It is important to understand that both Boeing and the FAA are bureaucratic stovepipe organizations where information and responsibility is retained within disciplines. Finding compliance to a particular paragraph in the FARs is parsed out to individual UM/ARs who put together and approve the certification documents. These myriad of certification documents, where I remind you has MCAS interspersed, had been drafted and mostly completed at the time the MCAS Rev D revision. At the the time of the Rev D revision, the task before the UM/ARs would have been whether the change in functionality to include the low speed flight envelope necessitated changing these certification documents. When the erroneous activation of MCAS is judged as “Hazardous” which the FAA permits Boeing to make without outside oversight, it ensures the FAA does not gain visibility of the system and for its functionality to not be mentioned in the certification documents.
Mark Forkner in his role as Chief Technical pilot represents the services business of Boeing and not the design and manufacturing business of Boeing. It may be that the 737Max Flight Control engineers who developed and approved the Rev D revision considered whether the change in functionality required changing pilot training. It one sees the MCAS failure as equivalent to a runaway stabilizer trim one could conclude that there would be no impact to the training curriculum. That conclusion though is not Boeing’s to make exclusively of the FAA which is why Forkner and Boeing is found criminally negligent.
Let’s not forget that when Boeing concedes that additional simulator training is required for the 737Max for return to service that this training recommendation applies to all 737 models. The actions by both flight crews indicates an incomplete understanding of elevator, horizontal stabilizer and its systems.
The biggest problem with the argument you present is that common sense does not apply.
I asked some people who work in development of code in various industries what happens, and every single one of them says you write some code and counter check at every stage whether it meets requirement for the task it seeks to accomplish. After all of this is done, you look to stress test it to ensure that when it gets to market, that the software will not run into issues.
Some established checks include the people writing code (maker) not being the same people counter checking (checker) and analyzing that code on the next step in quality analysis. You might more layers before the product is validated, and all of these exist to catch problems between code development all the way to code deployment and the behavior of that software in real world conditions. In aviation, this is during certification.
JATR and the Committee on Transport reports show just how people did not either care about their jobs at the FAA and Boeing and how the latter simply wasn't bothered in getting things done the right way. People signing off on things they do not understand, people raising questions not being heard, proper controls not being in place at either organization, and overall, people not understanding how small mistakes, lapses in judgment and/or a lack of testing all compound into huge mistakes. If people were checking, they would have caught the fact that some testing had not been done, from testing, they would have realized that there was the potential for catastrophic loss of life in the real world and that their assumptions were incorrect.
We talk about MCAS and fixate on it, but as previously stated, it was not the only thing that could have led to the plane crashing, it was simply the first thing that led to two hull losses with no survivors. The more regulators checked, the more problems they found, and even after clearing the jet, they still found issues that needed to be corrected.
If the issues were isolated to this one product, one might be fine with it and state that it was an isolated incident. However, we have pickle fork issues on the NG which are likely to translate to the MAX because they share the same platform. You have issues with the Dreamliner, some issues may apply to the global fleet (how that gets handled is another issue altogether), Boeing having had data and just never bothered to check. You have issues with on the military and space side of things too while the 777X has run into regulatory issues.
MCAS being interspersed, Boeing not correctly classifying MCAS, all of these are domestic issues at Boeing.