The employment of unmanned aerial vehicles (UAVs) in combat operations has demonstrated that UAVs can effectively provide surveillance, reconnaissance, and target acquisition support in place of manned aircraft. However, the Pioneer UAV, currently employed by the U.S. Navy and Marine Corps, has an unacceptable mishap rate. Half of the UAV mishaps are attributable in part to human factors causes. This points to a requirement for developing tailored intervention strategies. This study develops a stochastic simulation model of UAV mishaps to be used for the evaluation of human factor initiatives in terms of budgetary cost and mission readiness. It determines that electro- mechanically caused mishaps cost approximately the same as human factors mishaps. However, in comparison, human factors mishaps degrade mission readiness significantly. Intervention strategies need to address unsafe acts by the operator, unsafe conditions for flight operations, and unsafe supervision. The study recommends the following intervention measures: the use of system simulators; the implementation of improved aircrew coordination training; and the stabilization of personnel assignments.