China Eastern MU5735 crash (Boeing 737-800)

Forums › Travel (planes, train, cruise) › China Eastern MU5735 crash (Boeing 737-800)

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#295330 22-Mar-2022 07:43

https://www.nzherald.co.nz/world/china-eastern-airlines-boeing-737-carrying-132-crashes-in-province-of-guangxi/KDMSM55DD4WAN3ROHMX7FJAY5M/

rescuers had been dispatched and there was no immediate confirmation of numbers of dead and injured.

One villager told a local news site that the plane involved in the crash had "completely fallen apart" and he had seen nearby forest areas destroyed by a fire caused when the plane crashed onto the mountainside.

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#2889861 22-Mar-2022 07:45

Also Google says it's not a MAX plane

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#2889863 22-Mar-2022 07:59

Just wondering why you posted this and what your point is. You make no personal comment and you have no query related to it - it's just a link to a news item. If it was a Max, it probably would have been worth drawing attention to it - but it's not, so what?

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#2889895 22-Mar-2022 09:40

I see a photo online where the nose of the plane is pointing pretty much at the ground and reports are it descended at 840kmph.

I am unsure what kind of malfunction could have this happen? Even with no power, a plane shouldn't do this surely?

Intentional?

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#2889898 22-Mar-2022 09:48

Bit early to say but it's not unprecedented, from memory an DC-9 went nose straight down with an elevator jackscrew issue late 90's early 2000's. One of the US airlines too and I think in the end it was a maintenance issue with greasing. At least it's not a max. Will be interesting to follow this investigation

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#2889901 22-Mar-2022 09:49

The Herald video shows in a high speed vertical dive. Wonder if the black boxes are intact..

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#2889907 22-Mar-2022 10:05

More information will emerge with the fullness of time but immediate areas of interest would be:
- were there any pilot comms with ATC prior to the crash?
- any evidence of onboard explosions that could cause a catastrophic failure ?
- was regular maintenance performed on this airframe?

I doubt that there is some flaw with the 737-800 - it’s an exceptionally well used aircraft with a good safety record.

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#2889917 22-Mar-2022 10:35

Beccara:

Bit early to say but it's not unprecedented, from memory an DC-9 went nose straight down with an elevator jackscrew issue late 90's early 2000's.

It's not unprecedented for the 737. There was a rudder issue with earlier models. Actually, this crash is already listed as a suspected rudder failure.... https://en.wikipedia.org/wiki/Boeing_737_rudder_issues

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#2889922 22-Mar-2022 10:52

The rudder problems in the 90s were related to the design of the power control unit sourced from Parker Hannifin. This has long since been resolved.

You couldn't entirely rule out this accident being a rudder malfunction but, if so, it won't be related to those previous malfunctions. I would say that this accident will almost certainly have human factors involved, but it's not helpful to speculate any further until we have more information.

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#2889927 22-Mar-2022 11:01

With the Plane with it's nose pointing almost straight at the ground, and doing an estimated 840kmph, is it being powered, or falling? I mean these plans do 840kmph level, so pointing downward I'd expect it to be much faster than that.

I am not familiar with the physics of it, but an uncontrolled fall wouldn't be nose to the ground the whole time, right? It would rotate around etc (more like tumbling)?

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#2889931 22-Mar-2022 11:09

Regardless of anything, those poor people. It would have been a terrifying unpleasant way to go.

You can only hope they were unconscious quickly and didn't suffer too much.

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#2889945 22-Mar-2022 12:02

networkn:

With the Plane with it's nose pointing almost straight at the ground, and doing an estimated 840kmph, is it being powered, or falling? I mean these plans do 840kmph level, so pointing downward I'd expect it to be much faster than that.

I am not familiar with the physics of it, but an uncontrolled fall wouldn't be nose to the ground the whole time, right? It would rotate around etc (more like tumbling)?

The reported decent rate would have exceeded the structural design limits of the aircraft, so it's highly likely that it would have suffered an in-flight breakup before it struck the ground. The exact trajectory towards the ground would depend on the nature of the breakup and the event that originally caused the upset.

