This paper presents preliminary results from an ongoing research effort towards the development of a multi-event trajectory optimization methodology that allows to synthesize RNAV approach routes that minimize a cumulative measure of noise, taking into account the total noise effect aggregated for all inbound flight movements taking place within an operational year. This new development is an extension of a tool called NOISHHH which was developed earlier for the synthesis of single-event noise abatement RNAV trajectories into and out of airports. Although the presented numerical examples pertain to a specific airport in the Netherlands, viz. Rotterdam the Hague airport, this study focuses on the development of a generic methodology that can be applied to any given airport. Initial application of the adapted optimization framework to the design of noise abatement RNAV approach routes at Rotterdam The Hague airport reveals a significant potential for reducing the number of people highly annoyed due to annual noise exposure relative to the existing situation.