There is a definite need for HEMS even in densely populated areas but I think there is also a case for screening what it is used for TIME/DISTANCE Where a land based unit can get to the scene in the same time ultimately the land based unit will be with the patient quicker due to the set down time and checks that a HEMS unit has to go through, plus where they can set down relative to an incident. No real use in built up areas because there is no where nearby to land. As Paramedics become more highly skilled and have a larger arsenal of drugs and techniques to use time on scene is less important as we can stabilise at scene (IV Fluids intubation etc) and therefor viability on arrival at an appropriate hospital, Major Trauma, Neurosurgical etc is improved. Main uses are RTAs and any sort of outdoor activities Horses, Motorcycles, Water sport etc. Sorry for a long reply.