| Helmet mounted displays (HMDs) are becoming common human-machine interface equipment in manned military flight, but introducing this equipment into the overall aircraft escape system poses new and significant system design, development, and test concerns. Although HMDs add capabilities, which improve operator performance, the increased capability is often accompanied by increased head supported mass. The increased mass can amplify the risk of pilot neck injury during ejection when compared to lighter legacy helmets. Currently no adequate US Air Force neck injury criteria exist to effectively guide the requirements, design, and test of escape systems for pilots with HMDs. This research effort presents a novel method to develop neck injury criteria to aid the design and test of future HMD-centric escape systems. The state of the art pilot-scale injury criteria risk functions developed in this research are constructed with combined human subject and post mortem human subject experimental data using a parametric survival analysis. The resulting neck injury criteria permit injury risk and classification levels specified by the Air Force escape system oversight office to be translated into system level test criteria. The application of the system level criteria during developmental and qualification testing of escape systems will ensure pilot safety and limit risk of neck injury. A Human Systems Integration analysis of the HMD trade space is also performed to demonstrate the importance of neck injury criteria and other tools to quantify the human-centric costs and benefits during HMD development. |
