The integration of aeroengines with open fan architectures remains one of the most challenging tasks in the design of next generation aircraft. Tackling such a design problem can only be achieved by the coherent endeavor of various disciplines. In this regard, CODA (CFD Onera DLR Airbus) is being developed by the German Aerospace Center (DLR), the French Aerospace Lab (ONERA) and Airbus as a next generation CFD solver, with both aircraft and aeroengine fan design capabilities and optimized for modern HPC architectures \cite{Goertz2022}. The accurate simulation of flows across the aeroengine fans requires the correct treatment of the boundary conditions, which are particularly challenging due to physical complications and geometrical constraints originating from the problem’s nature. A pivotal approximation in the coupling of the adjacent blade row domains in relative motion with respect to each other, is the mixing plane boundary condition. Despite the unsteady nature of flows through cascades of rotating and stationary blades, the mixing plane approach – accounting only for the time-mean interactions between the blade rows – has proven beneficial as an efficient method for steady computation of the flows within compressor and turbine stages. One crucial aspect that must be taken into account while formulating the mixing plane boundary condition arises from the fact that the artificial boundary is inevitably located close to the field of interest. Therefore, in order to avoid spurious reflections emerging at the boundary and corrupting the solution, the mixing plane method must be combined with non-reflecting boundary conditions \cite{Giles1991}. In this work, the existing one-dimensional non-reflecting boundary conditions are enhanced through a more advanced, state-of-the-art alternative. In particular, we present the implementation of the new variant of the mixing plane boundary condition in CODA, examine issues impacting stability and efficiency, and discuss the accuracy improvements achieved through its use.