OT: 737 Max Ethiopian Crash Report

Here is a link to the complete Ethiopian preliminary crash report:
https://games-cdn.washingtonpost.com/notes/prod/default/documents/6375a995-4d9f-4543-bc1e-12666dfe2869/note/4cb6f748-a0c0-45c2-bf0b-f672ba3cfebe.pdf
The Ethiopians say that the crew followed the procedure for runaway trim/MCAS, but from their own report, that isn't clear. It shows that they identified the trim problem, the first officer indicated they should disable the electric trim and the captain agreed. It was turned off and while MCAS tried to move the nose down again shortly after that, it had no effect. After that they continue to fight with the plane, the captain asks the co-pilot if trim is working and he says no and asks if he should use manual. (that's bizarre, as all there is at that point is manual trim, so what did they think they were doing after turning off the electric?) A few secs later the co-pilot says that it's not working, but no explanation of what he meant by that. Sometime after that someone put the electric trim back on and 5 secs later MCAS shoved the nose down again, 30 secs later, it crashed.
Not answered is what the co-pilot meant by the trim wasn't working when he tried manual trim? Was he trying to move the trim wheel and it would not move? Or was he confused and really trying to use the buttons? And who turned the electric back on, without apparently any discussion? You would think these aircraft would have video recording too by now. That would help show who was doing what. One major mistake here is that one of the two pilots apparently turned the electric trim back on without discussion or informing the other pilot.
Also in that report are prior trouble reports logged, there are several prior incidents where pilots reported the plane rolling unexpectedly, strange altitude and other indicators in the cockpit that appeared briefly, etc. Another thing that would not seem to make sense is that if it's just an AOA/MCAS thing, why did the pilots airspeed differ significantly from the co-pilots for much of the flight? Leading one to wonder if the MCAS thing is all that's wrong here. the plane.
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Pilots have vehemently opposed this every time it has been suggested.
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On Fri, 5 Apr 2019 11:05:21 -0700 (PDT), trader_4

There seemed to be a lot of stuff going on there but it appears they did not know how to fly the plane manually so they took another shot at letting MCAS do it., When they turned MCAS off, they still had to manually use the trim wheel to bring the nose back up and they may not have understood how far MCAS had them out of whack. A pilot on AvWeb said that trim wheel is "laborious" to use and I assume that means a lot of spinning on the wheel gets a little change in trim. In normal flight that lets you make fine adjustments but if MCAS put max trim in, it would take a lot of wheeling to bring it back. It was admitted MCAS will put in a lot more trim that first reported. I still think better pilots would have landed that plane. Simply lowering the flaps a tiny bit would have fixed the problem, disabling MCAS but leaving electric trim on but they didn't seem to know that because Boeing never really explained how MCAS worked. None of this has hurt the stock. I guess my orders will not trade. ;-(
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wrote:

That's why you use the trim button on the yoke and only disable the electric trim once you have the trim where you want it, to stop the MCAS from trimming it nose down again.

Yes, that's what happened on the Lion Air flight before the one that crashed, the same plane.

Easy to be wise after the event.

And didn't spell out what to do in the manual either.

Yet.

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On Sat, 6 Apr 2019 11:31:17 +1100, "Rod Speed"

Short of another crash after the fix is installed, I think they live through it. The stock is climbing again, almost at $400
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wrote:

Yes, but with one hell of an impact on their reputation.

And it remains to be seen what it will do if the fix isnt approved quickly.
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On Friday, April 5, 2019 at 8:37:37 PM UTC-4, Rod Speed wrote:

While that sounds logical, it's not part of the Boeing procedure. Likely to keep it simple and when you have runaway electric trim, you don't know what caused it, what part of it is working, what isn't.

All pilots are supposed to be trained in dealing with runaway electric trim and have the very simple procedure committed to memory. The co-pilot here recognized the problem and they initially followed the correct procedure. Then two minutes later, someone turned the electric trim back on, which was a total deviation from the procedure and apparently was done without discussion and without informing the other pilot. The question is why.
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wrote:

But has the major downside that if the trim is way off, it will take a long time to get it back to where it should be if you are manually winding the trim wheels and you may well crash before you get it back to where it needs to be. Doesn’t take long to check if the trim button on the yoke still works before turning off the electric trim.

Clearly that doesn’t appear to have worked with the Ethiopian.

Presumably because it was obvious that trying to wind the trim back manual wasn’t working quickly enough.

Presumably because it was obvious that trying to wind the trim back manual wasn’t working quickly enough.
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On Saturday, April 6, 2019 at 2:34:27 PM UTC-4, Rod Speed wrote:

rim

Did I say otherwise? I said:
"While that sounds logical, it's not part of the Boeing procedure. "
And how do you know how long it takes to adjust the trim by hand? Perhaps you can show us where what you say should be, is actually part of the procedure or training for any aircraft? I haven't seen it. Only for runaway trim, turn off the electric and then trim by hand turning the wheels. That's the Boeing procedure, again probably to keep it simple and because in an emergency you don't know what in the electrical system works and what does not.

.
That's probably true. If that transcript includes everything said back and forth of any relevance, it's shocking that we don't hear back and forth about who's adjusting the trim by hand via the wheel, what the current trim position is, what it should be, etc. Also really bad that someone apparently turned the electric trim back on without discussion or announcin g they were doing it. Also, unless there is another defect we don't know about, whoever turned it on should have had their finger on the up trim button at the time. Instead, the first action after is MCAS shoving the nose down again.

That would be pure speculation. And if that's the case, again, there should have been communication back and forth about what the problem was, why it wasn't working, what needed to be done instead.
You'd expect that after the co-pilot turned off the electric there would have been discussion like:
CP - Trim disabled. Doing nose up trim using the trim wheel, what do we need to target it at?
Pilot - about X
CP, At y, turning it as fast as I can or I can't move it.
etc, etc.
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On Friday, April 5, 2019 at 7:53:39 PM UTC-4, snipped-for-privacy@aol.com wrote:

+1
We don't have the CVR because the Ethiopians won't release it, so we don't know what else was said, what the actual words were, what they said that was left out. If what's there accurately reflects what was going on, then it's clear that there was poor communication between the pilots. Like no discussion about turning the electric trim back on or even either saying that they were doing it. Also nothing about what the current trim position was and what it needed to be set to. I posted a simulator video of pilots doing the runaway trim procedure and there was constant communication back and forth. One pilot adjusted the trim wheels as needed while the other flew the plane. He was asking if the trim is OK now, does it need more, etc.

That would be my leading theory too. Unless with max trim and high enough airspeed it becomes impossible to turn the trim wheels. But that gets back to the report. The co-pilot says he's going to use manual, just 8 secs later he says it's not working, but nothing more. No, "I can't turn the wheel". I wonder if by "manual" he really meant turning the wheel by hand? Or in confusion did he mean he was going to use the trim buttons, which were now inoperative? Also, if the wheels can't be turned at max trim and high airspeed, you'd think that would be a big problem in all 737s.
Also, after one of them turned the electric trim back on, the report only shows that MCAS then pushed the nose back down. IF they were turning it back on, perhaps to move the trim quickly to where it needed to be, then one of them should have been on the trim up button as it was being turned back on. Also, why in all of this no discussion of what the trim was actually set at?
Simply

That's a good point. Even in their directive last Fall, they didn't include that as a solution. Also, from flight basics, for whatever the trim is set at, it produces more force on the controls the higher the airspeed. Simply keeping the plane at a lower speed would have helped too, which goes along with flaps.

It's down 10% from the peak from a couple months ago.
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