<<You could even offer to appear in court as a witness in the event of legal action!>>
This is the ultimate HSE get out of jail free card [B]or[B] the one that ensures you have good company there.
Seriously, is H&S, if you are aware of something then you are also responsible be you the worker, his mate, his boss or THE BOSS. It immediately kills the 'I didn't know' excuse (decode I am incompetent).
As long as you pass it up the line your 6 is covered. But you must do it in a 'can do' manner and not a whinging 'can't do' manner. A stress shared is a stress halved, ask any bridge.
I had a great boss once in a job that was not obviously stressful just a regular 6 day week with 10 and 14 hour shifts. He was not around on the 14 hours shifts. I began making mistakes, a colleague brought this to the bosses attention, he had a word with me and saw that I got more rest for a day or so and less stress for a while. Careful management is needed at all times. Don't be too work focused.
The jet fell over, the training trip didn't happen. C'est la vie - it will never happen but another trip will come along.