Human Systems Integration Division @ NASA Ames

Controller workload is a key factor in limiting en route capacity that has been modeled through fast-time modeling, real-time simulations, and operational data. In most of these efforts, the focus has been on correlating workload with other "objective" metrics, such as number of clearances, number of aircraft, etc. A missing component from such analyses is the controller's strategy for managing workload. Workload is not a passive factor that mirrors the controller actions (e.g. handoffs, clearances). Instead, controllers actively moderate and re-distribute the types and the frequency of actions based on their perceived workload. In this paper, we examine this strategy shift by associating bookkeeping tasks and route/altitude clearances with online workload ratings. Overall, the data suggest that only in high traffic scenarios in which the controller workload approached the maximum threshold,, the controllers shed peripheral tasks related to monitoring and bookkeeping as the traffic increases and their perceived workload transitions from low to high. Whenever workload reached a maximum, some bookkeeping tasks were delayed and performed in "groups" after the peak traffic subsided.