Boeing 737 Max Simulators Are in High Demand, But Flawed
nytimes.com
nytimes.com
I can’t possibly imagine that the FAA is or any aviation governing body is going to jump from iPad distance learning to full on new type certificate. B737 type rated pilots will receive 2-3 sessions in the MAX simulator and be sent on their way flying 737NG and MAX variants and the aircraft will go on to have a normal safety record.
The more concerning aspect of this entire situation is finding where the system broke down to prevent this additional training to begin with and how do we fix the breaks in that system.
It broke down when pilots who started asking questions about the new controls were shushed and told they'd probably never notice it in the real world.
https://www.cbsnews.com/news/boeing-737-max-audio-reveals-pi...
> So we try not to overload the crews with information that's unnecessary so they actually know the information we believe is important,
But there is that bit of censorship, basically being told pilots don't need this information, and that's why it wasn't given.
What they "didn't need to know" killed a lot of people.
No, you said pilots asked questions and were shushed.
You're being dishonest.
Alternatively, you could put an actual torque sensor between the motor and the control wheel, which might buy you some accuracy at considerably more expense. For a flight simulator, expense is unlikely to be an issue -- I tend not to have that luxury, and typically don't need that much accuracy anyway.
These kind of control systems are all over modern aircraft, much less simulators. Any new grad control systems engineer should be able to knock something like this out.
Or you just buy a COTS servo that does all that for you. Just saying, hardly a need to reinvent these particular wheels...
"What the U.S. crew found was eye-opening. Keeping the aircraft level required significant aft-column pressure by the captain, and aerodynamic forces prevented the first officer from moving the trim wheel a full turn. They resorted to a little-known procedure to regain control."
If you're training for trim runaway it would be helpful to simulate the full forces but I'm not sure if it reflects a worrying lack of preparedness.
The most important fix is that the MCAS should not be able to put the trim in an extreme position, the fact that it did is quite worrying.
This particular article seems much ado about very little.
There seems to be massive issues with the force required.
Root problem seems to be: Software puts trim in an extreme position. It should never do that.
Aviation Week article: if you are in an electric trim runaway, you need to turn off electric trim, then in order to turn the trim wheel manually, you need to nose down to reduce aerodynamic forces. Seems necessary to train for which it suggests was not the case.
NYT article: Simulator doesn't simulate the forces on the trim wheel correctly (although Aviation Week suggests they were able to simulate something useful)
The NYT article really seems like the least of the problems.
This isn't directly the same thing as saying the MAX will stall itself: if you aren't pulling back on the yoke near critical AoA then you don't stall. It's just easier to stall with the yoke than regulations say it must be. MCAS "fixes" that handling issue.
I don't think an audible warning would be sufficient to turn unairworthy behavior into airworthy, so if all the assumptions above are correct, that's why it has to use trim -- or a stick pusher, but perhaps that wouldn't have enough control authority and also I'm not sure the MAX has a stick pusher, as opposed to just a stick shaker. It's a very mechanical cockpit, in general the forces you feel are coupled to aerodynamics, in stark contrast to an Airbus (or even more modern Boeing airframes).
In the working case, MCAS presumably triggers at a particular AoA, trims nose down (but is this a fixed amount and what is it?) which in effect requires more stick back pressure to maintain the angle of attack. Thing is, it seems like MCAS, again in the working case, has a trigger AoA and will incrementally nose down until it goes below some defined angle of attack - which is not really a stick force moderator alone. It's acting as a kind of AoA guardian.
High Angle of Attack. The power can create a pitch up in some circumstances, but the AoA is the primary driver of the extra lift.
As this story develops, it sure seems like there are either gaps in Boeings QA program or there is a culture that overrides quality concerns
Actually, "must" not "should". Aeronautics certification standards require tools such as simulators to be qualified for their intended use. Similar requirement have been introduced in recent release of railway standards.
I guess my question is: why didn't the QA flag get raised on this or if it did, why wasn't it given any credence?
