Offshore installation safety cases came about from the Cullen inquiry into the Piper Alpha disaster and introduced the offshore installation safety case regulations in 1992. The current version of the regs is SI 2005 No 3117 and can be downloaded free at
Statutory Instruments 2005
The companies I've done work for, see workforce involvement as a critical element in safety case management. Offshore workers (the people who actually do the work) are involved in reviewing draft material for inclusion in the safety case. Major changes to hazards and risks are roled out to the workforce by means of summaries / posters / presentations etc.
Having been on NAEDIT in the mid 80s, if someone had bothered to ask what we thought were major hazards, each of us trade specialists (the workforce) would have been able to give a list there and then without too much thought, as I'm sure would the NFTC and GSU crews.
But as DV says it's all about people (and knowing the right people to ask).