Abstract: The receiver aircraft has a lateral dynamic divergent oscillation mode,when flying in the tanker aircraft’s vortex field. In this paper, the pilot transfer function has been used to calculate the stability of the pilot aircraft closed loop system. The result shows that the unstable mode could not be changed into a stable one by using the bank angle feedback control. The unstable mode will become stable if the pilot takes the sideways displacement as the feedback parameter with a moderate gain coefficient in the pilot transfer function. It appears that the pilot must control the aircraft precisely for obtaining the closed loop stability of the receiver aircraft.