[OT] “Raise the nose, HAL.” “I’m sorry, Dave, I’m afraid I can’t do that.”

[Paolo Invernizzi]

On Sunday, 21 April 2019 at 19:52:58 UTC, Walter Bright wrote:
> On 4/21/2019 10:18 AM, Paolo Invernizzi wrote:
>> I'm finding this article [1] amazing, looking at all the 
>> anecdotical stories that Walter has told us during all that 15 
>> years regarding engineering in avionic industry.
>> 
>> Without specifically discussing the Boing case, but looking at 
>> industry in general...
>> Really, things will go horribly wrong, before starting to go 
>> better again?
>> 
>> Happy Easter to everybody!
>> 
>> [1] 
>> https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer
>
> I have my beefs with the article.
>
> For example,
>
> "They want to have one airplane that all their pilots can fly 
> because that makes both pilots and airplanes fungible, 
> maximizing flexibility and minimizing costs."
>
> Safety is a factor in having different airplanes fly the same. 
> Many accidents have occurred because the pilot, in a moment of 
> stress, applied a solution that would have been correct on the 
> aircraft type he had more experience on.
>
>
> He argues that airplanes are stable without augmentation. This 
> isn't true for any jetliners, they have an active yaw damper:
>
>   https://en.wikipedia.org/wiki/Dutch_roll
>
> In particular:
>
>   https://en.wikipedia.org/wiki/Dutch_roll#Accidents
>
>
> He argues that it would be safer to develop a whole new 
> airframe. Any new airframe, by definition, will be an unproven 
> design, and everything in it would need to be re-proven, which 
> has its limits.
>
>
> "Neither such coders nor their managers are as in touch with 
> the particular culture and mores of the aviation world as much 
> as the people who are down on the factory floor, riveting wings 
> on, designing control yokes, and fitting landing gears. Those 
> people have decades of institutional memory about what has 
> worked in the past and what has not worked. Software people do 
> not."
>
> This is sheer nonsense. People on the shop floor assembling 
> airplanes do indeed have institutional knowledge about what 
> works in manufacturing. They have no idea what works when 
> flying or various failure modes. They have zero experience with 
> stability issues. They do not do design work. Even more 
> ignorant, the 757 I worked on back in 1980 had many computer 
> systems that controlled the airplane, such as the autopilot. 
> Last I checked that was 4 decades ago, and software programmers 
> and managers implemented it.
>
>
> Boeing did indeed make mistakes with the MCAS software design. 
> I won't defend that, I don't understand the causes of those 
> mistakes. But it wasn't about cost saving, another scurrilous 
> charge by the author. The fact that the fix is a software 
> update is evidence enough that it was a mistake, not some blind 
> greed.
>
> Absent from his article is anything about Airbus. Airbus has 
> had crashes due to avionics software problems, too.
>
> The author is a pilot, but has never flown airliners and has no 
> experience with them.
>
> There's more, but I should stop here. I'm just tired of these 
> hit pieces from people who only partially know what they're 
> talking about. I'll fly in a 737Max any day.

It wasn't my intention to touch a nerve, nor my intention was to 
turn it in a derby between Boing or Airbus (frankly speaking, who 
cares?). To be honest, I'll fly any day only on something with 
NASA code running on it  :-P

We will see the reports of the investigation process, but it 
seems really probable that it was the MCAS that crashed the 
planes, and it seems plausible that:
- there's no check from redundancy input coming from the left 
sensor
- there's no check from other inputs too
- there's no a second "unit" running to check for output 
differences.

Walter, you are an engineer, but I'm a manager, so I believe that 
cost saving _could_ be a cause, and a major one.

For example, the quote you have made about "one airplane that all 
their pilots can fly" is related to airlines, not airplane 
builder, and that's a basic rule in organisation to be more 
efficient.

I'm not interested in the specific case. What I'm wondering is if 
software is still not so under the lens of regulation as hardware 
of mechanical engineering in general, so that's a "trend" in 
shifting "weight" from traditional engineering to software 
engineering, and that's starting to be a problem.

- Paolo