Injuries to Post Mortem Human Surrogates in Oblique Aircraft Seat Environment

Increased interest in the airline industry to enhance occupant comfort and maximize seating density has prompted the design and installation of obliquely mounted seats in aircraft. The potential for injury and their mechanism in this seating environment is unknown. Epidemiology-based field injury data do not exist for airplane crashes, however, typical impact scenarios have been determined and safety standards addressing fore, aft, and side-facing seats have been levied by the FAA. The impact scenarios defined in these standards can be used to study likely injuries and injury mechanisms using Post Mortem Human Surrogates (PMHS) in a controlled laboratory environment. Four PMHS were seated upright with Frankfurt plane horizontal in a custom designed seat configured to simulate potential aircraft environments and candidate restraint geometries. A scaled Part 25.562 Emergency Landing condition for horizontal impact was used as the dynamic test input. High speed video recorded occupant kinematics. Pre and posttest x-rays and CT’s were obtained and autopsies were conducted. Severe injuries to the cervical, thoracic, and lumbar spine were observed in three of the four specimens and attributed to torso flail. Pelvis injuries likely caused by the seat belt were found in two tests. Multiple rib fractures were also seen, caused by contact with arm rest or other body regions. The fourth test was run at a lower severity and did not produce injury. This suggests a conservative threshold for human tolerance to this loading environment. Although the study is of a limited sample size, it suggests the need for further testing to develop standards that provide similar levels of safety for obliquely mounted seats as forward/aft facing seats in aircraft.