 Whilst some air ambulances do have effective methods of funding, in the UK, they remain almost entirely charity funded, as improved cost-benefit ratios are generally achieved with land-based attendance and transfers.Health outcomes, for example from London's Helicopter Emergency Medical Service, remain largely the same for both air and ground-based services.The medical personnel of a helicopter ambulance has historically been a Physician/Nurse combination, Paramedic/Nurse, or a Nurse/Nurse combination.