The display of uncertainty information on the working position

In air traffic control - and in many other domains - decisions are frequently based on uncertain information, most obviously where they involve predictions of future system states. Eliminating the uncertainty completely will not be possible and may in some cases not be desirable, for example where it restricts the flexibility of the human operator to an unacceptable degree. One might ask whether there are situations in which quantifying and presenting information about the inherent uncertainty might provide additional safety and operational benefits and that, in fact, is the question the research presented here attempted to address. As part of a study under EUROCONTROL´s innovative research programme (Van Gool, 2001), existing implementations of two elements of the likely future controller working position (CWP) were complemented with a depiction of uncertainty. The elements were the vertical assistance window (VAW), a tool that displays aircraft vertical flight paths, and the medium term conflict detection (MTCD) system. The displays showed ´uncertainty bubbles´ in order to represent the predictions´ range as well as their mean. Experiments were conducted in order to investigate the usability of the tools and the impact it may have on controller workload. The paper discusses the implementation of the uncertainty display and explains why certain choices were made. It presents the results of the experiment and points towards other potential implementations where uncertainty displays might offer benefits.