over the next several decades exacerbates these pressures. Of course, as with safety, so with efficiency: advanced air traffic control automation is not the only solution. In particular, the concept of free flight (RTCA,1 1995a, 1995b; Planzer and Jenny, 1995) is a solution that allocates greater responsibility for flight path choice and traffic separation to pilots (i.e., between human elements), rather than necessarily allocating more responsibility to automation. Automation is viewed as a viable alternative solution to solve the demands for increased efficiency. Furthermore, it should be noted that free flight does depend to some extent on advanced automation and also that, from the controller's point of view, the perceived loss of authority whether it is lost to pilots (via free flight) or to automation, may have equivalent human factors implications for design of the controller's workstation.
It is, of course, the case that automation is made possible by the existence of technology. It is also true that, in some domains, automation is driven by the availability of technology; the thinking is, "the automated tools are developed, so they should be used." Developments in sensor technology and artificial intelligence have enabled computers to become better sensors and pattern recognizers, as well as better decision makers, optimizers, and problem solvers. The extent to which computer skills reach or exceed human capabilities in these endeavors is subject to debate and is certainly quite dependent on context. However, we reject the position that the availability of computer technology should be a reason for automation in and of itself. It should be considered only if such technology has the capability of supporting legitimate system or human operator needs.
Automation has the capability both to compensate for human vulnerabilities and to better support and exploit human strengths. In the Phase I report, we noted controller vulnerabilities (typical of the vulnerabilities of skilled operators in other systems) in the following areas:
Monitoring for and detection of unexpected low-frequency events,
Expectancy-driven perceptual processing,
Extrapolation of complex four-dimensional trajectories, and
Use of working memory to either carry out complex cognitive problem solving or to temporarily retain information.
In contrast to these vulnerabilities, when controllers are provided with accurate and enduring (i.e., visual rather than auditory) information, they can be very effective at solving problems, and if such problem solving demands creativity or access to knowledge from more distantly related domains, their problem solving