Navy and Marine Corps helicopter mishaps which had a pilot causal factor assigned were examined to determine if the relative military rank of the pilot and copilot was associated with the rate of occurrence per 100,000 flight hours. All class A and B helicopter flight mishaps for the 11 calendar year period 1980-1990 were examined. Although no statistically significant differences were noted, pairing pilots who were of equal rank yielded the lowest rate, seemingly refuting Elwyn Edward's notion that a flat "trans-cockpit authority gradient" may lead to greater problems in the cockpit than his hypothetical "optimum gradient." Moreover, when copilots flew with pilots who differed by two or more ranks, the largest pilot error rate was revealed. This last finding seems to support Edward's hypothesis that a steep "trans-cockpit authority gradient" may be detrimental to aviation safety.