Comparison of Injury Incidence in Two Different Military Parachuting Systems During United States Army Airborne Training

Abstract

The United States (US) Army is currently implementing a new parachute system (T-11) that will replace the older system (T-10) in use since the 1950s. The T-11 has a larger canopy resulting in a slower decent rate and reduced kinetic energy on ground impact. Due to the recent release of the T11, no previous study has systematically compared injury rates between the two parachute systems. PURPOSE: This analysis compared injury incidence between the T-10 and T-11 military parachute systems. METHODS: Participants were students in Airborne training at the US Army Airborne School, Ft. Benning, GA, between 15 March and 15 September 2010. Over a one week period, students performed their first jump with the T-11 and several subsequent jumps with the T-10. Injury data was collect from Jump Closure Reports obtained from the Airborne School. Combat loaded jumps and night jumps were excluded since these were only conducted with the T-10 and previous studies have indicated that these types of jumps elevated injury risk (Knapik, Aviat Space Environ Med 79:408, 2008). Predictive Analytic Software version 18.0 was used to perform a chi-square analysis comparing injury incidence between the two parachute systems and to calculate a risk ratio (RR) and 95% confidence interval (95%CI). RESULTS: There were 21,404 parachute descents with the T-10 and 9,351 descents with the T-11. Injury incidence was 2.57/1,000 descents with the T-10 and 1.39/1,000 descents with the T-11 (RR [T10/T11] =1.85, 95%CI=1.03-3.52, p=0.04). CONCLUSIONS: One limitation to this analysis was that students had more jump exposures to the T-10 system than to the T-11 system. In addition, the T-11 was used on the first jump among students who had never before performed a parachute jump. Nonetheless, the data strongly suggests that injury incidence is lower with the T11 parachute, compared to the T-10 parachute, when Airborne operations are conducted during the day and without combat loads.