There is widespread and growing interest in the potential use of distributed simulation for aircrew team and collective mission training for military operations. Live flying training is becoming increasingly limited due to a combination of factors, including lack of airspace availability, environmental and security constraints, concern about consumption of aircraft flying hours and airframe life, the cost of major exercises and limited opportunities to practise co-ordination of critical multi-national NATO air missions in a representative operational environment, complete with threats. Furthermore, peace-time constraints typically preclude full operational use of electronic warfare (EW) systems, deployment of defensive aids such as chaff and flares and firing of live weapons. Data links are also extending the ‘tactical reach’ of an air package. Thus, training methods have to adapt.