Analysis of extrinsic factor associated with 379 injuries occurring during 34,236 military parachute descents.

A retrospective study of 34,236 consecutive static line parachute descents by trained parachutists, in which 379 were injured, is described. Injury rates associated with extrinsic factors were compared and then analyzed using logistic regression. A table describing the association with extrinsic factors, with relative risks, is at Annex A. The overall injury rate was 1.11% (1.11 injured per 100 descents). Rates from Helicopter (0.20%) and Balloon (0.13%) were low, and the study thus concentrated on aeroplane descents (injury rate 1.46%). Extrinsic factors associated with increased injury rates were carriage of equipment; wind speed and direction; numbers exiting and (on logistic regression) night descents. The overall rates appear higher than expected, possibly due to equipment weight potentiating the other factors. A prospective study is required to investigate the effect of equipment weight after which peace time training constraints should be reviewed. (Two approaches are described.)