This contribution presents our collider availability model used in FCC study. The model represents failure logics, operations and calculates the integrated luminosity productions, which is one of the key performance indicator for colliders. The operation phases are essential part of the collider model, as several steps are required to prepare the collider for collisions. This means that the luminosity production is not linearly dependent on availability and must be modelled separately. The models allows deriving availability budgets for FCC systems to guide their designs and testing different operation scenarios. We see high potential in applying combined reliability and operation models also in process and manufacturing industry. In this field, often the key performance indicator is the process performance. This can be modelled similarly to the luminosity production in the collider model. Our collaboration between CERN, Tampere University of Technology and Ramentor lead to development of an Open Modelling Approach for Availability and Reliability of Systems (OpenMARS). It answers the modelling needs of today's complex and dynamic systems. The approach is based on ELMAS (Event Logic Modelling and Analysis Software), which Ramentor has used successfully in various industry sectors. For analysis of the OpenMARS models, we developed a calculation engine, which permits efficient parallel simulation in a distributed computing cluster.