While the helicopter was performing an underslung load operation at Loch Scadavay the boat it was carrying became unstable and flew upwards, causing the lifting line to strike the helicopter’s tail rotor. The helicopter became uncontrollable and descended rapidly into the loch, fatally injuring the pilot. The physical characteristics of the boat and the method by which it was carried increased the probability of it becoming unstable. The helicopter operator has taken a number of safety actions mainly relating to its operational procedures and training. It has also temporarily curtailed the carriage of selected types of unstable or potentially unstable loads.