One hundred twenty-six consecutive ACS Category I motor vehicle trauma patients transported by helicopter from 25 hospitals to a regional trauma center in rural Pennsylvania during a 14-month period were reviewed retrospectively. The overall mortality was 13%. Average round-trip distance was 79 miles. Interventions by the medical flight team (emergency physician/nurse) included endotracheal intubation, tube thoracostomy, and/or central venous access in 42 patients (33%) prior to lift-off. Ground time at the referring facility, from landing to lift-off, when no interventions were required of the flight team, averaged 31.2 minutes (baseline). Ground time when major therapeutic interventions were required (principally airway management), however, averaged 57.4 minutes, an 84% increase over baseline (P less than .01). A major cause of the excessive ground times was the lack of standardized diagnostic workup and stabilization of patients prior to arrival of the flight team. Recommendations for standardized emergency department preparation of trauma victims requiring aeromedical evacuation are made.