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Comment by WheelsAtLarge | Hacker News Reader

This is a software screwup. It's buggy software due to rush to market. I hope they do an analysis of the whole project. We can all learn from it.

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It's worse than that. When they refitted the 737 with newer, larger engines to create the 737 Max there wasn't enough room, so they were shifted forwards (look at the pictures - the engines are almost in front of the wings). This created a setup where the thrust could make the plane pitch up in certain cituations - the system isn't in balance anymore. Thus the sensor to detect pitch-up and the software to try to compensate for that. A hack to fix a hack. The whole airplane should be redesigned to balance as an 'old' 737. I for one won't set my feet in any 737 Max, whatever software or sensor upgrades they put in. No way.

> This created a setup where the trust could make the plane pitch up

No, not related to thrust. All underwing-engined airliners pitch with thrust. I wish we could stamp out this falsehoid.

The nacelles added aerodynamic effects at high AoA.

Pointing only at thrust is probably inaccurate, I agree. However, several sources point to the shifted center of gravity as a cause of the pitch, not just aerodynamic effects. For example an analyst at Leeham Co. (https://www.latimes.com/business/la-fi-boeing-737-max-crash-...)

Not really, see https://news.ycombinator.com/item?id=19570691 for a good analysis

The software did what it was supposed to, the issue was the specification necessitated by the design change.

Yep, the issues started way earlier than the software. In fact the software is at the very end of the chain here, unless you also want to insert "no training". It all started when they wanted those big engines crammed into an airframe not designed to hold them, so as to try to quickly catch up to shifting market demands being met by Airbus.

How can you say “no training” caused this second crash after reading the article? Did you read the article?

(Edited) They had training (and sundvor didn't say otherwise), but still, remember Boeing's decision that little or no re-training for the Max was needed for pilots already having 737 training.

See e.g. https://edition.cnn.com/2019/03/22/politics/boeing-737-manua...

Thanks, that was what I was referring to. Cheers.

They said no such thing

I'm talking about a chain of causes here. There are clearly multiple factors at play.

I just sounds like nobody really thought about the consequences of MCAS triggering due to faulty AOA sensor input. There should be a dedicated switch to disable MCAS without completely disabling the electric trim motors.

> I just sounds like nobody really thought about the consequences of MCAS triggering due to faulty AOA sensor input.

They did know at least two years before the first crash and decided to not do anything about it.

https://www.reuters.com/article/us-ethiopia-airplane-regulat...

That article is terrible. It's a complete mischaracterisation of what it's sources actually said wrapped up in an attempt to make it relevant to the current MCAS drama.

The software did what it was supposed to

I'm pretty sure that it's a reasonable assumption that an implies requirement of any type of aircraft control software is "don't fly the aircraft into the ground"

This sort of buck passing is what kills people. The software may have performed according to its specification but it didn't do what it was supposed to, or it wouldn't have crashed the plane. Now sure, we could identify where things went awry in the chain of steps from "make the plane fly right" to a detailed functional spec, but when it comes down to it, the software was meant to "make the plane fly right" and it did not.

Software is involved, yes, but the problems are ultimately of management, risks (both underestimated and externalised on airlines, pilots, passengers, and the public), cutting corners, and complexity debt.

Definitely a software QA issue. People are blaming the engines but we couldn't have known, a priori, that software is incapable of compensating for the change in balance. Process should have been in place preventing the delivery of an inadequate solution.

At the cost of 300 lives.

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