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Breaking news: Ethiopian Airlines flight has crashed on way to Nairobi
Bobby...do you read anything here or just talk from your rear? (Trust me, it takes one to know one).
THE TRIM MECHANISM OF 737's GENERALLY JAM AT EXTREME SETTINGS AND HIGH SPEEDS.
It's in writing.
Gabieee explained it above (in somewhat nicer terms).
The report indicates that the crew did a seemingly acceptable job trobleshooting their problem (which included stick shakers and speed disagree an INTERMITTENT nose overs), and DID REALIZE THEY SHOULD KILL THE TRIM AND DID KILL IT and did attempt to nose up with manual trim and elevator inputs...
The trim apparently was jammed by aerodynamic forces.
Did I say that the trim tends to jam by aerodynamic forces?
It's one thing to see a stand-alone trim runaway...It's another thing to see intermittent trim input when multiple OTHER warnings are going off...a little delay, and the trim tends to jam up.
Did I mention that the trim can jam by aerodynamic forces, in a long-known response to extreme control and trim settings?...Like when the plane is sneakily, but aggressively nosing over because it's convinced it's stalled...
and the trim basically locks up...
If the crew did something wrong- it appears they weren't reading ass-hat parlour talking aviation forums about strange nose-over behavior of Lion air...
They also reengaged the system. I don't need to talk crap like the Wiki leaks bunch. I lived it for over 47 years. Granted they knew it was coming but my friend did it in the Sim yesterday, and a handful to manually trim but they got it on the ground.
It would have done more than that. It would have killed the MCAS just like the trim cutout buttons but without killing the thumb switch and without needing to rely on a manual wheel that gets stuck.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
And what would have YOU done at that point, and I mean at the point where they re-engaged the system? Hey couldn't hold the elevator back enough any longer and they were unable to turn the trim wheel manually. It was a last resource, they were dead if they didn't re-engage it. And re-engaging it could have saved them if they had actually used the frigging thumb switch to trim nose-up.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
It would have done more than that. It would have killed the MCAS just like the trim cutout buttons but without killing the thumb switch and without needing to rely on a manual wheel that gets stuck.
And THIS is where experience comes into play. Not ALL of us sit back "fat dumb and lazy" like the nub thinks
Actually, if you really know the afflicted system, this is where you want to go:
Yes, but they should have done that immediately after the flaps fully retracted and the MCS activated the 1st time. Shortly later they were already way beyond flaps speed.
At the time that they could have done it, they could have also done other more "procedural" things, like trim with thumb switch BEFORE using the cutout switches (as recommended in the Boeing procedures) and use the trim wheel earlier (before they got so fast and the wheel got so hard), not to mention pulling back on the throttles and pulling more nose-up to keep the speed in check instead of overspending.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
It was a last resource, they were dead if they didn't re-engage it. And re-engaging it could have saved them if they had actually used the frigging thumb switch to trim nose-up.
Thinking outside the box a little here - do we actually _know they didn't use the thumb switches more than a perfunctory couple of times? I get that the data shows the stab only moved a couple of clicks after they re-engaged the electric trim. But that's not quite the same thing. Given their overspeed condition, is it possible that even the motor driving the jackscrew was unable to fight the aerodynamic forces on the stab to move it nose up? In contrast, MCAS found it easy to move it nose-down?
And THIS is where experience comes into play. Not ALL of us sit back "fat dumb and lazy" like the nub thinks
This is what really bothers me. Boeing saw what MCAS could do with the Lion Air crash and responded with this fatal procedure that removes a key system that is perfectly functional instead of simply using the MCAS on/off lever (the flap lever). And so another one bites the dust.
Why didn't they write the emergency AD procedure to be: restore pitch/counter-trim/reduce thrust/extend flaps?
I mean, why is nobody thinking this thing through?
Uh... maybe because the flaps lever is NOT an "MCAS-off switch"?
Yes, if you have complete situational awareness, which is very unlikely in events like those we're discussing here, you could consider using the flap lever to disable MCAS... if you happen to think of it.
