Trauma is a time-critical condition. Helicopters are thought to enhance the accessibility to trauma centers, but this benefit is poorly quantified. The aim of this study was to conduct a geographical analysis of the added benefit provided by helicopters, over ground transport. This study uses geospatial analysis. Helicopter bases and Level I and II designated trauma centers were geocoded. 60-minute drive-time and elliptical flight-time isochrones were mapped with ArcGISä (Esri, Redlands, CA). Calculations included allowance for mission ground time (MGT). We compared the proportion of the population that could be taken to Level I and II trauma centers, within 60 minutes, by road and by air. Using a 30-minute MGT model, helicopters permit 279,317 additional residents (5.8%) access to a Level I trauma center within 60 minutes. Using the 20-minute MGT model, 1,089,177 more residents (22.8%) would have access to Level I trauma center care. The benefits were marginally greater for access to Level I and II trauma center care. Helicopters enhance access to specialist trauma center care, but the benefit is small and dependent on MGT. Consideration should be given to the siting of helicopters, particularly in relation to trauma patients, MGT, and the timely response of EMS when determining the triage for helicopter transport.