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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

#231

Post by mlyle »

jakeogh wrote: post #229
mlyle wrote: post #226

Earlier quoted context omitted.

Sure, but 737's have crashed before from crews getting the nose too high on departure, so... arguably the entire 737 fleet would benefit from a "proper" MCAS. The people who built MCAS thought they were taming a 737 handling weakness that was worsened by the new engines. Again-- a normal kind of thing to have to work on when stretching jets.

Not stalling on takeoff is pilot 101. If an aircraft is prone to it I personally do not want layers of software hiding the issue. It's practically a law of nature that software is full of bugs.

Better avoid Airbus, then, because there's a massive control law between the pilots and the actuators to create a "do what I mean" interface with envelope protection and all kinds of characteristics tamed.

https://www.skybrary.aero/index.php/Flight_Control_Laws#Norm...

Boeing has mostly avoided that. MCAS is kind of an unusual form of control augmentation as far as Boeing is concerned.

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

#232

Post by computerex »

kayfox wrote: post #144
ClumsyPilot wrote: post #141

Earlier quoted context omitted.

> 5. 5. The flight computer system and MCAS was implemented problematically, relying on one input because the expected control authority was very low, and then when that was not changed the system was not re-architected. I like your approach: Pilot's failures caused the crash, and Boeing made an honest mistake. And you seem to think it would have been fine flying in the US. You do realise plane crashes and industrial…

So... I said the design was bad and your saying I'm not harsh enough in that? Are we trying to solve engineering problems by getting emotional about them or something?

Out of the six points you mentioned, you blamed everyone, blaming the pilots twice, and merely mentioned this against Boeing:

> The flight computer system and MCAS was implemented problematically, relying on one input because the expected control authority was very low, and then when that was not changed the system was not re-architected.

Do you have a personal stake in Boeing or something? Because you appear very biased indeed. There were several ethical breaches that resulted in these tragic catastrophes.

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

#233

Post by anigbrowl »

inimino wrote: post #162
rossdavidh wrote: post #89

Earlier quoted context omitted.

While I don't disagree, at least moving from test pilots to average pilots would be a big improvement. And, in practice, might mean that you have to simplify and streamline the UI just as much as for the minimum viable pilots. But, even if not, at least average would be way better than test pilots only.

"Simplify and streamline" is exactly not the solution here, in fact the issue was that the relevant information was invisible and hidden from pilots, not that there was too much. Not everything in good design needs to end up looking like a Fischer-Price toy. The main problems from my limited understanding were: pilots didn't know the subsystem existed; they didn't know it had activated; they didn't know what it was d…

True, but too much instrumentation is also a problem.

I'm into synthesizers, which run the gamut from bleep-bloop toys to movie-soundtrack in a box.

Mostly, synths are marketed like 'Not only can the Omnicron Neutron Wrangler produce any sound imaginable, it can produce more of them more loudly than the competition and audiences will surely be impressed by your mastery of its mind-bogglingly vast control surface.'

But the synths which end up being well-loved classics are not the ones with the biggest range or the most controls, they're ones with a decent range which is designed and calibrated well enough that it's hard to get a bad sound out of it - meaning they don't have too many abrupt phase transitions or nonlinear feedback loops that could cause you to suddenly lose control and turn an interesting complex tone into noisy garbage.

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

#234

Post by joe_the_user »

dahart wrote: post #196
mlyle wrote: post #193

Earlier quoted context omitted.

In aviation we tend to look at failure chains . There are many, many things that went wrong: 1. The stuck AOA instrumentation on the plane. 2. MCAS not using redundant AOA information and being fooled by the stuck instrumentation. 3. Lack of clear indication of what MCAS was doing contributing to flight crew confusion. 4. Improper execution of the runaway trim procedure/checklist by flight crew. 5. Training shortcomi…

Agreed! Your comment reminds me a lot of this 1998 article about the ValuJet crash in Flordia https://www.theatlantic.com/magazine/archive/1998/03/the-les... Specifically it's the argument in the article that large disasters often have multiple causes. "Perrow says, Murphy's Law is wrong—what can go wrong usually goes right. But then one day a few of the bad little choices come together, and circumstances take an air…

Specifically it's the argument in the article that large disasters often have multiple causes. "Perrow says, Murphy's Law is wrong—what can go wrong usually goes right. But then one day a few of the bad little choices come together, and circumstances take an airplane down. Who, then, is really to blame?"

