I always used to sell the 'force multiplier' aspect of our helicopter! --A 15 minute flight in our helicopter could result in a road ambulance and crew remaining available in a rural location for many hours.
We averaged approx 45 minutes from 999 call to hospital over a 10 year period with a paramedic crew. A 'very fast' ambulance that could help both patient and the Service.
With doctor lead medical teams on a helicopter, the focus is often different.
The helicopter is used as a rapid intervention vehicle to get definitive medical care to the patient. Once stabilised it may now be better for the patient to be transported to hospital by road vehicle!
Several UK HEMS 'models' exist these days, depending on the composition of the medical team carried. Some 'traditional' but superfast blue light ambulances, others more like airborne surgical tools.
But I'll still want to know why a 6 car RTC, reported in to ambulance control only by the police, with no details of any casualties, is a HEMS job?