Aircraft crash survivability from viscous injury in vertical impacts

This research investigated viscous injury from vertical impact loading to determine if it is critical to survivability of aircraft accidents. A unique database was built from autopsy reports and accident investigations combining injury data with the vehicle impact data. Computer models were created and used to assess injury potential. Common design limits and actual crash data from full scale research experiments were used as inputs. The results were analyzed according to published injury thresholds and compared with real accident autopsies to determine the validity of the hypothesis. Heart and Aortic Injury (HAI) has been considered a critical survivability factor through out the history of mechanized transportation. The mechanisms of HAI in the aircraft environment were never well characterized. Automotive research identified important HAI injury mechanisms related to the forward and lateral impact vectors. This research investigated the vertical impact vector. A model was developed to evaluate the biomechanical response of a simplified visco-elastic system, and incorporated into a system model which included the occupant and aircraft seat. This approach was similar to the development of spine injury criteria and provided the advantage of a macro level evaluation of the injury thresholds and assessment of the criticality in survivable accidents. Evaluations of real accidents sustaining HAI characterized a range of impact severity and approximate boundaries for survivability with HAI and internal organ injury. Viscous injury potential from vertical impact was found to be less critical than potential spine injury. Detailed analysis of HAI documented in autopsy reports and the corresponding accident investigations found that HAI was associated with cockpit environmental factors rather than inertial displacement mechanisms. Vertical displacement of the heart due to inertial loads is not a critical factor in survivable accidents given current aircraft technology. Inertial loading to the heart and aorta is a contributory factor for viscous injuries in aircraft accidents.