Improved Understanding of En Route Wake-Vortex Encounters

Wake turbulence can be experienced by aircraft when encountering the wake vortex of another aircraft. The aim of this study is to improve the understanding of the risk posed by en route wake-vortex encounters in the en route flight phase. To quantify this risk, a simulation framework has been conceived that makes use of recorded historical surveillance data and computes the wake-vortex trajectory and decay for each aircraft based on a wake-vortex model. The simulation has been validated and subsequently used to determine the probability of encountering a wake vortex in upper European airspace. The simulation results bear out that a severe wake-vortex encounter can be expected approximately once every 38 days. Three factors have been identified that contribute to the risk of encountering a wake vortex during the en route phase of flight, viz., the characteristics of the exposed or generating aircraft, the encounter geometry, and the prevailing tropopause height in the atmosphere. The combined time evolution of these three factors suggests that the en route wake-vortex encounter risk may increase in the future. Finally, both short-term and long-term mitigation measures are proposed that can potentially reduce the severity of wake-vortex encounters or even prevent their occurrence.