VORTEX ADVISORY SYSTEM SAFETY ANALYSIS. VOLUME I. ANALYTICAL MODEL

Abstract : An analysis was conducted to examine the safety of decreasing landing aircraft separations to three nautical miles between the outer marker and the runway threshold. Such reduced separations would only be used when the Vortex Advisory System indicated that wake vortices would not pose a threat to a following aircraft. Based on state-of-the-art models of vortex and aircraft behavior, the analysis indicates that such reduced interarrival separations may be used safely by Large and Heavy aircraft following Heavies. When the analysis is expanded to include an as-yet unproven cross-winds aloft model, the results indicate that reduced separations may be used by all aircraft regardless of leader/follower aircraft type. Volume I addresses the safety problem from an analytic point of view; Volume II (to be published at a later date) will examine the problem using data collected specifically to verify the analytical model; and Volume III (to be published at a later date) will contain a detailed sensitivity analysis of the model predictions and a critique of the assumptions. (Author)