The robustness of flight behavior in a high-lift configuration will be investigated and characterized with stochastic methods. The initial uncertainties in the aircraft flight mechanics models will be approached with the help of functional approximations which use a low-rank representation and will be modeled, specified by probabilistic methods, and numerically efficiently represented. These stochastic models for the forward simulation allow for an assessment of the robustness of the highlift configuration. They will be updated with Bayesian methods for the improvement and identification of the uncertain quantities in the models with the help of the more precise RANS-calculations.