Interesting thread to read.
With all the DDPG's available the aircraft should be able to fly with multiple defects. Commonsense should play a big part when something is not covered by it.
The line? Where do you draw it. Good question.
Is a reported missing life jacket in the cabin of a B747-400 full of fuel and punters just about to push back make the flight illegal?
Whats the other end of the scale.......