Accommodating off Nominal Conditions when Working to a Metered Schedule

Abstract

In a schedule based Air Traffic Management (ATM) system, minor disruptions to the traffic flow could have a wider impact than would be expected as aircraft are linked temporally. However, given the frequency of these minor disruptions, the extent of their impact on operations needs to be scoped. In a human-in-the-loop (HITL) simulation, four TRACON controllers worked arrival traffic to Phoenix airport (PHX), aided by a schedule and controller sequencing and spacing tools. In approximately two-thirds of the runs, either one or two disrupting events that were local or global in nature, were set in motion. Controllers were asked to manage the disruptions and bring the traffic back onto the schedule. The research questions were exploratory: to observe the impact of the disruption, watch how controllers solved these problems and whether the controller tools assisted them. Global events were observed to have a greater impact on TRACON operations than local events as they led to a greater mean path length flown by aircraft through the TRACON and, although reported workload levels remained manageable overall global events created higher reported loads. Controller strategies for resolving events followed a similar pattern: with controllers often solving local problems with speed and moving to using vectors more often during global events. Controllers used their tools in a similar manner to those observed in nominal-operations studies, with the slot marker being the preferred aid regardless of the event. However, due to the range of factors influencing the event, e.g., environmental conditions, aircraft density in the TRACON, etc., sometimes the plan required revision and occasionally events had a wide-reaching effect.