121–130 of 347 posts
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Post Lion Air, they should have known that.
Why exactly? if Boeing did not updated the manuals and checklists how would pilots know that? from internet forums? Should a pilots ignore the checklists and try steps he read on the internet ? I could not find if Boeing updated their manuals/checklists after the first crash.
> The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working. This is very damning to Boeing. It's precisely the procedure they prescribed and intended to mitigate possible MCAS caused trim runaway. In light of the fact that they put this in place as a justification for moving the engines forward without reclassif…
It does not appear to be "precisely" the procedure, in that sufficient nose up trim was not selected by the yoke manual trim switch prior to pulling the trim cutouts. And then they did not work the mechanical trim wheel hard enough to reset the residual nose down trim. And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe. And, when they (against procedure)…
One thing that I've wondered though as I've read more about MCAS. MCAS can't kick in till the flaps are fully retracted. Usually when something goes wrong in response to an action, the response is to undo the action. Why isn't the procedure or even the pilot instinct to re-extend the flaps when the nose down occurs just after having retracting the flaps?
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It's true there were aggravating factors, like the inability to manually rectify trim, which (would seem to me) would be a aerodynamic or design issue. The point still stands, the root cause was MCAS, without it this would never have happened. MCAS would not have pitched them into a dive, and even if they were pitched into a dive by some non MCAS system, they would have been able to turn on electric trim and recover.…
> It's true there were aggravating factors, like the inability to manually rectify trim, which (would seem to me) would be a aerodynamic or design issue. I don't see in the report that the pilots attempted to both operate the manual trim wheel at the same time. I'm not sure if its explicit in the training, but in the manual its made clear that pilots may need to work together to move the trim out of extreme positions…
Releasing the stick to assist with the wheel would have meant allowing the plane to nose-dive. This might have allowed them to crank in the stabilizer in time to recover, but they only had 7,000 feet above the ground to work with.
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Doubtful. Older models don't have the oversized, forward-mounted engines, and thus don't have as much of an AoA problem as the MAX does in typical flight conditions. That's the reason the MAX should have been a separate classification with specific hands-on training.
The MAX is stable in normal flight. It's only when you are pitched up does the engine placement make it want to pitch up even more (and it is only a problem at a speed that is low enough that the normal stabilizer control doesn't have enough control authority to push it back) hence MCAS forcing the nose down every so often via the trim. A normal flight does include pitching up but it does not include pitching up at s…
Yes, and it will only activate during that edge case if the AoA inputs are accurate. But they weren't. And so MCAS activated when it shouldn't have, and did things that the pilots could not recover from because they were things MCAS should never have done in the first place. That's the problem.
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Thanks, that makes sense. When the report says that the pilots found manual trim impossible after STAB TRIM CUTOUT, do you think it's referring to an attempt at manual electric trim (expected to fail) or both pilots manually moving the trim wheels with the handle?
My (non-expert) reading is that the co-pilot couldn't move the wheel, while the pilot was engaged in fighting to to keep the stick pulled back (a Swedish pilot tried this scenario in a simulator last week and literally had to keep both arms locked around the stick towards the end). Counter-intuitively, letting go of the stick in brief increments might have been the correct move. Letting the nose pitch down would take…
No, it's worse: the origin airport is at 7000ft elevation. They only had around 1000ft height AGL for all of the flight. So I agree that releasing the elevator at all seems surely suicidal.
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The MAX is stable in normal flight. It's only when you are pitched up does the engine placement make it want to pitch up even more (and it is only a problem at a speed that is low enough that the normal stabilizer control doesn't have enough control authority to push it back) hence MCAS forcing the nose down every so often via the trim. A normal flight does include pitching up but it does not include pitching up at s…
> MCAS is specifically designed for an edge case Source? That's the first I've heard that it's only for edge cases.
It's only supposed to activate in a specific edge case (high angle of attack, manual flight, no flaps, low airspeed). That's been discussed plenty online (including previous threads here at HN).
But that assumes that the angle of attack sensors are accurate. If the AoA sensors are inaccurate, as they were on this flight (more specifically the left one), MCAS can activate when it's not supposed to. That's what happened here.
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> They must cut it at a moment where the stabilizer isn't grossly mistrimmed with respect to level flight, OR they may well need to re-engage it and race the MCAS to get into a close-to-proper trim setup prior to cutting out the stabtrim and assuming manual trim control. All while keeping the plane in the air, reading the manual, and attempting not to lose composure knowing that the same thing has happened to another…
> reading the manual Runaway stabilizer is a memory item, there should be no reading of the manual involved. Unfortunately the design of MCAS defeated the checklist of this particular memory item when in lower flight altitudes - which goes back to the argument that the 737 MAX never should have been given the same type rating as the older models.
> The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working. This is very damning to Boeing. It's precisely the procedure they prescribed and intended to mitigate possible MCAS caused trim runaway. In light of the fact that they put this in place as a justification for moving the engines forward without reclassif…
Just out of curiosity, will there actually be any punishments handed out beyond just a slap on the wrist? Or is Boeing far too large of a corp to take on?
Their priority list is, AFAICT: 1. Find out what happened. 2. Find out why. 3. Find out how to make sure it doesn't happen again. 4. See point 3. 5. See point 3.
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This is an absurd comment. The rule of law works in the USA as much as it does in other developed countries. There is no such thing as "too large to take on". I note though that there is not yet any evidence of a crime having been committed.
> There is no such thing as "too large to take on" Let me get you up to date: "The deal — four years after the 2008 collapse of Lehman Brothers nearly brought down the financial system — was criticized at the time, raising concerns about whether some banks had grown too big to face criminal indictment." "Citing anonymous officials close to the case, the New York Times reports that federal prosecutors spent months deb…
[...Quebec Premier François Legault said that SNC-Lavalin was one of ten publicly-traded companies headquartered in Quebec that the province considers to be "strategic" and therefore in need of protection from a takeover that would force the company to leave the province....]
https://en.wikipedia.org/wiki/SNC-Lavalin#SNC-Lavalin_affair...
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Just out of curiosity, will there actually be any punishments handed out beyond just a slap on the wrist? Or is Boeing far too large of a corp to take on?
Incidentally, Boeing has received billions of dollars in illegal tax subsidies from the US (as in, anti-competitive with non-US manufacturers like Airbus): https://www.bbc.com/news/business-38131611 So it's hard to imagine fines or market penalties actually conveying any productive sense of punishment.
>Back in September the European aerospace giant, which employs 15,000 people in the UK, was on the receiving end when it was found that billions of euros in low interest loans amounted to illegal subsidies.
>Boeing celebrated that moment as a comprehensive victory which would deal a mortal blow to Airbus and result in more US jobs.
>The reality is that neither of these companies can exist without government subsidies.
Both of these companies are strategic assets to the countries that have them. So no surprise here. I'm not even upset at it- it's realpolitik.