Why do humans develop systems? The answer is clear: to realize system capabilities by utilizing these systems. Unless a system realizes the intended capability, it is useless, even if the system itself is perfect. Every system needs something to be realized. The problem is that we do not know how to deal with unexpected problems that prevent the realization of the system capability. Of course, many studies have been conducted on how to develop robust, fault tolerant systems, but there is no existing research on how to determine the system’s resilience in relation to its capability. The system capability can be realized by developing a resilient system. In this study, we developed a system ontology especially for a weather observation system. This ontology can describe the entire system by applying DODAF 2.0 and an enabler relationship. It allows us to determine all of the system entities and relationships. In addition, the ontology shows the system’s resilience by considering the realization of the system capability. This ontology was applied to a weather observation system to verify its effectiveness.