Applying the Model of Expert ATC Decision-Making to Analyze a Loss of Separation Incident

In this paper, we describe a new model of expertise-based decision-making in ATC proposed by Gyles and Bearman (2025) and use this model to analyze a loss of separation incident. The model describes an ongoing iterative process of action-oriented decision-making to ensure that control of the Air Traffic Control (ATC) system is maintained. In the model, ATC decision-making is based on selecting goals, plans, and actions, informed by orientation and situation awareness-building processes, and regulated by a combination of intuitive, automatic responses and deliberate, conscious processes.The model highlighted several issues that enhanced the original analysis of safety factors. These include: 1) the importance of the initial orientation phase to ensure that appropriate goals, plans, and actions are prepared; 2) the need for timely application of conscious, deliberate regulatory processes when relying on automatic intuitive processes; 3) the need to utilize feedforward to anticipate future system states; 4) the requirement to develop implementation intentions to establish sentinel events that can trigger a deliberate conscious review, ensuring that actions and plans still achieve the intended goal; and 5) the need to effectively transition the primary goal from efficiency to safety during loss of separation events. This analysis offers a more nuanced understanding of the reasons behind the controller's actions and provides several new insights into the loss of separation incident. Therefore, the model demonstrates potential as a framework for expertise-based decision-making in ATC and as a tool to enhance the quality of incident investigations, ultimately driving improvements in safety performance. ‘The capacity of the human mind for formulating and solving complex problems is very small compared with the size of the problem whose solution is required for objectively rational behavior in the real world or even for a reasonable approximation to such objective rationality.’ (Simon, 1997, p. 92)