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by mattlondon 2431 days ago
The implication is that people at Boeing knew there were problems with MCAS before the crashes happened. I am not saying these particular guys are at fault.

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.
2 comments
MFLoon 2431 days ago
Simulators can "break" in the sense that support simulating various failure modes, including presumably sensor malfunctions. It's very possible that they stumbled on the exact conditions that led to the real world crashes, which would be even more damning.
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mattlondon 2431 days ago
Yeah absolutely but if you are running a simulation/test would you deliberately inject some random sensor failure if you are doing your tests for something else?

It is not clear what they were testing - perhaps they were indeed testing the MCAS system with sensor failures, but if so I probably wouldn't have expected such a surprised resction from them. It seemed like it was totally unexpected and unexplained, which is not a reaction I would expect if they were testing this.

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jjoonathan 2431 days ago
AoA sensors are far from specific to MCAS. They may have been injecting AoA faults to test some other system that depends on the AoA sensors.
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mattlondon 2431 days ago
Sure - but either way it doesn't look good.
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7952 2431 days ago
I guess the response would depend on if you think the flaw is in the existing type or not.

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.

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