Abstract Background Prompt prehospital triage and transportation are essential in an organised trauma system. The benefits of helicopter transportation on mortality in a physician-staffed pre-hospital trauma system remains unknown. The aim of the study was to assess the impact of helicopter transportation on mortality and prehospital triage. Methods Data collection was based on trauma registry for all consecutive major trauma patients transported by helicopter or ground ambulance in the Northern French Alps Trauma system between 2009 and 2017. The primary endpoint was in-hospital death. We performed multivariate logistic regression to compare death between helicopter and ground ambulance. Results Overall, 9458 major trauma patients were included. 37% ( n = 3524) were transported by helicopter, and 56% ( n = 5253) by ground ambulance. Prehospital time from the first call to the arrival at hospital was longer in the helicopter group compared to the ground ambulance group, respectively median time 95 [72–124] minutes and 85 [63–113] minutes ( P < 0.001). Median transport time was similar between groups, 20 min [13–30] for helicopter and 21 min [14–32] for ground ambulance. Using multivariate logistic regression, helicopter was associated with reduced mortality compared to ground ambulance (adjusted OR 0.70; 95% CI, 0.53–0.92; P = 0.01) and with reduced undertriage (OR 0.69 95% CI, 0.60–0.80; P < 0.001). Conclusion Helicopter was associated with reduced in-hospital death and undertriage by one third. It did not decrease prehospital and transport times in a system with the same crew using both helicopter or ground ambulance. The mortality and undertriage benefits observed suggest that the helicopter is the proper mode for long-distant transport to a regional trauma centre.