The increased tasking and reduced manning of a multi mission aircraft put pressures on the mission-crew in terms of their workload, mixture of skill and the training required. This paper describes the simulation undertake by CORDA for the UK Air Warfare Centre. Within the model, written in EXTEND TM (Imagine That Inc.), the mission is defined in a modular form, which allows the mission tasks to be developed and modified as the study progressed. Workloads are associated with each task which are then distributed amongst the mission-crew. Within the model supervisory roles, relief crew and rest periods are modelled. The design has provided a generic simulation approach to mission-crew loading which allows the analyst to study variations and sensitivities in a controlled manner. This allows the optimum capability to be assessed and the minimum training / manning burden to be associated with the introduction of new aircraft technologies and skills.