Stone KL, Smedley WA, Killian J, et al. - Researchers investigated how different flight path models influence the calculated population coverage of aeromedical retrieval systems, using the state of Alabama as a case study. They performed a geospatial analysis of US Census Bureau population data employing helicopter bases and trauma centers as foci of either circular or elliptical coverage areas. Circular isochrone models around helicopter bases or trauma centers imply that a level I or II trauma center could be reached within 60 min by the entire population of Alabama. Elliptical isochrones, incorporating outbound and inbound flights, imply ready access of only 78.8% of the population to level I or II trauma centers. All three flight path models are identified to have some validity and utility, however, simplistic circular flight time isochrones around trauma centers and helicopter bases afford overly optimistic estimates of population coverage. The elliptical model affords a more practical evaluation.