Of course, one of the problems created by modern management is that they don't give specific instructions. they just create an atmosphere where things can be done in a different way.
The best example is the 2011 breaking of the phone hacking by Murdoch (and other) newspapers. It seems (at this stage of the investigation) that there is no smoking gun. No one was
told to hack phones but people have stated that they
knew that was what was wanted. Given that, as it was being done, the mgmt did not stop it ...
That is the problem and you will not track it down to clear instructions because clear instructions can be tracked back. If the rules are unchanged but practise HAS changed - when it all goes wrong, then the boss can point to the person who broke the (still standing) rules.
On the above example of reverse at BKK. One can readily imagine the mgmt saying: "Yes, we did say to keep use of reverse thrust to a minimum to save engine wear BUT we did not say to do so to the point where you ran off the end of the pavement."
Simples.