Development of a Wake Vortex Spacing System for Airport Capacity Enhancement and Delay Reduction

A number of factors lead to a reduction in airport capacity in weather conditions that prevent the use of visual approach procedures. These factors include a reduction in the number of available runways and the longitudinal wake turbulence separation constraints used by Air Traffic Control (ATC). These wake constraints (table 1) evolved over time to prevent wake encounters in weather conditions most conducive to long-lived wakes, and are unnecessarily large in weather domains that lead to rapid wake decay or drift away from the flight path. During visual conditions aircraft separation responsibility belongs to the pilots, who use their knowledge of weather conditions, lead aircraft type, and lead aircraft flight path to effectively self-separate from wake encounters. In many situations the resulting spacing is less than would be required in instrument operations [1]. The AVOSS is designed to structure this process and minimize the difference in aircraft spacing between visual and instrument operations. The operational concept of AVOSS is to determine the spacing required to prevent wake vortex encounters, given the ambient weather conditions in existence at the airport. The basic AVOSS architecture is unchanged from previous descriptions [2, 3, 4, 5, 6] and shown in figure 1. The AVOSS system uses sensed weather information to predict wake vortex behavior and develop safe spacing criteria. The meteorological subsystem uses sensors and modeling techniques to describe the vertical profiles of the wind, turbulence, and temperature from the surface to the glide slope intercept altitude. A statistical description of relevant variables is provided to minimize spatial effects and permit prediction of the worst-case wake behavior that may occur during an operational time period. The wake predictor