The effectiveness, efficiency and satisfaction are key indicators of the Usability of a system. The outcome of the knowledge management process associated with the development of intelligent systems is determinant in this regard. The paper describes the use of the Delphi method to identify the level of fitness that subject matter experts (SMEs) recognize on different types of response units to perform specific disaster response tasks, with the purpose of expliciting the knowledge required for the inference process of the THEMIS intelligent system. Since the SMEs involved in this elicitation process had different levels of experience on different domains of disaster management, to help reaching consensus the Delphi method was modified to weight the level of experience expressed by the SMEs. This variant of the Delphi method is presented, discussing the approach adopted in each step of the iterative process, the obtained results, and the followed validation process.