Situation Awareness (SA) during tele-operation in robot-assisted disaster management has a major impact on the effectiveness and efficiency. Data perceived by the human and robot agents should be processed and shared in such a way that these agents can understand and direct the other agent's behaviors. E.g., for safe and effective tele-operation, the human (team leader and/or operator) and robot need to be aware of (1) the state, location, position and movement of the robot platform and its arms, and (2) the state of robot's environment (such as obstacles, ...). This paper presents an SA-ontology that formalizes the effects of SA-components on the shared control performance. It is based on literature research, interviews with subject matter experts and a field test during a disaster management exercise. The SA-ontology captured all information needs for the teleoperation, and provided further requirements for SA-support functions.