Commercial airline pilots undergo six monthly simulator assessments throughout the length of their entire career where they are comprehensively examined on both their technical and non-technical performance. This lecture will review the history and development of flight simulators and synthetic training devices from an aeromedical perspective. It will then briefly look at the content of a typical simulator assessment and consider how these training devices can be used at different stages of a pilot’s career. The presentation will explore how these training devices manipulate a variety of human physiological principles and limitations in order to maximize the fidelity of the training experience, with particular reference to the simulator motion and visual systems. Whilst the importance of flight simulators in the aeromedical decision-making process has been long established, the current use of synthetic training devices in aeromedical functional assessments for a variety of conditions will also be considered.