Abstract: In order to ensure safety of aircraft wake separation in high-altitude en-route phase, firstly, a safety assessment model of wake vortex was established by a fast simulation method, and induced rolling moment coefficients were selected to reflect severities of wake vortex encounters. Secondly, dissipation of wake vortices and safety of vortex flow fields at high altitudes were analyzed, and acceptable safety levels of wake separation for different aircraft combinations were obtained. Finally, influence of different bank angles and flight speeds on severities of high-altitude wake vortex encounters were calculated. The results show that compared with those in medium- and low-altitudes, wake vortices in high-altitudes have larger initial strengths and dissipation rates, and aircraft can be dangerous after flight altitudes exceed 13 000 m. At some distance behind current wake separation, there are still larger encounter strengths. Safety of vortex encounters can be improved by properly decreasing leading aircraft's bank angle and increasing following one's flying speed.

Key words: high-altitude aircraft wake vortex, safety assessment model, induced rolling moment coefficient, wake separation, hazard area