Based on a simulation of aircraft operations according to realistic flight schedules, part removals according to their forecasted reliability characteristics as well as delivery and re-balancing logistics, the Inventory Network Simulator (INS) provides the User a forecast of how the inventory network is expected to perform in terms of service level performance and cost. Input from the Field Parameter Analyser is used in conjunction with planned events including flight network, maintenance plans, fleet changes, and modification plans. The Inventory Network Simulator takes into account all types of removals that are expected or likely to take place, including unscheduled and scheduled demand as well as hard-time removals.