The human simulation: resolving manning issues onboard DD21

The limitations that human operators impose on task execution are rarely integrated into simulations of complex systems, resulting in considerable loss of outcome fidelity. A discrete-event simulation tool, Micro Saint, was used to stochastically model the impact of human interactions in a comprehensive model of the next generation US Navy destroyer, DD21, to support the Blue contract competitor team. Mission essential tasks performed by a 3-operator and a 4-operator configurations were modeled during a demanding 2.5 hour land attack scenario. Estimates of utilization rate for the two configurations revealed that two of the operators were tasked more frequently during the 3-operator configuration compared to a 4-operator configuration. Workload estimates showed that Operator 2 was working with significantly increased workload for the smaller watchteam configuration. The workload for Operator 2 dropped 36% when Operator 4 was added to the mission. This over tasking likely contributed to the finding that the smaller configuration could not respond to a call for fire in support of ground forces before 179 seconds whereas the 4 operator team responded within 61 seconds. The DD21 model suggests that the small watchteam configuration might not be acceptable, particularly during missions lasting over several days