https://graphics.reuters.com/BOEING-737/0100B2J51TY/Boeing%2...
The system affects how the flight stick feels and that's really it. The more you pull up (higher AoA), the more force is needed on the stick. That's supposed to be linear within some margin of error. The big fat new engines took it out of the linear envelope, making it a bit lighter than it 'should' be at high AoA as the engines caught the wind. They either fixed this, or else needed a new type rating (pilots can't hold more than one, so it's a huge issue for existing operators of 737s).
The solution was MCAS which, as originally designed, wasn't powerful enough to cause problems. But test pilots said that the stick was still a bit light, so they reworked it and made it way too strong, while still being invisible to pilots and lacking the reliability of a critical system. Then several hundred people died.
You can hold more than one but you need to maintain each separately.
I kept hearing this too, so I wondered why they didn't just directly change how the stick feels, like with a force feedback system?
And I looked it up[1]: Turns out MCAS was also there to push the nose down at high AoA, to imitate what the 737 NG does even in the absence of control input, so it's not just a stick feel thing.
"The added nose down trim has the side effect of requiring more elevator input at high angles of attack", so simultaneously fixing the stick feel issue.
It seems to me like MCAS solved two related problems at the same time... and sadly thus created an even larger unintended problem.
The transcript (https://tmsnrt.rs/2OZl4Ic) shows them specifically talking about MCAS doing weird stuff in simulators and they they didn't know what was going on, or what the expected behaviour was. Interesting that it happened in a simulator where I presume that sensors don't sporadically break or deliberately give duff readings in what is probably a lot of highly controlled tests... perhaps a pure software error?
Did this problem just get lost somewhere in the noise of development? Was it "unreproducible" (in the bug sense)? Was it willfully ignored by "the management"? Who knows - but we now do know that some people at Boeing involved in development were aware of problems before the crashes.
Pretty sad really.
You could suggest that the trim system is defective regardless of MCAS. That the pilot should always be able to counteract automatic trim in any flight mode.
Or the problem is solely in the max modifications and you can safely ignore issues with the original design.
This sorta worked as long as Boing built consumer aircraft that worked exceedingly well. But alas...
People need to go to prison over this.
>Forkner said in one text message, “I basically lied to the regulators (unknowingly).” The other employee responded that “it wasn’t a lie, no one told us that was the case” of an issue with MCAS.
>Forkner responded soon after: “Granted I suck at flying, but even this was egregious.”
The one about MCAS running rampant is clear enough but what does he mean saying that he sucks at flying? What is egregious?
Interesting that prison time is demanded here when a much more simple explanation is that this was an oversight by the pilots in the sim who didn't fully understand the issue was MCAS related.
Millions killed from opioid epidemics, thousands killed from violence and various preventable diseases, huge number of road fatalities do not result in prison time.
The safety record of aviation in the US should be applauded.
Cold comfort to the 300+ lives, and families destroyed.
Watch this video: https://www.youtube.com/watch?v=H2tuKiiznsY
This isn't just some "oops, these were badly trained pilots" – the whole premise of MCAS is seriously screwed up and smacks of non-engineers running the place.
It kinda turned into a reverse-merger, where MD bosses took over Boeing and heavily influenced the management style and practices thereafter.
Some of the commentary https://newrepublic.com/article/154944/boeing-737-max-invest...
There's deaths caused by Boeing's greed and lack of competition against Airbus' new planes.
There are serious questions to be answered about the corporate governance.
