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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

#221

Post by anigbrowl »

chrisseaton wrote: post #87
stan_rogers wrote: post #82

Earlier quoted context omitted.

No, it would be about making things safe/usable for the merely competent and not relying on "brilliance".

Right, but my point is there may not actually be any pilots who are merely competent at all skills. The distribution of skills may be more complex than that. You may be making things safe for someone who does not exist, which is pointless, and you'd be better off making things safe for something other than a simple mean average.

You're getting hung up on this, like looking for the individual in a population who exactly matches an average, while ignoring the normal distribution that surrounds it. Don't obsess over the point, just center your window function around it.

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

#222

Post by mlyle »

jakeogh wrote: post #210
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…

0. They added software hack (keeping their cert) to use engines on a aircraft not desinged for them.

I strongly disagree with this one being a real link in the chain.

OK, we put bigger engines on. The 737 is kinda already sporty and easy to get the nose too high on departure. Now it's a little worse with bigger engines.

This is part and parcel for what happens when you stretch planes, adapt new engines, etc; there are minor, associated design changes you need to make to improve handling, etc. Software is a reasonable way to do it.

The criticality of this was badly misunderstood and mis-characterized.

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

#223

Post by anigbrowl »

mark-r wrote: post #149
ebg13 wrote: post #21

Uh oh. What are they going to do when they discover that there aren't any average pilots? https://www.thestar.com/news/insight/2016/01/16/when-us-air-... (HN discussion: https://news.ycombinator.com/item?id=11230287 ) https://www.theatlantic.com/business/archive/2016/02/the-inv... (HN discussion: https://news.ycombinator.com/item?id=11155889 )

A friend of mine was once told to make his product idiot-proof. He said "sure, as soon as you give me the spec for the standard idiot."

That's a really old joke and its purpose is to deflect rather than to illuminate. Your friend was trying to sound smart to distract from his unwillingness or inability to come to grips with the underlying design issues.

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

#224

Post by jakeogh »

mlyle wrote: post #222
jakeogh wrote: post #210

Earlier quoted context omitted.

0. They added software hack (keeping their cert) to use engines on a aircraft not desinged for them.

I strongly disagree with this one being a real link in the chain. OK, we put bigger engines on. The 737 is kinda already sporty and easy to get the nose too high on departure. Now it's a little worse with bigger engines. This is part and parcel for what happens when you stretch planes, adapt new engines, etc; there are minor, associated design changes you need to make to improve handling, etc. Software is a reasonabl…

Regarding the engines, indeed none of them would have crashed without MCAS.

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

#225

Post by mlyle »

cmurf wrote: post #217
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…

What was improper about the execution of runaway trim by either LNI610 or ET302? Those two cases are different. LNI043 and LNI610 are also different but the similarity is 4 of 5 pilots didn't recognize it as runaway trim. And does it? Boeing says it does, but saying things doesn't make it true. It's much more aggressive than the kind of runaway trim pilots are trained for. So again, what was improper? Especially ET30…

ET302 ultimately turned the electric trim back on which was their death knell, in violation of procedures.

A contributing factor to ET302 is that mechanical trim wheel rotation can be very difficult in some flight regimes.

A further contributing factor is ET302 left an unreasonable amount of power in and got to an overspeed situation, which makes rotating the trim wheel yet more difficult. Being trimmed a bit nose down should not kill you. It should be the kind of thing you experience in training.

> It's much more aggressive than the kind of runaway trim pilots are trained for.

Bullshit. A stuck stabilizer trim switch will run away much faster than MCAS, and this is the primary thing they're trained for. The problem with MCAS is that it's an insidious, intermittent runaway-- an unlikely failure mode for a switch.

But sure, add to my list that "the trim wheel is often very hard to rotate manually", and "the flight crew left the thrust levers nearly full-forward creating an overspeed condition".

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

#226

Post by mlyle »

jakeogh wrote: post #224
mlyle wrote: post #222

Earlier quoted context omitted.

I strongly disagree with this one being a real link in the chain. OK, we put bigger engines on. The 737 is kinda already sporty and easy to get the nose too high on departure. Now it's a little worse with bigger engines. This is part and parcel for what happens when you stretch planes, adapt new engines, etc; there are minor, associated design changes you need to make to improve handling, etc. Software is a reasonabl…

Regarding the engines, indeed none of them would have crashed without MCAS.

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.

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

#227

Post by anigbrowl »

celticmusic wrote: post #114
rowanG077 wrote: post #81

Actually they must use the worst pilots. If they use average pilots that means 50% of the pilots might be out of their depth flying that plane. What kind of insanity is this?

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 person is someone who doubles down and either offers different but equally fallacious arguments (if they just hate your proposition and are looking for an excuse to reject it, but wish to conceal that) or refuses to acknowledge their original fallacy (due to embarrassment, stupidity, or perversity).

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

#228

Post by inimino »

OrgNet wrote: post #211
inimino wrote: post #204

Earlier quoted context omitted.

They do try. Avionics is miles ahead of everyday commercial stuff like your desktop computer in reliability and correctness. This is not just about software, a plane is a complex physical system and the idea of absolute control is a fantasy. This is why you need alternatives, failsafes, contingency plans, and training in dealing with unexpected failure modes.

> Avionics is miles ahead of everyday commercial stuff like your desktop computer in reliability and correctness. What OS that they use that is so much better?

Embedded systems aren't using your everyday desktop operating systems, if that's what your asking.

https://en.wikipedia.org/wiki/Avionics_software

> Avionics software is embedded software with legally mandated safety and reliability concerns used in avionics. The main difference between avionic software and conventional embedded software is that the development process is required by law and is optimized for safety.

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

#229

Post by jakeogh »

mlyle wrote: post #226
jakeogh wrote: post #224

Earlier quoted context omitted.

Regarding the engines, indeed none of them would have crashed without MCAS.

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.

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

#230

Post by cmurf »

kayfox wrote: post #132
JanSt wrote: post #106

Earlier quoted context omitted.

My understanding is that the pilots had only about 40 seconds time to solve the problem and were trained for one hour with an iPad (not on the MCAS, but the whole 737 Max). I'm not sure whether this is a question of pilots' standards in the US vs around the world.

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 a runaway trim situation.

6. 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. Colgan Air 3407, same thing, captain pulled back on the yoke during a stall making the stall worse, recovery impossible. Both accidents, each pilot had more than 1500 hours experience.

In US Air 427, the pilots aren't centrally blamed because the failure mode was a) caused by an airplane defect, a servo failure, b) the airplane's subsequent behavior was so abrupt and aggressive that the startle factor was pretty much not that surprising.

So why is it that the standard should be different for ET302 in particular? But also LNI043 and LNI610? Why would the blame not centrally be on Boeing even if the pilots made some mistakes, just like U.S. pilots have also made some mistakes yet weren't blamed as the proximate cause? And what mistakes did ET302 pilots make other than trusting electric trim being reenabled wouldn't immediately try to murder them?

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