Donut King,
I think Nick is saying that the baseline is this:
The manufacturer provides a procedure that has been shown to work to provide aircraft and occupant safety. If a company or individual see fit to operate outside the parameters provided, the buck stops there.
Seems to me that if an aviation authority requires a procedure or regulation (such as Cat A / Class 1) to be complied with it does becomes mandatory if the aircraft is flown under the auspices of that authority!
The best piece of advice I was ever given was "what would a board of inquiry think about that?"
At the end of the day, it might well be decided in court in the worst case.
Certainly the UK CAA have pursued a prosecution for perceived breaches of safety. I know of one case where a heli pilot was prosecuted and fined a considerable sum because he flew at night without navigation lights illuminated. This occurred because a circuit breaker had popped. The pilot was apparently reported, but not advised of the failure of his lights, by ATC at the heliport from where he departed! But that is another story.......
