From the invention of planes until the 1980s (or thereabouts) it was all about protecting the passengers and pilots from the plane itself. But technology and automation made the planes increasingly and exceptionally safer. From the 1980s to the early 2000s (until 9/11 really) it was then about protecting the plane and pilots from certain passengers - specifically hijackers. Now, it’s pretty clear that as passengers are better screened and as the planes have become even more reliable, the only risk that is left is pilot error or sabotage. We need more supervision/automation that protects the plane and passengers from the pilots. It’s a narrow failure mode that is unrecoverable but totally avoidable.