In the North Sea my understanding of the system was a Medevac heli flight was used to evacute walking wounded,back to an ambulance at the airport.A Casevac was life threatening and usually flew straight to hospital.Both were put on the flight plan to assist ATC,but not used in the callsign.The heli companies had a special flight number for those flights
The SAR helis use a Rescue callsign in similar situations,and an Airliner with a medical emergency that serious should declare an emergency(Pan or Mayday).
However it is the sandpit.
