This paper describes the objectives and methodology of the APACHE project, a SESAR Exploratory Research project proposing a new framework to assess European air traffic management (ATM) performance. This framework integrates an ATM simulator prototype used to synthesise scenarios for pre-ops performance assessment, but also needed to compute some novel performance indicators, which require from optimisation or simulation capabilities. This simulator embeds a trajectory planner; an airspace planner; a traffic and capacity planner; and finally, a performance analyser module. An illustrative example is given, showing the successful integration of all these modules, where an initial performance assessment is done for a realistic data set of 24h of traffic over the FABEC airspace.