http://www.nytimes.com/1991/09/15/us/screws-missing-on-tail-wing-of-plane-in-crash-fatal-to-14.html http://www.nytimes.com/1991/09/15/us/screws-missing-on-tail-

http://www.nytimes.com/1991/09/15/us/screws-missing-on-tail-wing-of-plane-in-crash-fatal-to-14.html http://www.nytimes.com/1991/09/15/us/screws-missing-on-tail-... Sure a missing screw on a passenger seat is unlikely to cause the airplane to crash. Any redundancy can fail at critical moment.