 12:25


Originally Posted by AmuDarya (Post 11203147)
It might be helpful for the discussion here (as amateur speculations are not deleted) for professionals here to 1) state their credentials and 2) list causative factors that can be ruled out, given the extremely minimal information available.

That might help the readers here with a baseline against which these drive-by amateur comments can be measured.

Credentials:
15 years Royal Australian Air Force. Qualified on PC9, C-130, Macchi MB-326, F/A-18, Hawk-127. Qualified Flying Instructor, Instrument Rating Examiner, Low Level Demonstration Pilot, Flying Safety Officer.
15 years airline pilot. Captain on A350, A330.

Causative Factors:
Absolutely no idea. How could I offer an opinion before the data is in?


My deepest condolences to the families of those involved.

CW247 21st Mar 2022 12:29

All 737-800s at MU are grounded
My hunch is a runaway trim.

Salina Chan 21st Mar 2022 12:36


Originally Posted by CW247 (Post 11203191)
All 737-800s at MU are grounded.

says who? FR24 seems to disagree, there are about ten of their 738s in flight as of this posting

logansi 21st Mar 2022 12:51

Interesting new data in the more granular data from Flightradar24

If the reporting is correct it seems to show that for a short period the crew recovered, gained altitude before the dive resumed.

https://cimg2.ibsrv.net/gimg/pprune....4dcaf384fd.png

Cool banana 21st Mar 2022 12:53

China Eastern 737-800 MU5735 incident
 
This appears to be the lower outer wing structure, with the fuel tank blow out panels missing,

https://cimg9.ibsrv.net/gimg/pprune....2f0df2f4f7.jpg
From Weibo, Aircraft debris near the scene of the accident.

A320 Glider 21st Mar 2022 12:53

Guys, do you remember Germanwings? I stated early on in the discussion that a plane doesn't go from cruise to crash very quickly. I was immediately mobbed on here when I suggested it was suicide. Now the bells are ringing again nearly 7 years to this day (24th Mar) and again I am being mobbed for saying this looks like a suicide event.

I have been on PPRuNe a lot longer than most that say don't speculate.
I do not fly the 737 but many on here do and this will be unfortunately another learning event for us all.

It is healthy for us to have a grown up discussion regarding accidents. This is how we learn in the industry. Our checklists, procedures and everything we do are unfortunately written in the blood of our deceased colleagues.

aeromech3 21st Mar 2022 12:58

From eagle 21 picture. Well the rudder is composite and the blue ends at the trailing edge; strange how some rivets are torn through and others just popped; the aluminium non painted piece looks whole and with no external paintwork unlikely the nose of the rudder, presume could be a back closing panel of the V.fin where the nose of the rudder swings, the green bracket also that area. and so rudder flutter and delamination less likely in MHO.
JAL123 a B747 RPB repair failure leading to an over pressurisation in the tail section comes to mind, though it is unlikely to have been started in this case by a cabin air loss as blow out vents are now designed to cope with this..

A320 Glider 21st Mar 2022 13:01


Originally Posted by aeromech3 (Post 11203210)
JAL123 a B747 RPB repair failure leading to an over pressurisation in the tail section comes to mind, though it is unlikely to have been started in this case by a cabin air loss as blow out vents are now designed to cope with this..

Plus the aircraft was at cruise for quite some time.
If it was a structural failure due to pressurization, it would have occurred a lot sooner in the flight (i.e. during climb, just like JAL123 and CAL611).

henra 21st Mar 2022 13:04


Originally Posted by logansi (Post 11203205)
Interesting new data in the more granular data from Flightradar24

If the reporting is correct it seems to show that for a short period the crew recovered, gained altitude before the dive resumed.

https://cimg2.ibsrv.net/gimg/pprune....4dcaf384fd.png

Speed vs. vertical speed doesn't seem to make much sense. Maybe timing issue between the columns?

dr dre 21st Mar 2022 13:24


Originally Posted by CW247 (Post 11203191)
All 737-800s at MU are grounded
My hunch is a runaway trim.

