Oh wow, has this thread descended to the point of being little more than a cesspool of misinformation and poorly drawn conclusions based on misunderstandings of how the industry works and misguided attempts at trying to draw parallels to industries for which no parallels to aviation exist.
Such a face-palm of a thread that just goes to show that most "enthusiasts, FFs, avgeeks, etc" have a hard time understanding the significant subtleties of the aviation world, how it is regulated and how aviation operates within those regulations.
That being said, there are a couple of buried nuggets of accurate information in this thread, but some of the conclusions drawn are inaccurate or incomplete.
There is no more of an inherent instability of the 737Max design than there is for the 737NG. The handling characteristics of the Max can be quite different than the handling characteristics of the NG under similar flight conditions.
The real crux of the issue is the desire (by the airlines) for the Max to have the same pilot type rating as the 737NG aircraft. This means that a pilot flying a 737NG would have the same feel is if they were flying a 737Max and vice versa. I guess an analog many could relate to would be making driving a motor-coach bus feel them same as driving a city-bus. This common type rating means that airlines do not have to maintain different pools of pilots which means greater operational flexibility and cheaper operation costs for airlines. The idea was a NG pilot could start the day in an NG, finish the day in a Max and not notice any difference.
There's just one problem, it is physically impossible to make flying the Max "feel" like flying a NG, the larger diameter, further forward engines will make the handling characteristics (the feel) quite different than the NG. Enter MCAS, a good idea that probably should have never seen the light of day, an idea I have fundamental issues with (I'll explain) and issues with its implementation, which I'll also explain, as the two are not related. IMHO, the Max should not have been given the same type rating as the NG, but here we are.
MCAS - I have an issue with its purpose: It goes against the basic Boeing philosophy (Airbus & Boeing have differing philosophies related to control authority) which is that the pilot always has final control authority. MCAS is the opposite of this, and instead of proverbially saying "human this is happening, do something" it just takes an action and does not inform the pilot, which is more of an Airbus type of control philosophy.
MCAS - my issue with its implementation: All systems require a SFHA (System Function Hazard Analysis), Boeing has stated that the MCAS was rated hazardous, which means it is classified as a DAL-B (Design Assurance Level B) system, DAL-B systems have to meet a failure rate of 1e-7 per flight hour or less. I have personally performed more than a dozen SFHA's and supported a half dozen more, I can not for the life of me figure out how a DAL-B system can rely on a single sensor and would love to see what the other mitigating conditions Boeing listed for the MCAS SFHA that permitted its reliance on a single sensor.
Now the regulation piece that a lot of people seem to be jumping on, there is no "Fox in the hen house". It is an industry norm where the OEMs have their own specifically designated people perform some of the certification work, I performed that function myself as well for several aircraft systems. However, the FARs (regulations) still apply, and those OEM designated people need to follow and enforce the FARs, in fact, we are empowered to do so by law. In addition, the FAA (as well as EASA, CASA, TCCA, etc) are supposed to ask the OEMs to prove that their engineering and safety attestations are accurate, valid and in compliance with all applicable regulations.
So when it comes to MCAS, Boeing made some assertions, did the FAA challenge those assertions? That is really what I am waiting to see.
As for all the discussions regarding software engineering etc - oh man, just so much lack of understanding about how aviation software and systems are designed and tested. All I can say is read up on DO-178B/C and DO-1254 before any sort of intelligent discussion can be had on that topic. Suffice it to say, that until someone has worked on the design and testing of an aviation system, they will have no understating of just how complex, comprehensive the ordeal is and how every line of code can be traced back to a requirement that is tested against.
Now for the Air Canada spin on all of this. Air Canada did not have any type 737 rated pilots, so the training that AC pilots received for the Max is the complete several weeks long training that all new type rating pilots have to receive. In addition, it is the operator that defines and creates the pilot training programme, not the OEM. The OEM provides a room full of binders which comprises the owners manual, and it is up the operator to read the owners manual and create the pilot training programme, just as you receive an owners manual when you purchase a car. GM, Ford, Toyota, Honda, etc do not teach you how to drive/operate your car, same goes for aviation.