FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-15/17

Title and Subtitle: Effect of Passenger Position on Crash Injury Risk in Transport-Category Aircraft

Report Date: September 2015

Authors: Taylor AM, DeWeese RL, Moorcroft DM

Abstract: In the event of an accident, one action that an occupant can take to contribute to their survival is to assume an appropriate brace-for-impact position. This is an action in which a person pre-positions their body against whatever they are most likely to be thrown against, significantly reducing injuries sustained. Occupants in the US Airways Flight 1549 sustained shoulder injuries that they attributed to the brace position; therefore, the NTSB recommended that the position be re-evaluated.

The Federal Aviation Administration investigated this by conducting a series of 17 sled impact tests, 15 with two rows of transport category forward facing passenger seats and two with a bulkhead configured to represent the types of seats currently in use. Head, neck, upper and lower leg injury risks were evaluated using an advanced test dummy and injury criteria from current FAA regulations, Federal Motor Vehicle Safety Standards, European auto safety regulations, and applicable research findings.

The current brace position, head against the seat back with hands on top of the seat back, was only successful in reducing head injury risk for locked-out seat backs. However, for full break-over and energy absorbing seat backs, this position increased the severity of the head impact. There was, however, no evidence that the anthropomorphic test device interaction with any of the seatback types resulted in hyper-extension of the shoulder joint. Significant lower leg injury potential was not observed in this study, and therefore adopting lower leg injury criteria at this time does not appear to be a benefit.

Even in the worst case test condition, the femur axial compressive force was below the regulatory limit, indicating that the femur compression criteria currently cited in FAA regulations is not likely to be exceeded in passenger seat dynamic qualification tests. To reduce detrimental interaction between the occupant's arms and the seatback, the current position was modified by placing the hands down by the lower legs instead of on the seat back. This alternate position was successful in significantly reducing head and neck injury risk for all of the seat back types evaluated.

This research has led to the determination that as seat technology has evolved, the most effective brace position has as well, and the current positions recommended in AC 121-24B may need some adjustment to provide an equivalent level of safety for all passenger seat back types.

Key Words: Brace for Impact, Passenger Position, Leg Injury Criteria, Neck Injury Criteria, Head Injury Criteria, Femur Compression, Femur Bending

No. of Pages: 42