An Integrated Air Traffic Control Display Concept for Conveying Temporal and Probabilistic Conflict Information

The central role of air traffic control encompasses: 1) minimizing the probability of loss-of-separation conflicts between aircraft, and 2) facilitating the flow of air traffic by providing such services as traffic and weather information and navigational assistance to pilots. In spite of an increasing number of near misses, there have been almost no midair collisions in the past 35 years between aircraft under radar control (McFarland, 1999). Nevertheless, if the current air control system is not redesigned to accommodate increasing traffic, it is anticipated that by the year 2015 a major aviation incident could occur as frequently as every 7-10 days (Perry, 1997). Some of the factors underlying this forecast include inadequacy of hardware due to the fact that many control towers still use equipment that was installed in the early 1970s, as well as recognised deficiencies in current aviation rules. In response to the forecast of increasing air traffic, the concept of free flight, involving the relaxation of many of today’s flight constraints, has been introduced. The economic benefit of increased traffic flow expected from free flight may come at the expense of more potential conflicts, however. In particular, it remains to be shown that this concept will not hinder controllers’ ability to manage air traffic at anticipated increased loads (Wickens, 1998). For example, an analysis of a one day sample of current Eurocontrol traffic, comprising 1000 intersections, showed that with free flight this number would likely increase to at least 62,000 intersections (Ratcliffe, 2001). Exacerbating the challenge of detecting and resolving conflicts is the fact that positions, velocities, and headings of airplanes may vary randomly. In the aviation community some have even argued that the role of controllers and pilots is one of reducing uncertainty (Leroux, 1998). In response to this situation, we present in this paper our design of an innovative air traffic control display concept, incorporating information about not only predicted times to potential conflicts, but also explicit information about the uncertainty of those predictions. It is our aim that this display be useful for facilitating both detection of potential conflicts and planning for conflict resolution. Although earlier research has revealed consistent human biases during probability estimation tasks (Wright, 1982), few studies have been based on human capabilities in dealing explicitly with computation of probability of conflict between airplanes (Yang & Kuchar, 1997; Paielli & Erzberger, 1997). In light of this, our proposed display makes the predicted consequences of uncertainties in velocity, heading, and position of each airplane in a given air space as apparent to the user as possible. Furthermore, the display is also unique in the sense that it conveys the probabilistic, temporal, and spatial aspects of potential conflicts within a single integrated visual pattern.