The evacuation of persons (usually by air transportation) to a place where they can receive medical care WordNet 3.0 & Open English WordNet

Medical evacuation, often shortened to medevac or medivac, is the timely and efficient movement and en route care provided by medical personnel to wounded being evacuated from a battlefield, to injured patients being evacuated from the scene of an accident to receiving medical facilities, or to patients at a rural hospital requiring urgent care at a better-equipped facility using medically equipped air ambulances, helicopters and other means of emergency transport including ground ambulance and maritime transfers Examples include civilian EMS vehicles, civilian aeromedical helicopter services, and military air ambulances. Wikipedia

Evacuating a patient by plane or helicopter or even train Wikipedia Disambiguation

A vehicle, typically aircraft, used for emergency transportation of patients to a medical facility. Wiktionary