The natural unsteadiness of turbomachinery tip leakage vortex has been reported in both measurement and simulation. The visualization and quantification of this vortex wandering are challenging using pathlines or simple vortex identification methods. In the present paper, the tip leakage vortex wandering is investigated in the case of a low-speed fan's unsteady Reynoldsaveraged Navier-Stokes simulation. The wandering motion of the leakage vortex is detected by Banks' vorticity predictor -pressure corrector vortex core line localization method. Despite the low computational costs, the simulation predicted the complex vortical structure present in the blade passage. The vortex detection algorithm proved successful in finding the tip leakage vortex, but it failed to follow the core line upon heavy disturbance in the flow. The extent and the frequency of the vortex wandering were determined.