A new generation of night vision goggle (NVG) systems allows pilots to greatly improvesituational awareness and targeting capabilities during nighttime combat missions.However, the integration of such systems results in an increase in head supported weightand a change in inertial properties, which may necessitate the need for an auto-separatemechanism to lower cervical loads and decrease susceptibility to neck injury uponejection. NVG systems were previously tested on a Vertical Deceleration Tower (VDT)using the Hybrid III manikin with successful separation during 11 G impacts. However,as the Hybrid III neck poorly reflects human neck flexion, a validation study usinghuman subjects was conducted for two types of NVG systems, the Panoramic NVG(PNVG) Block 1A and NVCD (Night Vision Cueing Display). Additionally, manikinswith their heads tethered to the headrest to simulate human bracing were tested underidentical conditions. In contrast to the original manikin test results, zero separationsoccurred for the human subject pool or modified manikin tests for either NVG. Althoughthe maximum seat acceleration for the human subjects was only 10 G, some separationwould have been expected since the resultant head accelerations of some of the humanswere similar to those experienced by the original manikins. Both male and femalesubjects tolerated the neck loads well with no medical incidents being reported duringany of the tests, leading to the conclusion that these systems are likely safe to wear duringthe ejection catapult phase. However, modifications to the stiffness of the separationmechanism are recommended in order to ensure full separation prior to the lesscontrollable parachute opening shock phase.
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