That type of Human External Cargo (HEC) ops are used by various SAR operators around the world. That is especially true in territories where utility aircraft that are normally used for placing structures or equipment inch-perfect in wild or mountainous country are also used during SAR operations. It can be used to insert rescue personnel to an accident location. In at least one territory, air ambulances maintain the capability to insert a paramedic to the accident locations, where the aircraft cannot land, using this method.
However, at a number of ICAR Air Commission meetings, HEC accidents have been far too prominent a part of the proceedings. Engine failure, collision with obstruction, inadvertent IMC, and attachment mistakes all played their part.