I think you will find that insurers, safety case authors etc are unlikely to have a 100% survival rate within their initial calculations. They tend to deal with worse case scenarios, acceptable loss levels and unacceptable loss in order to have an agreed level that would be acceptable risk and subject restrictions both operationally and management.

Not much discussion in this discussion forum on this topic so far. MB1, I agree but who sets these levels, who decides acceptability or otherwise and to whom are they acceptable? Marine insurers may anticipate x% casualties whilst public liability insurers may be horrified at anything approaching that figure for The Olympic Stadium. And what about planners for a new airport? A Kurdziel, judging by some posts on other threads, some H&S professionals will not tolerate any fatalities after a major safety failure, expecting an emergency plan to be perfect and perfectly executed. Media of course are there solely to promote their own agendas, whether it's to generate profits via advertising or increase funding from taxpayers. A horror story is great for that.

I don't think there can be any single criterium for a 'successful outcome'. Different situations represent different potential outcomes. For example, for an airliner at 34,000 feet suffering a major mechanical failure, any survival might be considered as acceptable. For a fire in an office any fatality might be considered unacceptable. And there will be a wide range of different 'successful outcomes' in between. In my view each particular situation will need to be considered on its own, recognising the potential of damage to or loss of life of those involved and of property, etc., and what practical measures are possible (a) to prevent the situation from arising and (b) to minimise any negative outcomes. Chris