A model framework of air traffic control failure recovery is provided in Figure 1.2. At the left of the figure is presented the vector of possible air traffic control automation functionalities l-i, discussed in Chapters 3-6 of this report. Because automation is not a single entity, its consequences will vary greatly, depending on what is automated (e.g., information acquisition or control action). Next to the right in the figure is a set of variables, assumed to be influenced by the introduction of automation (the list is not exhaustive and does not incorporate organizational issues, like job satisfaction and morale). Associated with each variable is a sign (or set of signs) indicating the extent to which the introduction of automation is likely to increase or decrease the variable in question. These variables are described in the next sections.


One motivation for introducing automation at this time is increasing airspace capacity and traffic flow efficiency. It is therefore likely that any automation tool that is introduced will increase (+) capacity.

Traffic Density

Automation may or may not increase traffic density. For example, automation that can reduce the local bunching of aircraft at certain times and places will serve to increase capacity, leaving overall density unaffected. Therefore, two possible effects (+ and 0) may be associated with density.


Automation will probably increase the complexity of the airspace, to the extent that it induces changes in traffic flow that depart from the standard air routes and provides flight trajectories that are more tailored to the capabilities of individual aircraft and less consistent from day to day.

Situation Awareness and Workload

Automation is often assumed to reduce the human operator's situation awareness (Endsley, 1996a). However, this is not a foregone conclusion because of differences in the nature of automation and its relation to workload. For example, as we propose in the framework presented in Figure 1.2, automation of information integration in the cockpit can provide information in a manner that is more readily interpretable and hence may improve situation awareness and human response to system failures. In the context of information integration in air traffic management, four-dimensional flight path projections may serve this purpose. Correspondingly, automation may sometimes serve to reduce workload to manageable

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