Boeing Max groundings

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34 Replies - 1037 Views - Last Post: 30 April 2019 - 06:37 AM

#16 Skydiver   User is offline

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Re: Boeing Max groundings

Posted 18 March 2019 - 01:29 PM

I can't find the CNN analysis anymore, but The Seattle Times has something along a similar vein:
Flawed analysis, failed oversight: How Boeing, FAA certified the suspect 737 MAX flight control system

My reading of that is there is a hardware design issue:

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Like all 737s, the MAX actually has two of the sensors, one on each side of the fuselage near the cockpit. But the MCAS was designed to take a reading from only one of them.


As well as a software design issue:

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The original Boeing document provided to the FAA included a description specifying a limit to how much the system could move the horizontal tail — a limit of 0.6 degrees, out of a physical maximum of just less than 5 degrees of nose-down movement.

That limit was later increased after flight tests showed that a more powerful movement of the tail was required to avert a high-speed stall, when the plane is in danger of losing lift and spiraling down.
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After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.
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The discrepancy over this number is magnified by another element in the System Safety Analysis: The limit of the system’s authority to move the tail applies each time MCAS is triggered. And it can be triggered multiple times, as it was on the Lion Air flight.

One current FAA safety engineer said that every time the pilots on the Lion Air flight reset the switches on their control columns to pull the nose back up, MCAS would have kicked in again and “allowed new increments of 2.5 degrees.”

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#17 ArtificialSoldier   User is offline

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Re: Boeing Max groundings

Posted 18 March 2019 - 01:31 PM

I've heard plenty of criticism about the FAA also. They just can't employ the kind of experts that actually design and build these systems, so when they're doing their certification they leave a lot of testing up to the manufacturer.

Basically, "we have this system that we're trying to certify, but we don't understand how it works or how to test it, so we'll just let you do that."

Actually that sounds a lot like some people that I work with.
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#18 Skydiver   User is offline

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Re: Boeing Max groundings

Posted 18 March 2019 - 02:06 PM

Slightly off topic:
As a skydiver, I can tell you how that is how the FAA ended up certifying a lot of the skydiving equipment -- the manufacturer is closely involved in the certification process -- sometimes even proposing tests that the FAA has not even thought of or considered to be able to test the limits of systems and see what the failure modes are. On the other hand, the skydiving industry has a vested interest in working closely with the FAA -- it builds up trust between the parties. It lets the skydiving community have more latitude for self-policing, and the FAA trusts the self-policing steps taken by the community. When there looks to be a going trend accidents or almost accidents, the USPA calls for a review or slowdown to find out what is the root cause before the FAA even started seeing the trend. When there was series of failed demo jumps, the USPA stepped up its certification requirements to perform demos. When there were multiple wing suit accidents, the USPA took steps to institute some standardization, as well as setup extra safety checklists.
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#19 modi123_1   User is online

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Re: Boeing Max groundings

Posted 18 March 2019 - 02:53 PM

Saw this..

Posted Image
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#20 jon.kiparsky   User is online

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Re: Boeing Max groundings

Posted 18 March 2019 - 10:13 PM

Interesting article from the Times: https://www.nytimes....ted-planes.html

Raises some real questions for the autonomous car fanboys. Some of us have been raising those questions for a while, but now you sort of have to ask: what actually do you expect to happen if the people nominally in charge of the vehicle now only take control when things go sideways? And just why is it that we think things won't go sideways?
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#21 Skydiver   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 04:31 AM

It's funny that you mentioned cars. A co-worker of mine is finding great joy in her new car that can parallel park itself.

On the more serious side, I had to learn how to pump the brakes, and then had to unlearn that when ABS has become standard in almost every car. Should ABS also be disabled to force drivers to relearn good emergency skills?
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#22 andrewsw   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 05:01 AM

Off-topic:
We see people all the time driving while using their mobile; I also saw someone reaching and looking down to find a CD while turning right at a crossroads. I wonder where they are now? Probably looking down (or up) and wondering what happened to them.
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#23 jon.kiparsky   User is online

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Re: Boeing Max groundings

Posted 19 March 2019 - 06:03 AM

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I wonder where they are now? Probably looking down (or up) and wondering what happened to them.


Folks like that, I just hope they die alone and don't take anyone with them.

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Should ABS also be disabled to force drivers to relearn good emergency skills?


I'm trying to think of a circumstance where that would be important, and what I can come up with is: if someone's ABS system went out in such a way that the antilock part failed but the brakes reverted to the traditional mode of operation, and you're on a slick surface. So you tell me, does that sound like a scenario you're concerned about?

To me it feels like a bit of a straw man.
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#24 Skydiver   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 08:32 AM

Yes, it was a deliberate straw man to show that there are some places where driving automation is good. :)
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#25 jon.kiparsky   User is online

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Re: Boeing Max groundings

Posted 19 March 2019 - 10:14 AM

So the point about straw-man arguments is that they don't actually prove anything. That's why they're a fallacy.

