Multi-role fighter aircraft are facilitated by operational and platform capabilities that are in turn supported by basic aircraft function. Thermal management (TM) is a basic aircraft function. Effective TM design at the aircraft concept stage can determine if it can support the intended operational and aircraft capabilities early in the aircraft project. In this study, a three-session workshop with a cross-functional team for TM design was conducted at Saab AB. The outcomes from the workshop resulted in a framework for a detailed understanding of the steps to be carried out iteratively for TM design by a cross-functional team. It also provides the dependencies for these steps and the various functional groups that need to be involved in each step. The steps can be used to iterate TM design at the aircraft concept stage and understand the implications on aircraft and operational capabilities. Further, the workshop methodology presented can be used to obtain similar frameworks for design of other basic functions at the aircraft concept stage.