The chapter covers almost two decades of research-the 1970s and 1980sperformed by the Swedish Defence Research Establishment, FOA (nowadays the Swedish Defence Research Agency, FOI), and in close co-operation with the Swedish Air Force1, 2 (SwAF). This work was motivated by an interest in two questions. What are the relationships between experience on an aircraft system, absence from a task/system, speed of skill decay, reacquisition training, and operational performance? What are the transfer effects from simulated to real flight? To answer these questions, a series of studies, simulated and live, were conducted in the Swedish Air Force during the 1970s and 1980s, and the chapter presents a review of these activities. Early retired fighter pilots were compared with active pilots. Performance was the crucial measure. By means of structural equation modeling, valid and reliable performance measures of aircraft, radar, and weapon systems operations were generated and applied, and models of their causal relationships were developed. The pilots’ mental workload, their effort, mood, and motivation were also measured. The more experience with and the less absence from the aircraft the pilots had, the better their operational performance. The non-linear relations found between time on system, absence from system, respectively, and performance, were used for optimal screening of pilots for operational reacquisition training. Once skillful,

the pilots can be away from their systems for quite a while and make a successful comeback, provided that they get individualized and guided training, where the concrete results and performance measures are consistently used in briefings and as information feedback supervised by experienced instructors. The training procedures developed proved effective for keeping the pilots’ motivation at constantly high levels. By means of structural modeling, significant predictions, from simulator to live flight, of the pilot’s capacity and operational performance could be made. Lessons learned from these studies, and connections to training challenges of today conclude the chapter.