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Comment by Angostura | Hacker News Reader

The other key take away I had was:

> "Boeing knew the approach might be questioned [Calling MCAS a simple addition to Speed Trim], so it sought input from its FAA-designated authorized representative (AR) "to ensure this strategy is acceptable” for certification.

> "After speaking with the [AR], concurrence was provided that we can continue to use the MCAS nomenclature internally...while still considering MCAS to be an addition to the Speed Trim function,” the memo said. "This will allow us to maintain the MCAS nomenclature while not driving additional work due to training impacts and maintenance manual expansions

I can imagine some Boeing employees being uncomfortable, but having it run past the FAA would have relieved that. Pretty shocking regulatory lapse. I know nothing about the AR system - is this a Boeing employee, or someone who works full-time for the FAA?

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The FAA basically picks a Boeing employee and says "you represent and answer to us now."

The employee however, is still managed, and reports first to Boeing management. They're a glorified liaison/paperwork interface. This was different than before as I understand it, because the FAA used to become the direct report for their Designated Engineering Representatives under the old system. This meant there was no management layer running interference between the rep and the regulator.

I might be misremembering that though.

I believe with AR even the picking is done by Boeing. unlike DER. One huge downside of this is that the informal interactions between FAA and Boeing engineers are almost non-existent, leading to even greater lack of technical knowledge on the FAA side.

>I can imagine some Boeing employees being uncomfortable, but having it run past the FAA would have relieved that.

There were some emails released where a Boeing employee boosted about he used "jedi mind tricks" on the FAA people.

It's not that shocking except in hindsight. The speed trim system is, from what I can tell, incredibly similar to MCAS at least on paper. They both adjust the stabilizer trim in order to ensure the legally-required amount of force is needed to move the stick in certain scenarios, both activate 5 seconds after the last manual trim input when flaps are up and autopilot is off, and both rely on non-redundant sensors. The only difference is the exact combination of sensors used and the exact obscure scenario they're designed to protect against.

Thank you for that explanation

I read here previously, I think it was here, that the primary difference was that after repeated counteraction by the crew the speed-trim system would give up, whereas MCAS doubles down and reduces the time between its attempts to force trim "correction", literally wearing pilots down physically until the system wins and the plane crashes.

Another post showed how AoA sensors (IIRC) has systematic errors causing MCAS to operate when corrections weren't required. As you say, lack of redundant sensors.

The term for this is regulatory capture. That is why staff at the FAA share in the culpability of these tragic events.

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