An extraction impeller (200) for an axial compressor (102) includes first vanes (210) having an elongated S-shape arranged on the surface (204) of an impeller body (202). The first vanes (210) extend radially from an outer flow inlet edge (220) of the body (202) to a flow outlet hub (222) centered on the surface (204) at the rotation axis (A). A radially inner end (224) of each of the first vanes (210) connects at the flow outlet hub (222) in a direction perpendicular to a rotation axis (A). Second vane(s) (230) are arranged between adjacent first vanes (210), and third vanes (240) are arranged between second vanes (230) and between first vanes (210) and second vanes (230). Second vanes (230) are radially longer than third vanes (240). The impeller (200) extracts air from the axial compressor (102) and forms an axial flow with reduced vortex whistle. When used in an axial compressor (102) of a gas turbine system (100), the impeller (200) reduces flow unsteadiness.