Air Evac EMS, Inc., operating as Air Evac Lifeteam (sometimes known as simply Air Evac), is the largest company within (Air Medical Group Holdings). Air Evac is still the largest independently owned and operated HEMS (Helicopter Emergency Medical Service), or air ambulance provider. Air Evac currently operates helicopters at 131 bases, covering most of the central and southern states; Service Area. While primarily a HEMS provider, they do operate 2 fixed-wing aircraft in Missouri and Kentucky. Originally based in West Plains, Missouri, the headquarters, dispatch (CenComm), and a few other departments were moved to a new facility in O'Fallon, Missouri in 2013.