Looking at the LKP on the larger scale map of post #115, it appears to be on the N side of Blackrock. Also the pic in post #140 shows the helipad to be on the N side of the lighthouse - which would be consistent with the turn NW then turn ESE to approach the helipad. The weather reports from the nearest stations suggest that conditions around Blackrock would have been a cloud base around 200-300 ft with visibility reduced in RA/DZ and a SW'ly wind around 20kt. As a meteorologist, a stable SW'ly airstream of that strength passing over an obstacle such as Blackrock would have produced a severe downdraft on the N side of the rock (like a 'hydraulic jump' airflow) - in such situations I've known of 10 metre yachts to be flattened or even dis-masted. So if they were below the 300ft summit of the rock (perhaps with the intention of climbing to approach the helipad IFR in cloud) the downdraught conditions below the cloud base on the N side of Blackrock could well have been very difficult even for a S92.