The Complexity Construct in Air Traffic Control: A Review and Synthesis of the Literature.

Air traffic control (ATC) operations are the primary activity of the National Airspace System. This report summarizes the literature on ATC operations which has identified factors related to ATC complexity. ATC complexity has two components: sector complexity and traffic complexity. A model is proposed to explain the relationship between ATC complexity factors and controller workload. This review summarizes ATC complexity factors identified in the literature and methods used to measure them. In addition, the literature on information display, controller cognitive strategies, and individual differences is addressed with respect to ATC complexity. Metrics used to assess complexity are described. Airspace factors that correlate with controller performance and workload are presented. Controller information processing strategies that change in response to workload are reviewed. It is concluded that further research should emphasize how to apply these factors to improve sector design techniques and manage controller workload.