Break up of airplanes
I just watched the "documentary", and I didn't see anything that convinced me that the airplanes break apart due to a design or construction flaw.
I have absolutely no background in the field except from breaking a lot of stuff in my younger years. (cars, bicycles, toys, my dad's unbreakable watch which i proved was an inaccurate statement etc).
An airplane is not built for off road excursions.