A Biomechanical Investigation of Cervical Spine Range of Motion for UH-60 Aviators in Real and Simulated Flight Environments

Introduction: Military flight surgeons evaluating aviators for flight fitness based on the cervical spine range of motion (CROM) have no operationally relevant reference with which to make a reliable determination. The published physiological limits for the general population do not necessarily apply to military aviators. CROM requirements for rotary-wing aviators would ideally be defined by measurements taken directly within their operational environment. Materials and Methods: Nine subjects performed the same predetermined 1-hour flight mission in a UH-60 aircraft and then, at least 2 days later, in the U.S. Army Aeromedical Research Laboratory (USAARL) NUH-60 flight simulator. Head position was recorded using an optical-based inertial tracker attached to the night vision goggle mount of the subjects' flight helmets. Matched-pair t-tests were implemented to compare the maximum CROM between aircraft and simulated flights and the published general population. Results: The percent of flight time in severe flexion and lateral bending was not statistically different (P>0.05) between real and simulated flights but was statistically lower in the simulator for severe twist rotation (P<0.05). The maximum CROM for the advanced maneuvers was significantly lower than the norms for the general population (P<0.05). Conclusions: The flight simulator could be a useful platform for flight surgeons determining CROM-related flight fitness if methods to increase the frequency of neck twist rotation movements during flight were implemented. The published maximum CROM values for the general population are not an appropriate reference for flight surgeons making flight fitness determinations related to CROM.