The addition of load transducers to measure internal reactions between the lumbar spine and pelvis of the HYBRID III anthropomorphic test device (ATD) represents an important capability to military researchers. This paper examines the results of a test program to assess the lumbar spinal response of the Hybrid III ATD exposed to representative helicopter crash pulses. The following independent variables were studied: manikin size, upper torso restraint, abdomen presence, velocity change, onset rate, and peak sled acceleration. Descriptive statistics and the General Linear Model Analysis were used to analyze the data. Test results support use of lumbar force as a physiological compliance index for military crash resistant seats.