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Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

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Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#301

Post by cmurf »

mlyle wrote: post #239
cmurf wrote: post #230

Earlier quoted context omitted.

3. Who had a simulator that simulated MCAS upset? 4. Which is not at all what happens with runaway trim. Also runaway trim that pilots are trained on is a consistent and relatively slow trim. The MCAS upset form is intermittant, and can be but isn't always, aggressive and comes with a ton of other data in the form of various instrumentation disagree warnings and possibly stick shaker going off which NEVER happens in…

> And what mistakes did ET302 pilots make other than trusting electric trim being reenabled wouldn't immediately try to murder them? Like I told you before: overspeeding the plane, preventing them from restoring the trim condition with the trim wheel. I get that if you're not climbing as much as you'd like, it's tempting to have a ton of power in. But the maximum airspeed of the plane is chosen because there are unde…

Runaway trim checklist doesn't call for a power reduction. A power reduction for transport category airplanes always causes a nose drop, a requirement of certification . Attitude for ET 302 was already too low, further altitude loss isn't acceptable. Manual trim was jammed.

20+ degree down angle inside of three seconds. The negative G sent them to the roof. I'm a certified fight instructor, and I've never experienced negative G.

MCAS killed them.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#302

Post by mlyle »

cmurf wrote: post #300
mlyle wrote: post #277

Earlier quoted context omitted.

> Boeing's design and US-centric expectation of pilots didn't prevent US Air 427 from crashing. Literally everyone in the world expects pilots won't pull back on the yoke at stall. Yet these U.S. pilots did that. The reason that '427 pilots aren't blamed is that it's unclear that with perfect inputs that the plane was recoverable. We also excuse them a bit because the situation became unrecoverable in a matter of sec…

It's long since been demonstrated the airplane was recoverable. With perfect information. Lacking stall, full opposite aileron successfully counteracts rudder.

This is untrue. There is a crossover airspeed above the stall speed where rudder wins.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#303

Post by mlyle »

cmurf wrote: post #301
mlyle wrote: post #239

Earlier quoted context omitted.

> And what mistakes did ET302 pilots make other than trusting electric trim being reenabled wouldn't immediately try to murder them? Like I told you before: overspeeding the plane, preventing them from restoring the trim condition with the trim wheel. I get that if you're not climbing as much as you'd like, it's tempting to have a ton of power in. But the maximum airspeed of the plane is chosen because there are unde…

Runaway trim checklist doesn't call for a power reduction. A power reduction for transport category airplanes always causes a nose drop, a requirement of certification . Attitude for ET 302 was already too low, further altitude loss isn't acceptable. Manual trim was jammed. 20+ degree down angle inside of three seconds. The negative G sent them to the roof. I'm a certified fight instructor, and I've never experienced…

> Runaway trim checklist doesn't call for a power reduction.

No, but overspeed does.

> A power reduction for transport category airplanes always causes a nose drop a requirement of certification

Please cite. If you point to 25.173/25.175, note that it refers to trim speeds and return to trim speed, not power. The plane was climbing before crossing Vmo / power could be reduced to maintain Vmo and the current climb rate.

> I'm a certified fight instructor, and I've never experienced negative G.

What? You've earned a spin endorsement, then. You've experienced the little negative G (in most planes) as you tip and enter the incipient spin. It's fun. The first time I did it I said "oh shit" and let go of the yoke to grab my seat. :P Also kinda alarms me that if you're an instructor you've never pushed a little negative.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#305

Post by jeffrallen »

anigbrowl wrote: post #227
celticmusic wrote: post #114

Earlier quoted context omitted.

I don't believe the wording means arithmetic average. It's more akin to the reasonable person test in law. Meaning, a reasonably well trained pilot that is not considered significantly more expert than those around him or her.

Just a side note from a law nerd. 'Reasonable person' doesn't mean 'typical' or 'ordinary' person, it means 'person who is amenable to reasoned argument.' Suppose you make a proposition to a person and they reject it based on some fallacious argument. You, an intellectual, kindly point out the fallacy in their objection. A reasonable person is one who takes this in and reconsiders your proposition. An unreasonable pe…

So, like, an NPR listener vs a Fox News viewer?

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#306

Post by IllogicalLogic »

Dylan16807 wrote: post #278
IllogicalLogic wrote: post #241

Earlier quoted context omitted.

It's an appeal to "intelligence of operator" to coverup for poor design.

That's a tradeoff that will always exist, and cannot be eliminated. The question is where you set the tradeoff for various systems.

The tradeoff where the designer introduces an edge case where a plane crashes unless a pilot has specific additional information?