I'm not trying to armchair quarterback this, but I'm legitimately curious if this issue is one the certification process is expected to catch
[1]: https://www.faa.gov/about/initiatives/nsp/media/14CFR60_Sear...
There are whistkeblowers currently willing to testify as much, based on information released to Australia's 60 Minutes 737 Expose.
More importantly, you don't grab the trim wheel while it's moving... If the aircraft is operating normally, you use the trim switch on the yoke.
The only time you'd spin the trim wheel by hand is if you've had to cutout the electric trim motor... and once that's done it's not going to move on its own anyway.
Unless the short is somewhere where you don't expect it to be, which is why a memory item if the runaway trim continues is
STABILIZER TRIM WHEEL - GRASP and HOLDYes, thanks. I guess I pass for now.
> "The system is explicitly designed to override pilot action and prevent them from regaining control authority, in order to avoid an inadvertent stall."
If it's not an anti-stall system what would you characterize it as?
If I'm not mistaken, MCAS was put in to fulfil certification requirements stipulated in 14 CFR § 25.173 - Static longitudinal stability, and § 25.175 Demonstration of static longitudinal stability, which states that "The stick force curve must have a stable slope". The MAX has a curved slope in some regions of the flight envelope, due to the fact that the nacelles generate lift in front of the centre of gravity. (It is not clear to me whether the slope of the stick force at high AoA in a MAX without MCAS goes negative, or just decreases (while staying positive)).
Note the Wikipedia article you quote also says:
> It is thus distinct from an anti-stall device, such as stick pusher which physically moves the pilot's control column forward when the airplane is approaching a stall.[5]
See also here [1]:
> Numerous reports have incorrectly said that MCAS is a stall prevention, or stall recovery, system. It is a Maneuvering Characteristics Augmentation System and would not be expected to activate during any normal flight conditions.
Or here:
>> It does seem MCAS is closely related to protecting the plane from entering a stall scenario.
> Only in the sense that it is giving the pilots the feedback, through the stick force, about how close the plane is to a stall, that the pilots are used to from previous 737 models. The point of MCAS is that without it, the stick force feedback as a function of angle of attack would be different from what the pilots were used to, so they might misjudge how close to a stall they were.
[1] https://www.pilotsofamerica.com/community/threads/engineers-...
[2] https://www.physicsforums.com/threads/boeing-737-max-mcas-sy...
> In a tense meeting with the American Airlines pilots union after the crash, a Boeing vice president, Mike Sinnett, said he was confident that pilots were equipped to deal with problems, according to an audio recording review by The New York Times. A top Boeing test pilot, Craig Bomben, agreed, saying, “I don’t know that understanding the system would have changed the outcome of this.”
Should that be Craig Bomben "disagreed"?
Boeing's procedure only works if you catch it quickly. If you let MCAS trim the aircraft too much it is difficult to recover, particularly at low altitude.
1. Both stab trim cut switches now cut electronic horizontal stabilizer trim control and automated control together.
2. And manual control does not function at high airspeeds.
3. So... A planeload of people is screwed...
That seems like a really risky set of design choices.
Remember, Boeing at the time had not disclosed MCAS to the pilot community. Both speakers are from Boeing, and the first one says that the accident pilots, even though they did not manage to fix the problem, were well equipped (by standard Boeing procedures for stab trim runaway) to do so. The second speaker agrees, saying that knowing about MCAS would not have made any difference.
The article directly quotes him as saying, "I don’t know that understanding the system would have changed the outcome of this." The "this" refers to a deadly crash in which everyone died. He is saying that if a pilot knew about MCAS, the plane still would have crashed. He said this in response to a claim that pilots didn't need to know about MCAS. That is disagreeing by using sarcasm. The Times interprets it though as agreeing and doesn't see the sarcasm.
To summarize:
Claim: Pilots don't need to know about MCAS.
Response: Correct, even if they knew, given the system's flawed design, everyone still would have died in this case, so, technically, knowing about it wouldn't have helped.
