Filling is a critical stage in resin transfer molding (RTM) manufacturing; it is associated to the formation of impregnation imperfections which can lead to defects. Simulations are typically employed to predict the flow behavior, which however need the preform permeability as an input. Significant work has been done in the past in in-plane permeability identification. This study focuses on the determination of the permeability of unidirectional curvatures typically encountered in RTM parts. A model for analytical calculation and a numerical optimization approach for inverse determination have been developed and applied in an omega-shaped RTM part where material-embedded flow sensors were employed for the essential flow measurements. The differences found between the experimentally derived permeability of the curvature and theoretical predictions were discussed critically and associated to flow time disagreements between simulations and reality.