hog driver...
Multiple layers of safety redundancy have been eroded to let the “Golden BB” through the Swiss cheese. It appears that no matter how many safety devices can be installed we are still only human.
When I began in radio news nearly 50 years ago, MAC's were not that all uncommon. Look at it now: how often do they happen? The holes aren't lining up as often anymore, not nearly as much as when I began.
(Note: I have never used anything on PPRUNE in my job; I'm here solely because I lived next to an airport, my father worked in the Corsair plant, I worked in the Sikorsky plant, and two of my neighbors were pilots.)