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#2890004 22-Mar-2022 12:29

alasta:

The reported decent rate would have exceeded the structural design limits of the aircraft, so it's highly likely that it would have suffered an in-flight breakup before it struck the ground. The exact trajectory towards the ground would depend on the nature of the breakup and the event that originally caused the upset.

A picture in the news shows it vertical, and by witnesses. Likely to be a control failure (lost control of elevator, trim etc. If it was tumbling and rotating, unlikely to be at 850kph, and it would have broken up, but it was largely intact going by witnesses

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#2890005 22-Mar-2022 12:30

networkn:

With the Plane with it's nose pointing almost straight at the ground, and doing an estimated 840kmph, is it being powered, or falling? I mean these plans do 840kmph level, so pointing downward I'd expect it to be much faster than that.

I am not familiar with the physics of it, but an uncontrolled fall wouldn't be nose to the ground the whole time, right? It would rotate around etc (more like tumbling)?

High speeds in jets are done at high altitude... the low air density means low drag which in turn means high speed is possible. And necessary, because the low density increases the (true, as opposed to indicated) stall speed. Cruise speed of 737-800 at 35,000ft is 842kph, which is suspiciously close to the 840kph you quote. Max speed is 522 knots = 966kph. Doing these speeds at low altitude (say below 10,000ft) would overstress the airframe. Pointing down vertically, it would quickly accelerate to this and beyond, even if unpowered. Uncontrolled is unlikely... either the pilots would be in control or the autopilot would. Rotation and especially or tumbling would be quite unlikely in that scenario. If the aircraft is stalled (flown too slowly to produce enough lift) and yawed (turned with the rudder) at the same time, it can enter a spin, with a high rate of descent coupled with a high rotation rate, but with a low airspeed. This can be a stable condition... it will continue to do this if the pilot doesn't correct it. Some aircraft, depending on size and position of rudder, and centre of gravity, and other stuff, cannot be recovered from a spin, and/or the recovery may overstress the airframe. Obviously, all but aerobatic pilots avoid stalling and even moreso spinning if at all possible. Tumbling (I assume you mean some kind of end-over-end rotation) of an airliner would probably break it up, but it is also quite unlikely because the streamlined shape and tail surfaces tend to keep the aircraft moving and pointing in the same direction.

So, to answer your questions: A 737-800 with it's nose pointing almost straight at the ground would only be doing 840kph briefly -- it would be accelerating rapidly, whether powered or not. In an uncontrolled fall, you would have to ask how it came to be out of control. But generally speaking I would expect it to glide rather than fall. But if it was stalled, it could enter a spin.

[Edit, after reading and watching the video and looking at FlightRadar] "The plane's altitude dropped from 8,869 meters (29,098 feet) to 1,333.5 meters (4,375 feet) in the span of three minutes, state news agency China News Service reported, citing VariFlight, a Chinese technology company that provides civil aviation data services."

Contrary to what I read, FR shows it was quite a long way (an hour, so 800km?) into its flight before it crashed, perhaps aboutat the point where it would begin its descent for landing. It doesn't descend vertically -- it travels about 5km horizontally in the space that it descends about 6,000m, so its average path is much closer to a 45 degree descent. Nevertheless, that is abnormally steep, and I'd say that 6 or 7 thousand feet per minute is beyond the aircraft's specs. The video looks to be of an intact aircraft, rather than an in-flight breakup.

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#2890006 22-Mar-2022 12:32

Video shows it last few hundred metres before impact

https://www.stuff.co.nz/world/asia/300546618/china-eastern-airlines-plane-nosedived-at-over-840kmh-into-mountains-killing-132-people

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#2890009 22-Mar-2022 12:42

tdgeek:

Video shows it last few hundred metres before impact

https://www.stuff.co.nz/world/asia/300546618/china-eastern-airlines-plane-nosedived-at-over-840kmh-into-mountains-killing-132-people

My God that is terrifying.

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