But the reality is there are hard-and-fast rules about when flaps should and should not be used, and how much. Adding in "do this if MCAS is going nuts and you want to stop it" to those rules complicates things significantly. And when working a multiple-serious-failure scenario, the last thing pilots need is more complexity.
But the reality is there are hard-and-fast rules about when flaps should and should not be used, and how much. Adding in "do this if MCAS is going nuts and you want to stop it" to those rules complicates things significantly. And when working a multiple-serious-failure scenario, the last thing pilots need is more complexity.
It's a bit late in the day for Boeing to avoid complicting things significantly, but the least complicated solution is still the best one. You can safely extend flaps 1 at 250kts. That procedure I suggest lists 'reduce thrust' before 'extend flaps'. Even if you are 10kts fast at that point, it's better to risk flap damage (unlikely unless you are well above that speed) than to risk losing pitch trim authority.
From everything that has been explained about MCAS thus far, the flap lever is a de facto on/off switch for MCAS.
I semi-agree, but at this point turning off MCAS doesn't seem to be the biggest issue. It can be disabled via the cutoff switches and the Ethiopian pilots did exactly that - the big problem seems to be that even with it turned off, you can find yourself in an unrecoverable situation.
And there's no limit to how much things can be complicated! Sure the "MCAS situation" creates complication for pilots, but that's no excuse for introducing more complication.
It's a bit late in the day for Boeing to avoid complicting things significantly, but the least complicated solution is still the best one. You can safely extend flaps 1 at 250kts. That procedure I suggest lists 'reduce thrust' before 'extend flaps'. Even if you are 10kts fast at that point, it's better to risk flap damage (unlikely unless you are well above that speed) than to risk losing pitch trim authority.
Wouldn't reducing thrust make the nose go down when you are fighting with MCAS? I guess it should work if you immediately concentrate on the trim switches to control the nose, and then you can reduce thrust if it's working well enough
Wouldn't reducing thrust make the nose go down when you are fighting with MCAS? I guess it should work if you immediately concentrate on the trim switches to control the nose, and then you can reduce thrust if it's working well enough
You lose some pitch-thrust coupling. You are already getting nose down from the MCAS, so it's irrelevant: you have to pull up and trim-switch up (steps 1 and 2). Then, extending flaps to flaps 1 (step 4) terminates the MCAS problem, so you can lay off the trim. From there, you just COMMUNICATE and NAVIGATE back to the terra firma under complete control. I don't understand why this wasn't the emergency AD procedure.
Originally posted by elaw
I semi-agree, but at this point turning off MCAS doesn't seem to be the biggest issue. It can be disabled via the cutoff switches and the Ethiopian pilots did exactly that - the big problem seems to be that even with it turned off, you can find yourself in an unrecoverable situation.
Exactly. You're not following me. Turning off the electric trim is a BIG mistake. Turning off the MCAS without turning off the pitch trim is LESS COMPLICATED.
These two crashes will already cost Boeing billions in terms of restitution settlements and lost revenue. We don't wan't to destroy Boeing. We want to repopulate the management. We want to see the top executives responsible for leading Boeing astray go to jail, as we did with the Volkswagen and Audi emissions scandals. We want to a bunch more reduced to flipping burgers. We don't want to do anything detrimental to society or to see good, talented people lose their jobs.
We want to see the 797 rolled out over the coming decade, and for Boeing to reclaim the trust of the people who depend on it.
"restitution settlements" what is that exactly?
lost revenue? they brought that shit on themselves.
i didn't say shutter boeing. but i would narrow the investigation down to every punkass that had anything to do with the max program, grill the hell out of them in public hearings, including the low level folks that only NOW seem to think speaking out is a good idea, when they would have been protected by state and federal whistleblower protection laws and make them at least FEEL partially responsible for the 364 dead. make them look at pictures of every dead passenger and read their names out loud on national TV. i could care less if they flipped burgers or shoveled shit for the rest of their lives. engineers are a dime a dozen...like lawyers. get rid of the shitty ones and keep the good ones.
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