A study of some factors influencing military parachute landing injuries.

In a retrospective study of 201,977 jumps, carried out by male military parachutists, over a 10-year period, landing injury rates were calculated according to the time of jump (day or night), the type of parachute, and meteorological data. Also, the wind speed, temperature, and the relative humidity at ground level were taken into account. The two types of parachutes used were both static line deployed, non-steerable canopies. The landing injury rate was found to be influenced by the darkness, surface area of the parachute, wind speed, and possibly temperature when higher than 25 degrees C. The influence of surface wind was best described by two segments of line with a cut-off point. The wind speed at the cut-off point is 12.75 k (6.56 m X s-1) for day jumps and 6.75 k (3.47 m X s-1) for night jumps.