Flexible maintenance in aircraft rotation models: a modular component of the digital airline twin

The planning processes of an airline are complicated due to the multitude of options. Additionally, it takes a long period of time from the first planning steps, like creating the network and defining the fleet, until the flights are executed. The development of the digital airline twin (DAT) at the German Aerospace Center (DLR) is motivated by the objective of simulating and optimizing these processes. The DAT will be a general tool which can be used for airlines with different business strategies and to answer various research questions. By dividing the processes into smaller sub-processes, each model can calculate larger instances and feedback loops can be included to iterate the results. One of these planning processes is the generation of aircraft rotations, which are sequences of specific flights within a given time frame that are later assigned to individual aircraft, known as aircraft rotation problem. This includes the necessity for sufficient availability for regular maintenance for each rotation in order to ensure operational efficiency and safety. To enable flexible, feedback-driven use within the DAT, different simplifications are implemented that leave space for further, more detailed airline planning steps. This paper presents two approaches. Both including sufficient availability for maintenance in each aircraft rotation for an airline to later schedule specific maintenance events. Moreover, the results regarding a one-week flight schedule are compared and the suitability of the approaches for the DAT is discussed.