how could they know but nobody else did? Did they buy the extra sensor or something?

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    $\begingroup$ I'm not really understanding the question here. MCAS wasn't a secret, so I'm not sure it's surprising a regulator was aware of its existence. There are certainly arguments that regulators didn't scrutinize it enough, that pilots weren't given enough training on it, etc... but it's not as if the Brazilian authorities were the only people to know of its existence. $\endgroup$ Dec 31 '19 at 10:26
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    $\begingroup$ @ZachLipton from what I know, reading the many articles that have been published by the media, pilots nor airlines knew about MCAS. $\endgroup$ Dec 31 '19 at 11:25
  • $\begingroup$ Some pilots didn't know about it, or didn't know enough about it, and there's considerable question about Boeing hiding the reality of the system from regulators, but that's different than the basic existence of the system being a secret. Boeing at the time was "jedi-mind tricking regulators into accepting the training that I got accepted by F.A.A," essentially convincing regulators that while the system existed and was certified, it didn't need to be included in the pilots manual or differences training. $\endgroup$ Dec 31 '19 at 17:48
  • $\begingroup$ And the document you've posted is exactly part of that process. MCAS is listed as a difference between the 737 models on the Operator Difference Requirements, and regulators have a whole process where the manufacturer demonstrates the significance of each difference and the level of training required for pilots on the change. $\endgroup$ Dec 31 '19 at 17:54

Of course the airlines knew about MCAS. Do you think the maintenance manuals, maintenance program documents, tech training, wiring diagrams, and all that stuff was left out so it was totally top secret? There would be a controller, wiring and software on board even though there were no cockpit indications or controls, so certainly the techs who might have to troubleshoot it, and others on the tech/engineering side, would know.

All that happened was MCAS was excluded from differences training, as that document shows, so that it was not included in the ground school differences course pilots took when moving from one 737 model to another (avoiding sim time, which was the point).

So pilots never got a formal briefing on its existence, and it could just be considered part of the "PFM" of the various black box systems who's level of function is too in-depth to be included in pilot training (PFM means "Pure F-ing Magic" and is a term instructors use to describe black box function that is beyond the training because covering it would extend the course to months).

I have little doubt there were pilots, those who dig into the aircraft more deeply than most and might even peruse maintenance manual descriptions, who would have known of the system, but just not on an official level, with official procedures and protocols that affected the flight crew.

Sort of like the subsystem that applies the brakes after you lift off to spin the wheels down right away. It just does its thing in the background, and pilots may or may not be aware of it, but everybody on the technical side does.


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