 Vortilons consist of one or more flat plates attached to the underside of the wing near its leading edge, aligned with the flight direction.When the speed is reduced and the aircraft approaches stall, the local flow at the leading edge is diverted outwards; this spanwise component of velocity around the vortilon creates a vortex streamed around the top surface, which energises the boundary layer.A more turbulent boundary layer, in turn, delays the local flow separation.