In the 3 recent incidents of 737 runaway trim (2 MAXs and Fly Dubai at Rostov) the descent angle with the runaway nose down trim was at a max about 45 degrees. The two social media videos of this incident indicate a far greater descent angle.

Plus there was a period of erratic flight prior to the final nose down pitch and descent, this incident seems to have suffered an almost instant controlled flight in cruise to near vertical descent.

Silver Shadow 21st Mar 2022 13:49

Photos of large pieces of debris on the ground do not seem consistent with being part of the plane when it slammed into the ground. Detached prior? Location where found??

Kenny 21st Mar 2022 13:59


Originally Posted by Cool banana (Post 11203251)
A total of 132 people on board, made up with 123 passenger and 9 crew members, so at least one or both jump seats would had been occupied during the flight, that should rule out hijacking or suicide possible cause.

If you mean the cockpit jump seats must have been occupied, not all 73ís come with the second JS. 5 cabin crew and 2 pilots, might have simply meant that 2 cabin crew were in the CC jump seats.

Last time I saw a flight track like that and a vertical dive to the end, was the Alaska Airlines loss of Stab.

Hogger60 21st Mar 2022 14:07


Originally Posted by Kenny (Post 11203266)
If you mean the cockpit jump seats must have been occupied, not all 73’s come with the second JS. 5 cabin crew and 2 pilots, might have simply meant that 2 cabin crew were in the CC jump seats.

Most Chinese airlines have at least 3 or sometimes 4 pilots. I've seen many crews with Capt, FO, SO, and 1 stripe cadets walking to the airplane. So my guess is 4 pilots and 5 cabin crew.

diclemeg 21st Mar 2022 14:58


Originally Posted by rkenyon (Post 11203235)
Germanwings didn't go from cruise to crash very quickly... it was a slowish descent into the mountain. Nothing like this.

You are correct...however there was another suicide crash by a disgruntled asian pilot, that looks like this. I think it was Silk Air in Indonesia.

Christodoulidesd 21st Mar 2022 15:02

how about cut-off broken rudder like the
a310 in new york in 2001?

DoggyWoggy 21st Mar 2022 15:11

Who remembers the Air Nippon 737-700 incident where the copilot was trying to let the Captain back into the cockpit and accidentally mistook the rudder trim wheel for the cockpit door switch? The pilot ended up putting the aircraft in a 30000ft/min descent with almost full uncommanded rudder deflection.

Unfortunately I can’t post links because I’m below 10 posts but a quick Google of ANA 117 will come up with results.

tupungato 21st Mar 2022 15:11


Originally Posted by Christodoulidesd (Post 11203317)
how about cut-off broken rudder like the American Airlines Flight 587 a310 in new york in 2001?

It was A300, not A310.

EI_DVM 21st Mar 2022 15:12

A rudder hard-over and the resulting bank could likely result in these sorts of rates of descent.

Though personally my mind is quite open as to the cause at this stage.

Initially I'd speculated a deep stall, with the crew unable to get the nose down based on the initial reported VS similar to AF447, however the since revealed fairly consistent and then increasing GS seems to make this appear less likely for now as well as the cruise altitude of FL290 would have a significant margin away from coffin corner.

In my experience emergency descents even with full speed-brake in the Mach to Speed transition only tend to result in a VS of 8,000-9,000 fpm before quickly stabilising at about 4,000-5,000fpm once the transition to speed is complete which seems incompatible with this VS, particularly given the aircraft was pretty much at the MACH/Speed cross over altitude or there abouts.

Wings falling off or other structural failure seems a possibility, this should be able to be determined within the next few days should the debris of the wings or tailplane be found a distance from the main fuselage wreckage.

A suicide possibility exists, but it would have to be very drastic to get the airplane into that sort of attitude, and then the short recovery of altitude before the final dive seems to indicate there was an attempt to recover. IIRC the German Wings incident involved a much more tame 3,500-4,000fpm descent as well with no attempted recovery.

All speculation for the next while.

procede 21st Mar 2022 15:22

Could trim or pilot input get the attitude so nose down? I would think you would need a complete failure of the elevator and/or horizontal tail.


Christodoulidesd 21st Mar 2022 15:35

stand corrected sir


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