Effects of scheduling and spacing tools on controllers´ performance and perceptions of their workload

A human-in-the-loop simulation of an integrated set of time-based automation tools that provided precision scheduling, sequencing and ground-based merging and spacing functions was run in the fall of 2010. These functions were combined into the Terminal Area Precision Scheduling and Spacing (TAPSS) system. TAPSS consists of a scheduler and two suites of advisory tools, one for the Air Route Traffic Control Center (ARTCC, or Center) and one for Terminal Radar Approach Control (TRACON) operations. Both suites are designed to achieve maximum throughput and controllability of traffic. The subject airspace was the terminal area around Los Angeles airport (LAX) and the en route space immediately beyond. Scenario traffic was based on the demand from today\´s heavy arrival periods, and traffic levels were simulated that matched these or added five, ten or twenty percent to this amount. Eight retired, highly experienced controllers worked two final, three feeder and three en-route positions to deliver traffic to the two outboard arrival runways at LAX (24R and 25L). Although the main research question was whether controllers could safely control the traffic, their level of performance was also of interest and how the advanced tools facilitated or hindered their tasks. The results show that the TAPSS tools enabled higher airport throughput and a larger number of continuous descent operations from cruise to touchdown for the jet aircraft in the scenarios. This contrasts sharply with the "current day" operations in which the Center controllers utilize step-down descents to meter the aircraft. Reported workload levels were lower in the "TAPSS tools" condition than in the "current-day" condition and the TAPSS operations earned cautiously acceptable ratings, indicating the prototype tools have value.