Yes, there are cases where technological improvements do actually help with safety, and we should use them. That is not in question. I think anti-lock brakes are a good idea, and if they mean that drivers find it harder to use cars with non-antilock brakes, I'm probably okay with that. I also think that airbags are a good idea, even if they sometimes cause injuries. I also think that steering wheels are good, even though they might conceivably come off in your hands and leave the vehicle uncontrollable. The question is, does this experience with the effect of autonomous planes on piloting skills have any bearing on the current mania for autonomous cars? I think it might, you might disagree. If so, maybe you'd like to offer some more productive discussion of the question?
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#26 ArtificialSoldier   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 10:21 AM

I'll offer this: use of the pejoratives "fanboy" and "mania" when discussing car automation shows you have an inherent bias. Car automation is the future, that's a simple fact. We're going to get there. The beginning might be rocky. I don't see anyone running around with "I heart driverless vehicle" t-shirts or manic mobs pushing for automation now, at any cost, so you might want to re-phrase your argument if you're actually looking for a productive discussion on the topic. Right now I feel like if I jump in on the "manic fanboy" side, even just for the sake of discussion, I'm going to be attacked with passionate arguments against things that I don't even actually believe. Maybe state your own position first, and avoid pejoratives.
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#27 jon.kiparsky   User is online

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Re: Boeing Max groundings

Posted 19 March 2019 - 11:03 AM

Car automation is the present. And as I say, some of it I'm in favor of. For example, antilock brakes and cruise control seem quite reasonable. Automated parking? Well, if you can't park your car yourself, that's sort of pathetic, but whatever, it's probably not going to kill anyone. The question is, how far does it make sense to go? If you've already determined that fully autonomous is the only future, that seems like you've kind of got a bit of bias yourself. After all, the companies trying to make this future seem to be having some real troubles - killing their drivers and various bystanders, founders going squirrelly, that sort of thing. I mean, look at Tesla, they're hardly able to keep their wheels on the road metaphorically speaking. It's not even a sure thing that they'll be in business in two years, let alone delivering fully autonomous vehicles.

But even if you think it is a sure thing, isn't it worth asking whether it makes sense? I mean, if it's really such a sure thing then clearly there's a simple solution for the problem the airlines are running into. After all, they're dealing with a much simpler problem in a lot of ways - they have an aggressively controlled traffic space, they're held to much stricter maintenance standards, they are largely operated by large organizations with huge investments in their equipment and a very intense desire to avoid public-image damage, etc.
The autonomous car that runs you over or slams you into a tree will be operated by you or your neighbor, and none of the above will apply. Furthermore, I see no reason to think you won't be able to modify the vehicle (just as you are allowed to modify your vehicle now) which means we can't even make safe assumptions about the actual vehicles on the road based on what the factory ships. These modifications might be physical - hotrodding your car is an old American tradition, no reason to suppose it'll die out - or they might be software modifications. Imagine the trade in mods for your Tesla - here's a patch to let you run those yellow lights! Here's one to push the speed limit! Here's one to adjust the ethics of the vehicle, so it'll prefer to preserve the safety of those in the car to that of those outside the car!)

So, my position is: the deployment of fully autonomous vehicles is potentially much more hazardous than the promoters of that idea have posited, and it's worth understanding the hazards instead of simply accepting the claims as given.
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#28 xclite   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 12:03 PM

I have 0 confidence that car manufacturers will apply a level of rigor that I'm happy with to the software driving the cars (protip, they already don't). I am a strong believer that automatic safeguards can be a very good thing to deal with what appears to be total callous disregard of the average human driver: automatic braking, steer assist, and other methods of mitigating human failure.

Honestly, I don't really trust either, but maybe together, cars will be safer.
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#29 ArtificialSoldier   User is offline

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Re: Boeing Max groundings

Posted 19 March 2019 - 12:09 PM

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The question is, how far does it make sense to go?

Ultimately? All the way. People suck at driving. It's going to take a long time to get there though.

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If you've already determined that fully autonomous is the only future, that seems like you've kind of got a bit of bias yourself.

Barring a major catastrophic event, I see it as inevitable whether I'm in favor of it or not. It's the natural progression.

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After all, the companies trying to make this future seem to be having some real troubles - killing their drivers and various bystanders

I'm aware of one death as a result of an autonomous car, here in Arizona. If you're referring to Tesla owners dying, those cars are specifically not autonomous regardless of how people try to use them.

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But even if you think it is a sure thing, isn't it worth asking whether it makes sense?

I think that's pretty self-evident. Look at vehicle-related deaths. A better question is whether it makes sense to have private individuals driving cars if safe full autonomy is an option.

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I mean, if it's really such a sure thing then clearly there's a simple solution for the problem the airlines are running into.

Maybe so. "The solution is simple, it's finding the simple solution that is difficult." I doubt it though, I think we have a long way to go and the solution is not simple. The processing that happens in our minds while driving is not simple, and duplicating that is also not simple. But now I'm talking about cars, not planes. In the case of the MCAS system on the MAX 8, that seems a lot more stupid than simple. It should be possible to completely disable that system but for some reason someone decided that's not possible. That's a human decision not relating to the technology at all.

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So, my position is: the deployment of fully autonomous vehicles is potentially much more hazardous than the promoters of that idea have posited, and it's worth understanding the hazards instead of simply accepting the claims as given.

That's a really safe position. I don't have much to say about that, it's pretty self-explanatory. I doubt many people would disagree with that position. I certainly haven't heard any arguments that would counter that position, at least not by anyone in any position to influence anything. Of course there might be unseen hazards. Of course we should try to understand them. I think we can, and we will.
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#30 jon.kiparsky   User is online

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Re: Boeing Max groundings

Posted 24 March 2019 - 06:58 PM

View PostSkydiver, on 19 March 2019 - 06:31 AM, said:

On the more serious side, I had to learn how to pump the brakes, and then had to unlearn that when ABS has become standard in almost every car. Should ABS also be disabled to force drivers to relearn good emergency skills?


Interesting op-ed on this. https://www.nytimes....shift-cars.html
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