Human Systems Integration Division @ NASA Ames

This paper reports on the performance and workload of pilots participating in a human-in-the-loop simulation of interval management operations during a continuous descent approach (CDA) into Louisville International Airport (SDF). The experiment examined variations in pilot roles and responsibilities in an implementation of interval management automation.

The roles and responsibility manipulation showed that whether pilots were instructed to follow speed guidance strictly, or to exercise their own judgment, had no effect on workload and only a small effect on interval management performance. However, requiring the pilots to
manually enter speeds into the autopilot, rather than having the automation automatically update the autopilot, frequently led to poorer energy management, and higher spacing interval errors at the final approach fix, even in the conditions where pilots were instructed to strictly follow speed guidance. This finding was traced to poorer compliance with the automated speed guidance, lack of awareness of this poor compliance, and insufficient awareness of the energy state of the aircraft. These results suggest that some form of energy guidance may be needed to augment interval management. To do this, recommendations were made for integrating the spacing interval
management automation with near-term or far-term energy management systems. Workload measurement showed that, when pilots were required to maneuver to avoid en route weather, the manual conditions resulted in an increase in workload, although the overall level would still be considered low under normal circumstances.