241–250 of 347 posts
1. Using the input from a single AoA sensor as the single source of truth. 2. Not ticking the box on the AoA DISAGREE alert option on the order sheet. 3. Not using electronic override to neutral before STAB TRIM CUTOUT.
Earlier quoted context omitted.
That's what I think is most interesting. Given the position they found themselves in, going against the directive from Boeing to leave the trim cutout for the duration of the flight, means they were desperate to get the trim back up. So why did they not immediately make use of the reenabled electric trim control to counteract MCAS for as long as it took? They had kept the plane flying up until reenabling the electric…
They made two small trim up commands. But looking at the flight data graph, the stablizer on the bearly moves. The motor was probably stugling against the aerodynamic forces too. Prehaps they didn't think it moved at all and decided they stablizer was jammed. 5 seconds later, MCAS commands down and because that's in the same direction as the aerodynamic forces it moved a lot easier.
Yeah, from my computer screen I can wonder why they didn’t sit on that ANU switch hard and long. But in that cockpit Boeing had already sealed their fate.
> 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?
It is certainly within the realm of possibility that there will be severe consequences, up to and including criminal charges.
Earlier quoted context omitted.
> But high enough to re-enable a system you know is malfunctioning? They couldn't land with the stabilizers mis-trimmed. If the wheel wouldn't budge, re-enabling it and trimming electronically was the only option likely to occur to them, since the only other possible option (release the column, let the plane nose down so that the forces on the screw ease and they can trim manually) is completely counter-intuitive and…
>They couldn't land with the stabilizers mis-trimmed. If the wheel wouldn't budge, re-enabling it and trimming electronically was the only option likely to occur to them, since the only other possible option (release the column, let the plane nose down so that the forces on the screw ease and they can trim manually) is completely counter-intuitive and was removed from Boeing's documentation and simulator training 30-…
The stabilizer's trimmed down. The pilot is repeatedly requesting the co-pilot's assistance in maintaining elevator trim up, and says to the co-pilot at 05:43:04 that the pitch is not enough to keep the plane level. They're well above Vmo at this point.
Per the Seattle Times coverage, a Swedish pilot simulation of the conditions could barely control the column to stay level: https://www.seattletimes.com/business/boeing-aerospace/boein...
> In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated: They moved the stabilizer to push the nose down. They set the indicators to show disagreement over the air speed and followed normal procedures to address that, which increases airspeed.
> They then followed the instructions Boeing recommended and, as airspeed increases, the forces on the control column and on the stabilizer wheel become increasingly strong.
> After just a few minutes, with the plane still nose down, the Swedish 737 training pilot is exerting all his might to hold the control column, locking his upper arms around it. Meanwhile, on his right, the first officer tries vainly to turn the stabilizer wheel, barely able to budge it by the end.
They're absolutely not climbing 14,000 feet in that condition. The control forces on the column in this situation are absurd. Their arms couldn't have held them level for more than a few minutes max.
Retracting the stabilizer was their only option.
> 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?
- Boeing will lose 10s of billions of dollars because of this in damages, lost contracts, and redesign costs.
- Their CEO will resign.
- The FAA will revamp many procedures to vastly increase certification costs and not allow these types of same-class-rating bullshit.
- The FAA or similar EU agencies may slap some fine against Boeing
- The families will sue and win a large settlement.
- One or more engineers may commit suicide. (which would be itself tragic)
- Middle management will pay zero or nearly zero price.
- No one will be internally fired by Boeing as the problem is systemic.
- No criminal charges.
Many of these things will only happen with a sustains public relations compaign against Boeing, congressional hearings, persistent news articles, documentaries highlighting the harrowing crash, etc.
EDIT: I’d say there’s a small chance even that a system called MCAS never flies again, even if that means the entire MAX concept has to be shelved.
If the MAX can fly without MCAS but just under a new type rating, that could be the way they go. Boeing simply has not been successful introducing computer-moderated flight controls and envelopes the way that Airbus has over the last decade (and those lessons were hard learned too).
The design of this system, from what I've heard so far sounds insane . For some background, systems intended to automatically override pilot input upon detecting an impending stall have been used on large, complex aircraft for a long time. The most common mechanism is a stick pusher, which mechanically pushes forward on the stick to mimic what a pilot should do about an impending stall. The force of a typical stick p…
> "A stick pusher, or a pilot pushing forward on the stick is not enough for the aerodynamics of the 737 MAX in certain circumstances. The position of the engines means the thrust tends to push the nose up, and at low speed, the elevator controlled by the stick alone is not enough to push the nose down when nearing a stall. Instead, the trim must be used, which moves the whole horizontal stabilizer rather than just t…
What's different is that at low speed, high thrust, and high angle of attack, the elevator of the MAX does not always have enough pitch moment to reduce the angle of attack.
I'm inclined to say having an elevator that's not effective enough to recover from all the stall conditions regulators test for without help from the trim is probably a flaw. Whether there's a good technical reason the elevator couldn't be more effective (probably just bigger), a regulatory reason (some rule says it's not a 737 anymore if they change it), or a non-technical reason (e.g. more shared parts to make it cheaper), I can't guess.
Reading through the chronology in section 1.1, it feels like a movie where the aircraft is a malevolent entity that's trying to kill them. So if I were in the cockpit I'm sure it would've been some mix of fear and anger. My life's not in danger though, so I'm only left with the anger, on their behalf, knowing some greedy bunch of assholes were effectively that malevolent entity, whose will was expressed via the aircr…
Someone actually downvoted and argued against me that their dog's life is more valuable than "a stranger's". I have no doubt it's the same people downvoting your comment. I can't tell if these people are just really good trolls, or they truly don't value human life (including loss of life in an airplane crash).
Earlier quoted context omitted.
On HN you can say the same things you say anywhere else but GP didn't couch his rant in fancy synonyms and misused Latin phrases like a priori.
I really like this comment because I agree and was trying to write a comment that said this but not in a toxic way. People act like Hacker News is some bastion of discourse that is raised above the rest of the internet but it's not. Most of the comments I read are people stroking their ego's and enjoying the echo chamber.
Earlier quoted context omitted.
> knowing some greedy bunch of assholes were effectively that malevolent entity, whose will was expressed via the aircraft. If this it true then link? When was this confirmed? Who are the assholes? Else this is just Reddit spam that contributes less than nothing.
The "greedy bunch of assholes" are the Boeing execs who optimized for profit over the lives of those pilots and their passengers. (I thought that was pretty clear from the comment, fwiw.) I think it's been pretty thoroughly established at this point that an underlying design constraint in the MCAS was that it was easier for Boeing to get a 737-with-modifications approved than a new airplane, despite the engines being…