The importance of situation awareness systems in crisis-management scenarios cannot be emphasised enough. These systems enable entire disaster situations to be mapped out in a real-time fashion thereby aiding significantly in human decision-making and the necessary positioning, management and deployment of resources. As a result of the core role these systems play in responding to crises, it is vital that they are highly usable and optimized for human cognition and experience. In this paper we consider this reality in the context of an initial evaluation of the visualisation interface of a situation-awareness tool called Secure Situation Awareness (SSA). Our evaluation seeks to gather useful feedback from potential end-users on the usability of the tool's interface to feed into the design and development of interfaces for similar systems.