Now maybe that's not what he meant. But it looks like he did. I don't believe that the context of the conversation supports an interpretation that he was agreeing that sufficiently skilled pilots would not have crashed whether or not they knew about MCAS given that he refers to "the outcome of this" not changing, the "outcome of this" being the crash.
The classic Stabilizer Trim Runaway is a continuous uncommanded actuation of the trim mechanism on a particular direction.
Catastrophic MCAS failure manifests as a series of discrete, amplifying activations, which are far easier for a pilot to dismiss as the normal operation of the Auto-Trim, and speed trim systems.
The is is a manifestly different pattern to look for, and was only caught by one air crew (on the penultimate flight of the Lion Air aircraft) by the assistance of a third, uninvolved pilot along for the ride.
I understand how one could see Boeing's internal test pilot as being reasonable, but keep in mind who signs his paycheck, and future prospects for him if the company gets found liable.
Perspective, and understanding of what different parties have at stake is essential in evaluating what is actually being communicated, and why. Words have long tails in the aftermath of a crisis like this.
Boeing is only arguing this because if they say simulator training is necessary, then the plane must be recertified. Their executive MBA analyst and stock watcher types under no circumstances will tolerate recertification, therefore regardless of facts, their position must be that simulator training is not necessary. Even though it obviously is. Key point to observing this and everything else about this debacle is that Boeing has no concern whatsoever for safety, professionalism or lives, and is only interested in their own profit, executive bonuses, and stock dividend gains and will do absolutely anything to protect those, even though it inevitably is going to lead to another crash and more deaths. At which point they will again start by doing everything they can to blame the pilot and the culture of whatever country he hails from, as well as paying shills to post nonsense and attack pilots, engineers and others who question their narrative publicly.
The other half is that the FAA -- which is meant to be the counterweight to those perverse incentives -- is no longer credible.
(I've made this point before [0] but it bears repeating here.)
No snark intended.
I’m likely missing something.
"(idiomatic) To argue or promote an idea."
It isn't enough to just say a statement when you want to make a point. It's usually expected, especially here on HN, to put some effort into demonstrating why you believe that statement is true, something which his linked comment doesn't do. It doesn't need to be anything elaborate, even references to other comments mentioning things FAA has done would be more than enough to make the point, which gives people something factual or "real" to respond to or look into.
I don't think there's anything wrong with his statement per se. You don't always need to write a treatise whenever you want to join a discussion or throw in your two cents. Just that when he says he's made the point before, it'd be more helpful to link to something more substantial than the same statement in a different place.
Enron and the 2008 crisis also put in question the need for banking regulation.
"Anything you say can and will be used against you" means you will never get to the truth of what caused an accident, and it will be much less likely to ever get fixed.
Furthermore, if you criminalize mistakes, you'll have a hard time getting top quality people to work in the industry.
Generally, I agree with you.
If that's indeed the case, it is likely motivated by fear. Any admission of error leaves Boeing open to massive lawsuits and the regular calls for criminal prosecution. This entire issue has played out in the media with daily newspaper articles for months. It's quite unlike any other airliner accident investigation I recall.
Don't forget that it's also what their customers wanted.
As an Engineering firm, your job is to tell the customer, "I'm sorry, I cannot give you approval to do that." The idea being that you, the Engineering Authority, are bound by professional ethics, and a commitment to the public interest.and equipped with the specialized knowledge required to determine the outcomes of a design before it is actually rolled out.
It is never justifiable to make an unsafe bridge. Airplanes are no different. No matter the size of the money bag.
Typical article which does not address the entire context of the issue. In other words it isolates what a 737 simulator can't do without regard to what a typical simulator (for another aircraft or by even a different manufacturer) is or is not able to do. [1] The idea is to make the manufacture look like a total ignorant screw up in every way to create anger and compelling content.
[1] This is like a news story talking about what a company fails to do and then gets hacked without talking at all about how likely the same thing happens at another company.