MITRE Corporation's Center for Advanced Aviation Systems Development (CAASD), a federally funded research and development center, developed a task-based model for analysing the traffic capacity of en route sectors. The CAASD model used historical flight operations and planning data to simulate the traffic levels and patterns of activity experienced in individual sectors. Sectors experiencing more complex traffic patterns, which require more time-intensive controller tasks per flight, were assumed to reach their maximum traffic capacity with fewer total flights than those sectors experiencing more straightforward traffic patterns. In this way, the model could estimate the real, controller-constrained traffic capacity of each en route sector at different points in time. The Federal Aviation Administration (FAA) asked CAASD to investigate whether its capacity-oriented task load model could also be used to estimate the number of controllers that were needed in position to work each sector’s experienced traffic activity. By generating such retrospective estimates of “positions to traffic” (PTT), FAA believed the model could help inform staffing plans for each en route center. How the model was adapted to meeting these needs is explained and reviewed in this report. This report is organized as follows: Chapter 1 gives the study charge to the Committee for a Review of the Enroute Air Traffic Control Complexity and Workload Model and provides background information. Chapter 2 provides an overview of the modelling effort, including the main assumptions and basic structure of the CAASD task load model and the methods used to convert its output into estimates of PTT. Chapter 3 describes in more detail the individual elements of the model, including the modelled tasks, events that trigger them, and methods used to derive task execution times. It concludes with the committee’s assessment of these model elements and efforts to check their accuracy and that of the modelled task load. Chapter 4 provides a detailed description of the methods used to convert task load estimates into PTT. It concludes with the committee’s assessment of these conversion methods and checks on their validity. On the basis of these assessments, Chapter 5 summarizes the main study findings and conclusions relevant to the statement of task. It concludes with the committee’s recommendations for improving the modelling effort. (Author/publisher) This report is available online at http://onlinepubs.trb.org/onlinepubs/sr/sr301.pdf
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