Impact of Conflict Avoidance Responsibility Allocation on Pilot Workload in a Distributed Air Traffic Management System

Pilot workload was examined during simulated flights requiring flight deck-based merging and spacing while avoiding weather. Pilots used flight deck tools to avoid convective weather and space behind a lead aircraft during an arrival into Louisville International airport. The study examined concepts placing conflict avoidance responsibility on different combinations of pilot, controller and automation. An ATWIT metric, modified to measure workload, showed highest workload during the approach, and lowest during the en-route phases of flight (before deviating for weather). The trend across multiple workload metrics showed workload to be lowest when pilots had both conflict alerting and responsibility for avoiding conflicts; while all objective and subjective measures showed workload was highest when pilots had no conflict alerting or responsibility for avoiding conflicts. The findings suggest workload is lowest when pilots have conflict alerting displays plus responsibility for conflict resolution; and highest when they had neither the displays nor responsibility. This suggests workload is primarily driven by an attempt to regain situation awareness when conflict alerting is unavailable. It also suggests that workload is not tied primarily to responsibility for resolving conflicts, but to maintaining situation awareness. In general, the modified ATWIT was shown to be a valid and reliable workload measure, providing more detailed information than post-run subjective workload metrics.