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

Uknown sireeshkodali1 at gmail.com
Tue Apr 23 07:31:01 UTC 2019


On Monday, 22 April 2019 at 20:35:31 UTC, Walter Bright wrote:
> On 4/21/2019 10:54 PM, Uknown wrote:
>> [snip]
>
> Actually, I would even in an unmodified 737MAX. The reason is 
> that the way to deal with it, even if pilots don't know about 
> it, is to follow their training for runaway stab trim. This is 
> what the pilots did in the first Lion Air incident, and they 
> landed without incident. In the second LA incident, and in the 
> Ethiopian one, they did not and crashed.
>
> It's simple:
>
> 1. The electric trim switches on the control column override 
> the MCAS commands.
>
> 2. When trimmed, shut off the stab trim with the cutoff 
> switches on the console.
>

Yes, and what you said is inline with what Boeing said after they 
the Ethiopian airline crash :

> In the event an uncommanded nose down stabilizer trim is 
> experienced on the 737 - 8 / - 9, in conjunction with one or 
> more of the above indications or effects, do the Runaway 
> Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are 
> set to CUTOUT and stay in the CUTOUT position for the remainder 
> of the flight.

> Both pilots in the crashes were performing (1). The mystery to 
> me is why they did not continue to do it, then perform (2). 
> We'll have to wait for the NTSB report which hopefully can 
> explain that.

I read an ars technica piece that said that they performed (1), 
however the MCAS they did something else that brought back the 
MCAS system and at this point it was too late to recover. However 
I would rather wait for some official report in this one.

> I would expect with all this publicity even an incompetent 
> pilot would be able to accomplish this.
>
> BTW, I only saw one article publish (1) and (2). (The wording 
> is from memory, I don't recall the exact words in the Boeing 
> instructions.) All the other articles leave it out and prefer 
> to publish hysterical clickbait articles.

https://arstechnica.com/information-technology/2018/11/indonesia-737-crash-caused-by-safety-feature-change-pilots-werent-told-of/?comments=1

This one does mention it, as a press bulletin at the end. Yes 
media is trash and will publish clickbait about everything that 
is remotely technical. They trash every new military project 
without any knowledge of it (LCA Tejas was late, F-35 is a waste 
of money, etc.). No point listening to them. However many pilots 
have complained that they really weren't even aware of the MCAS 
system, with no prior training being given. That's definitely not 
a good sign.

> Boeing still needs to fix the MCAS system, because how 
> airplanes are made robust is to fix every point in the string 
> of failures that led to a crash.

Yes, however the question is how did such a poorly designed sytem 
get approved in the first place?

> BTW, I was a nervous flyer before I worked at Boeing on flight 
> control systems. Knowing how things actually worked and how 
> things were built changed it all for me. An awful lot about 
> what is written in newspapers about technical airplane issues 
> is complete trash. Journalists don't know **** about airplanes, 
> and they garble it all up. If you want the straight dope, read 
> the NTSB incident reports.

How long do they usually take? 4-6 months? I've never been 
interested in an air crash investigation as much as this one.

> The pilot's article linked to sounds authoritative, until one 
> notices he's not an airline pilot, and (for instance) does not 
> realize that all swept wing airplanes are fundamentally 
> unstable, and that Rosie the Riveter knows nothing about 
> stability issues.

I agree this article is nonsense. The idea that code is somehow 
"less safe" or just not good enough for aviation is nonsense. I 
presumed that the rest of the article was true, however you claim 
otherwise. The only true part seems to be

1. The MCAS was poorly designed
2. The plane pitches up (more than an acceptable degree) when 
thrust is provided, which is why the MCAS is necessary

> You don't need to believe anything I say - so I recommend 
> withholding judgement until the NTSB report(s) come out. You'll 
> learn a lot reading them. The NTSB does a good job thoroughly 
> stating the facts and leaving off the hysteria.


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