This paper analyses the system requirements for an assistance agent that is aware of the task context of the user and is thus able to initiate interventions that are aligned with the activity of the pilot. Since this agent is based on cognitive processes involved in human multitasking, a deep understanding of the multitasking context is essential from the designer’s perspective. We have reviewed literature on the factors of human multitasking that are relevant to the supervision of unmanned aerial systems. As a result, we propose the system requirements that emerge from the findings of the analysis. Finally, we show how these requirements have been implemented in activity recognition and mental workload assessment as part of a task-aware agent. Our goal is the development of adaptive assistance systems to support the management of unmanned aerial systems in a military air operation.