Future fusion devices are complex systems and present-day experimental devices need additional versatility to test as large a parameter set as possible. To that end, more and more advanced control and monitoring strategies and actuators are used, such that although each element is well known, the system’s behaviour exceeds the predictability of its individual components. As a result, being able to run simple yet realistic enough simulations that include the plant systems, the plasma and their interactions became particularly important. Such simulation platforms, usually referred to as flight simulators, are designed to use the experimental discharge program as input, and to output the temporal evolution of both the plant and the plasma quantities. In addition, flight simulators are expected to be used iteratively to test and improve scenarios or models. Therefore, while any integrated model is technically eligible, only simplified models remain practically viable due to the time constraints. The tutorial paper is based on a lecture delivered at the 14th ITER International School focused on ‘Integrated Modelling of Magnetic Fusion Plasmas’. It describes the concept of flight simulators, with a focus on the control system elements surrounding the physics model. In particular, the requirements and benefits of closed-loop simulations are highlighted.