But that's exactly what's disingenuous about the GP's claim. Many disasters do indeed involve a sequence of mistakes of different sorts but that's not really the case here. The situation with 737 max was one terribly system and the pilot's complete inability to stop this - inability that could have been anticipated and which was the product of the original bad design.

"His point is that these accidents are science's illegitimate children, bastards born of the confusion that lies within the complex organizations with which we manage our dangerous technologies."

This kind of disaster certainly can happen but the situation with the 737 Max was Boeing pushing an old design far beyond it's limits because of the threat of losing market share and regulators allowing this.

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

#235

Post by Obi_Juan_Kenobi »

dahart wrote: post #62

This seems like a good thing, they should be testing with people who don’t know the answers. Though I can’t help but wonder if this is a very subtle re-framing of the Max accidents to shift blame back towards pilots. This approach of a regulatory agency recommending “average pilot” testing makes both the agency and Boeing look good, and tends to downplay the fact that Boeing intentionally avoided training the pilots,…

> the system was only recoverable if you had some extremely specific knowledge

I don't think this is a fair characterization.

The runaway trim condition is not arcane knowledge. It's a standard part of pilot training and easily something the vast majority of pilots are well prepared to handle.

The issue with MCAS was that, while it was ultimately a runaway trim issue, it didn't look like it from the pilot's seat. The MCAS trim inputs were intermittent and came with no indication that the MCAS system was providing them. You also had throttle inputs and a whole slew of cabin warnings. The fact that the AoA disagree indicator was not standard shows just how little consideration was made to communicate to pilots.

Even with improved pilot training, I think a major crash was inevitable due to the nature of how the malfunction presents itself. More training doesn't make up for the obscure operation of MCAS or the fact that this failure occurs with very little time to react.

I'm in strong agreement that blaming the pilots is unconscionable. The pilots' action disabling the trim with the cutout switch, and then re-enabling it in a desperate bid to regain control of a badly-out-of-trim and overspeed aircraft speaks volumes. They were quickly put into a nearly-impossible situation and behaved reasonably, if ultimately incorrectly.

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

#236

Post by jakeogh »

mlyle wrote: post #231
jakeogh wrote: post #229

Earlier quoted context omitted.

Not stalling on takeoff is pilot 101. If an aircraft is prone to it I personally do not want layers of software hiding the issue. It's practically a law of nature that software is full of bugs.

Better avoid Airbus, then, because there's a massive control law between the pilots and the actuators to create a "do what I mean" interface with envelope protection and all kinds of characteristics tamed. https://www.skybrary.aero/index.php/Flight_Control_Laws#Norm... Boeing has mostly avoided that. MCAS is kind of an unusual form of control augmentation as far as Boeing is concerned.

Thanks. I couldnt agree more. It would make sense if the bar was higher for adding control software than training pilots. To me it seems like the type cert problem was backwards.

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

#239

Post by mlyle »

cmurf wrote: post #230
kayfox wrote: post #132

Earlier quoted context omitted.

The general idea was that pilots would correctly recognize large amounts of undesired and uncommanded trim being runaway trim and perform the checklist to resolve that issue that they are expected to know by memory, since there is a need to execute it fast, without paging through the Quick Reference Handbook. This is not a checklist that was introduced with the 737 MAX, but one that has existed since the introduction…

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 undesirable handling characteristics -- like not being able to manually retrim, or even worse things like aileron reversal-- above it. At some point you need to pull back power.

If you're out of trim because of electric trim misbehaving, turning electric trim back on may not be the smartest thing, too.

And then I can't even understand what happens next: if you touch the trim switch, MCAS can't do stuff for awhile. If they're going to re-enable electric trim, why didn't they then fully fix trim with the trim switch? How is MCAS able to actuate and worsen the existing out of trim condition?

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

#240

Post by IllogicalLogic »

beamatronic wrote: post #159
o-__-o wrote: post #154

Earlier quoted context omitted.

Don’t forget the pilot of the previous LA607 flight was able to recover successfully. Other pilot crew had more flight time, thus more experience. Look at NTSB crash data, experienced crews have a higher chance of lower fatalities in an accident. Why? Because these pilots understand their vehicle like the back of their hand. A 5000+ hour pilot has deep knowledge, for instance, of the hydraulic system of the plane and…

What type of process could be used to make sure that their experience and knowledge gets back into the mainline product?

How about Boeing stops taking cost saving measures that end up throwing unnecessary curve balls at otherwise well trained pilots?

At the end of the day, this is the foundation of the problem.

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