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A study of the biomechanical factors concerned with the design of side structures and doors for crashworthiness has been made. Questions regarding optimum stiffness, location of reinforcing members, effect of armrests, and padding have been answered within the framework of injury criteria models. Results of animal studies, cadaver studies, and anthropometric dummies have been combined to produce injury criteria for lateral impacts to the head, thorax, and abdomen. Impacts were applied utilizing a specially designed “air gun” in a laboratory environment emphasizing reproducibility and control. Full-scale crash simulations were performed on an impact sled to verify the results of the more specialized tests and analyses. Scaled models of current production doors were used in the animal series. Scaling relationships for various species of animals have been developed and extrapolated to man. Significant differences in right and left side tolerances to impact were noted and detailed.

Human impact injury and survival tolerance levels for various crash conditions are presented on the basis of currently available biomedical and biomechanical knowledge. Consideration of physical factors influencing trauma-including body orientation, restraint system, magnitude, distribution, and time duration of deceleration-are summarized, as well as tabulations and sources of data for both whole body and regional impact tolerances. These biological data concerning human impact tolerances are provided as guidelines for improved engineering design of general aviation crashworthiness.

Aircraft used for business (executive corporate transportation or personal business) and utility purposes now represent about one-third of the total United States aircraft inventory. Data from accident investigation of business aircraft involved in survivable accidents indicate serious injuries and fatality to the occupants occur most frequently as a result of the unprotected head and neck or chest flailing in contact with aircraft controls, instrument panel, or structure. Improvement of current aircraft to provide increased occupant safety and survival during crash impacts is both necessary and feasible. Design considerations include folding seat back locks to prevent collapse, increased seat tie-down to structure, instrument panels and glare shields designed to absorb energy through structural design and padding, stronger seat structure, lateral protection, design and packaging of knobs and projections to minimize injury in contact, and installation of upper torso restraint.

Although it has been well established that the lap (seat) belt offers considerable protection against injury or death in crash environments, there has long been controversy over the injury potential to the pregnant female. This question is of importance in consideration of restraint and seat protective environments for both aircraft and automotive vehicles. Most of the 4 million pregnant women per year in the United States travel by automobile, with a large number traveling by Commercial Civil Aircraft or the Military Air Transport Service. Thus a sizeable population is involved. This combined study by the Civil Aeromedical Institute, F. A. A., 6571st Aeromedical Research Laboratory, Holloman AFB, and the University of Oklahoma School of Medicine, has been concerned with the clinical, experimental, and applied aspects.