PART 1
In the interest in moving the conversation along, and in particular to help transition this thread from a rearview, reactive mode to a more forward-looking proactive one, I would like to tee up a subject that is hopefully familiar to many aviators - the Threat and Error Management Model. I have some more thoughts to share that build upon this model, so it would be helpful to have some familiarity with it.
Briefly, the TEM model examines aviation safety through a lens that assumes that pilots will always be faced with threats (known and unknown) and errors. It is assumes that there are no perfect aircraft, environments or people, but it tries to devise a resilient system that is capable of identifying and mitigating threats and trapping errors. Rather than cut and paste a full description of the TEM model, I would ask you to look at the links below:
Introduction to Threat and Error Management
Wikipedia Threat and Error Management
Part of the TEM model is the concept of
barriers. Barriers are those things that can be put in place to mitigate threats and trap errors. Some people refer this to the "Swiss Cheese" model because it assumes that no barrier is perfect either. Even though there will be holes in each barrier, the concept is to have enough of the right type of barriers so the "holes" do not line up and lead to either an undesired aircraft state or worse, an incident or accident.
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The MAX accidents can be analyzed using the TEM model to identify not only the particular threats and errors, but also whether there were sufficient barriers and/or why the existing barriers did not ultimately prevent these accidents. Armed with this information, then the goal is to identify how those barriers can be improved to prevent future incidents and accidents.