The present work is conducted in the framework of the ESA TRP “Launcher Base Flows and Shock Interactions Regions Improved Load Characterization”, where high speed PIV measurements and unsteady pressure measurements performed in the DNW-HST on a 1:60 scale Ariane 5 are compared to simulations using IDDES and ZDES for the same configuration and flow conditions. The goal of the investigation is to identify how well the computations are capable of predicting the salient features of the transonic buffeting phenomenon. In order to make a valid comparison, it is confirmed that both the experimental as well as the numerical data is properly converged in order to extract flow statistics. It is found that due to the spatial filtering inherent to the PIV processing the measured velocity fluctuations are modulated. Furthermore a POD analysis shows that both the numerics and the experiments return the same modes (both for velocity field and pressure distribution) which indicates that both approaches contain similar large scale flow dynamics.