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by hn3333 2133 days ago
let me finish your summary:

... but the aerodynamics were changed in the process and they fixed it with software, which was bad.

2 comments

Would have been fine if they hadn't fixed it with crap software that was incompatible with the pilots existing runaway trim checklist.
I bet if we look at the requirements analysis of MCAS, the developers just met the specification. I think the article makes to much assumptions about the state of the industry and developer hubris, but the decision of system design of the plane was probably decided before it reached developers. They might also just have a perspective of this one system, so the result is as expected.
Yup. The UX guys didn't apreciate how critical the software was and how half-baked it was going to be (and therefore require pilots to need to interact with it requiring good UX). The software guys didn't know that the pilots weren't gonna know how to turn off the software so they didn't know they couldn't half bake it. The engine guys didn't know the software guys were gonna half bake it. The AOA guys retired in the 1990s and had no idea the system was gonna be used for anything more than warning lights.

Everyone did their job as it exists on paper but... https://youtu.be/452XjnaHr1A?t=20

It was perfectly compatible with existing runaway trim checklist. The problem was that the pilots didn't recognize it as runaway trim, in part due to pilot error and in part due to the fact they weren't told the capacity for this system to create a runaway trim situation existed.
Fixing aerodynamics with software is nothing new, and isn't always a mistake. The F-16 (a multirole fighter from the 70's) does this.

https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting...

Every modern fighter jet does this, because they're all aerodynamically unstable.
And fighters fall out of the sky quite ofent for no good reason. Luckely the pilots can shoot them self out.
> And fighters fall out of the sky quite ofent for no good reason

What do you mean by that? That they're crashing for unknown reasons? Because that's generally not true. A lot of effort is put into figuring out the causes of crashes. If you're insinuating that the software is generally to blame, I'd like to see your sources for such a claim.

The first F-35 to crash was due to a faulty fuel tube. Was that "for no good reason" or does that count as a "good reason"?

I mean "good reasons" as in storms, collisions with birds or trees etc. No I didn't mean software issues or the F-35 in specific, but fighters in general compared to passenger airplanes.

I didn't find any specific statistics, but I remember reading it in a book about the Swedish airforce some years ago that fighters just crash alot. They seem to just be way more prone to crashing due to their combat agility need.

E.g.: https://economictimes.indiatimes.com/news/defence/13-fighter...

Fighter jets will crash a lot if for no other reason than because they're doing fancy dangerous maneuvering a lot more than any other sort of plane. But I don't think that can be taken as damning the premise of using software to control relaxed-stability aircraft.

Supermaneuverability is the primary reason fighter jets are designed to use such systems, but these systems also see use in other sorts of aircraft for other reasons. The F-117 was stabilized by a computer controlled fly-by-wire system because its aerodynamics were fucked up due to its unusual shape (which was motivated by stealth considerations.) A few F-117s crashed but as far as I know none of those crashes were attributed to software fucking up.

Similarly, the B-2 is inherently unstable (being a flying wing without vertical stabilizer.) Only one B-2 has ever crashed. That one crashed because condensation in air data sensors caused an inaccurate airspeed to be computed. However it's not clear to me that human pilots would have faired any better given the inaccurate data. Even if that crash is blamed on software, the B-2 still has a great track record and the all the public information about the in-development B-21 suggests it too will be a software-stabilized flying wing.

This all said, the 737 MAX isn't even a relaxed-stability airplane.