Re: Range Safety
"If the engines had failed and they lost control, one of the jobs of the Range Safety Officer is to remotely detonate the vehicle"
And, the RSO should not need to get any approval to do that. It can be prudent in some instances to hold off on blowing it up, but shutting off the motors and letting it get clear of some islands first and then create a load of multi-colored rain. What to do when depends on the circumstances. One big lump might be preferred if the splash down point is away from everything rather than a wide area of smaller chunks.
I've stood by with a Big Red Button before. In our case, the rocket wouldn't be blown up, but a lot of valves would be immediately put into their default state which would cut pressure and vent tanks. We held planning meetings on where, when, who, how. For most flights, there would be two of us with kill-switches looking on from opposite sides. The flight director could also call out dropping the vehicle if he could see that control was lost and the rocket didn't do it automatically.
There were two "fences" for the landers I worked on. Breaching the first fence should have had the rocket land immediately and violating the second fence would kill the engine and vent the tanks. Humans were in the loop in case the software wasn't right. I can recall only one time where the first fence was violated and that was due to a programming error by the GN&C engineer and led to a new and mandatory flight profile checklist. The lander rose up 50cm and landed itself. Very not good.