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

Uknown sireeshkodali1 at gmail.com
Mon Apr 22 05:54:26 UTC 2019


On Sunday, 21 April 2019 at 19:52:58 UTC, Walter Bright wrote:
> On 4/21/2019 10:18 AM, Paolo Invernizzi wrote:
>>[snip]
> 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.

I think the point there was that the practical "evolutions" that 
could be done to the 737's airframe was done, so Boeing pretty 
much had to make a new airframe if they wanted to compete in the 
same market. I'm not an expert so I can't comment on the validity 
of this claim. However, I can say that the idea that a plane can 
leave safe controlled flight and pitch up at extreme rates, when 
the thrust is at max, is not something that should be an 
acceptable trade-off.


> "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.

Ypu need to see more than just the failure of the design of the 
MCAS. From many media reports, its been said that the pilots were 
taught that this is the same plane. That was a selling point. No 
need for re certifying pilots. However the plane behaves 
differently enough from previous planes that this is demonstrably 
false. Also the MCAS seems to be a "prevent the plane from 
crashing, *after* stall like conditions have been detected", as 
opposed to "make the plane fly like the previous 737 generation".

To recap:
- Boeing fails to tell pilots what can happen under certain 
situations (specifically thrust increase results in higher than 
acceptable pitch up)
- Boeing fails to train pilots about what to do with regards to 
MCAS when the system makes incorrect inputs
- Boeing makes MCAS with poor design decisions that never should 
have made it onto a production commercial airliner.

> Absent from his article is anything about Airbus. Airbus has 
> had crashes due to avionics software problems, too.

Its not just avionics problems. Many planes have suffered from 
avionics. Its the surrounding corporate negligence, and the 
incredibly bad design of the MCAS that make this incident 
important.

> 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.

I'm sure you wouln't fly in one until the fix has been published 
and the pilots have been trained.


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