DETERMINING AIRCREW HELMET SIZE DESIGN REQUIREMENTS USING STATISTICAL-ANALYSIS OF ANTHROPOMETRIC DATA

Traditionally, the number of aircrew helmet size rolls has been determined using head length and breadth for specified percentile ranges of a target population. Helmet mounted display technology will require taking the third dimension (pupil-vertex height) into account. Using data from "An Anthropometric Survey of 2000 Royal Air Force Aircrew, 1970/1971", the three head dimensions of length, breadth, and pupil-vertex height were plotted for each subject. A minimum number of helmet sizes was calculated to achieve a reasonable quality of fit. The 93.5% of subjects grouped around the population mean was the largest fraction which had a reasonable quality of fit while using nine sizes. Attempts to fit a larger percentage would require either a large increase in the number of sizes or a relaxing of fitting quality.