process to assess its utility and validity going forward. Specifically, FAA asked the National Academies to convene an expert committee to examine and offer advice where appropriate for improving (a) the overall technical approach of task-based modeling, (b) input data and processes used for modeling traffic activity, (c) tasks and methods used to assign task times, and (d) means for validating model assumptions, parameters, and output. In addressing this charge, the committee was asked to be cognizant of the “overall tradeoffs made due to data availability” and to consider the “adaptability of the approach to reflect changes in the tasks of controllers as their roles evolve over time.” Key study findings with respect to each of these elements of the study charge are given next, followed by recommendations.


Task-Based Approach

The results of task-based modeling can be a valuable source of objective information for workforce planning, and FAA’s current model is a marked improvement over previous models. Earlier models measured the number of aircraft flying through a sector without accounting for the variability in the complexity of this traffic, and thus the variability in controller tasks and time demands. For example, aircraft changing headings and altitude create more traffic complexity than aircraft cruising straight through a sector. FAA’s current model accounts for traffic complexity by simulating the traffic flows and patterns experienced in the en route sectors and relating them to the time-varying tasks that controllers perform. The basic model structure, in which traffic activity is simulated and controller tasks and task times are associated with traffic, represents a logical approach to estimating task load. The methods used to derive model parameters and values and to convert the modeled task load into PTT are the subject of most of the criticism and advice in this report.

Simulations of Traffic Activity

By using available traffic operations and flight-planning data, flight plans, and trajectory modeling, the task load model simulates past sec-

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