From my understanding of the issue, Boeing just needs to stop the cost saving measures that led to needing software to stabilize an otherwise unstable plane.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#307

Post by perl4ever »

mlyle wrote: post #274
x0x0 wrote: post #269

Earlier quoted context omitted.

You seem quite knowledgeable. You disagree with the statement that roughly the urge to avoid recertifying pilots caused Boeing to not mention MCAS even in manuals, leading directly to these deaths? Because from my pov, Boeing introduced a new failure mode (MCAS failure leading to intermittent forcing of the nose down) without any warning to the pilots. Now maybe the pilots' standard training should have compensated,…

I disagree that deciding to stretch the 737 is fundamentally bad engineering. Yes, it realistically requires some control augmentation (and maybe earlier 737's should really have had something like MCAS, too). Yes, bigger engines and heavier 737's have the problem worse, but it isn't unreasonable to fix this with systems. I think there were failures across the board. The fundamental analysis of MCAS was flawed: it wa…

I don't have any technically knowledgeable comments to make, but I think if you don't fully understand what happened, there's no excuse for doggedly insisting one group of people involved should be given the benefit of the doubt and the other not. It's reasonable to assume we lack something when it comes to the crew's POV.

Actually, I have one thing to contribute, that I often think of whenever I read about an air disaster. Experts frequently say "why didn't the operators do logical thing X?", and I think there is a practically universal answer. Whenever something unusual goes wrong, it is likely to upset your existing logical model. You know either your logic is faulty or the inputs to your model are wrong, but which is it and how?

It's easy to say "just do A, B, and C as trained", but once jolted out of your mental context, you probably can't regain it in a few seconds or minutes before crashing. The impossible task is not to know the necessary actions according to the book, but regaining the trust that they are the right ones in the face of something unexpectedly violating your assumptions.

Developing a new logical model for reality is very difficult even for highly trained people, particularly under time constraints and life-or-death pressure. Or, even the meta-problem of knowing whether it is time to develop a new model of reality.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#308

Post by perl4ever »

makomk wrote: post #265
treis wrote: post #168

Earlier quoted context omitted.

With the benefit of hindsight it looks obviously wrong, but without that the reasoning looks sound to me. IMHO, the failure lies in validating the analysis with realistic test conditions. They should be testing their assumptions against the worst pilots, not the best.

The problem with their testing wasn't just that they tested against the best pilots. They simulated MCAS failure as just the stabilizer trim running away, which of course their test pilots caught. Real-world MCAS failures were accompanied by a bunch of warnings about loss of accurate airspeed and altitude (because those also used the angle-of-attack sensor), which meant that in reality pilots were occupied trying to…

Doing X number of complicated routine things at once, in general, is infinitely easier than any situation where you are suddenly told "part of your system isn't reliable, now come up with a new model of what you can trust on the fly".

It boggles me how people can't put themselves in the place of someone in the latter situation. Like, even if you haven't crashed a plane, haven't you experienced something similar on a small scale? Haven't you observed other people with such problems?

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#309

Post by mlyle »

perl4ever wrote: post #307
mlyle wrote: post #274

Earlier quoted context omitted.

I disagree that deciding to stretch the 737 is fundamentally bad engineering. Yes, it realistically requires some control augmentation (and maybe earlier 737's should really have had something like MCAS, too). Yes, bigger engines and heavier 737's have the problem worse, but it isn't unreasonable to fix this with systems. I think there were failures across the board. The fundamental analysis of MCAS was flawed: it wa…

I don't have any technically knowledgeable comments to make, but I think if you don't fully understand what happened, there's no excuse for doggedly insisting one group of people involved should be given the benefit of the doubt and the other not. It's reasonable to assume we lack something when it comes to the crew's POV. Actually, I have one thing to contribute, that I often think of whenever I read about an air di…

I really don't understand many of the responses to what I'm saying.

I have already stated that MCAS was a horrible screwup and failure in analysis and regulation. Any system that routinely puts people to the test requiring high performance to avoid death is bad.

That doesn't mean one should ignore the other weaknesses. Given that both the countries with crashes didn't require pilots to demonstrate coping with stab trim runaway as part of type training... and pilot understanding of the stab trim system under stress seems lacking... maybe that should be addressed too.

Re: Plane Tests Must Use Average Pilots, NTSB Says After 737 Max Crashes

#310

Post by Avalaxy »

chrisseaton wrote: post #51
Avalaxy wrote: post #30

Earlier quoted context omitted.

Most commonly it is used for the mean though...

Mean wouldn’t make any sense in this context. Does a mean pilot even exist? Median pilots exist by definition.

If you can order pilots by some quantifiable measure, you can also take the mean of that and select pilots that are exactly the mean or closests to the mean.
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