Safety Cases & Risk Assessments reared their ugly head during the latter years of me being an ATCO. I well remember being asked to carry them out (the whole unit never having done one before). We asked the SRG for guidance on what had to be done & how to do it. Their response ? None ! (other than that we'd have to find out for ourselves -which we did with the help of EGSS SATCO/Chief Officer).
Prior to that, ATC adopted a "Fail Safe" Approach.ie if the Radar failed, & separation was likely to be compromised, then it would have to "fail safe". This was built into separation standards etc. & applied to the whole range of ATC procedures in this, & other areas.
Safety Cases & Risk Assessment don't quite fill me with the same sense of confidence in the system, somehow. It's not so much that they don't Guarantee a safe system subsequent to the failure; but, that they seem to assume that there WILL BE NO failure !
It's not just ATC. Just look at ETOPS operations. I accept that there have been no disasters (for which I am exceedingly thankful ; although there was a very near miss in the Azores with the TSC EA33; but, how can Risk Assessment & Safety Cases guarantee that there never will be ?
And IF there ever are any, no amount of Safety Cases & Risk Assessment exercises are going to avoid them !