The irony is that an ad-hoc SAR letdown to a rescue in the vicinity of Blacksod would have been completed much nearer to the intended destination, would not have required an extensive crew brief or the use of approach plates and would have been much safer.
Back to the company procedures that were not fit for purpose......
I agree that ad-hoc SAR ARA letdown is sometimes the simpliest way to reach the destination, but here... with all respect Crab, we can't blame the routing that much... I can only refer the Preliminary Report 3.5.8. Operator's Route Guide. If the pilots read and understood the guidance and had flown the vertical profile accordingly, there shouldn't have been problems. Operator's Route Guide gives the hight of Blackrock 310 ft. It is on pilot's discretion how (at what altitude/height) he/she is going to pass the waypoint BLKMO (it could have been 1300ft or even 2000ft AGL). Now, for some reason R116 had already descended to 200 ft RHT (AGL) when they still were west of the BLKMO waypoint... (Of course we don't know for sure, what kind of approach briefing they had in cockpit... VMC or IMC?)