'Nuclear Might: Ready But Safe' is the name if this vintage US Air Force training film. It tells us what a "broken arrow" is: An accidental event that involves nuclear weapons, warheads or components, but which does not create the risk of nuclear war (Wiki). There have been a number of broken arrow incidents since the dawn of the nuclear age, and they haven't stopped since the end of the Cold War. Google it if you don't believe me. Sleep well tonight.