AN INDEX OF DYNAMIC DENSITY

The risk of a collision between aircraft is rising as the density of c ommercial air traffic increases. This trend, together with the overwhe lming need to upgrade the National Airspace System, has motivated the Federal Aviation Administration to sponsor the development of metrics to evaluate ''dynamic density'' - a proxy for the likelihood of collis ion risk. Here we propose and evaluate a mathematical index of dynamic density, D, that describes collision risk. Although our domain of inv estigation is aviation, the logic of D is applicable whenever objects move in limited spaces. A series of sensitivity analyses illustrate ho w D responds to frequently encountered air traffic conflict situations . We illustrate a use of D that characterizes pilot performance and ef ficiency in experimental simulations of free flight and suggest other human factors applications. This research could be applied immediately by the traffic management units of en-route air traffic control cente rs to reformulate the criterion for the critical capacity of sectors.