A high-lift system on the wing of an aircraft and a method for its operation are described. High-lift flaps (2) which are arranged on the wing (1) are extended from a retracted position in order to increase the lift, and a slot (3) through which flow passes from the lower face to the upper face of the wing (1) is opened (advanced slat/flap-gap control). According to the invention, the slot (3) through which flow passes is opened independently of the position of the high-lift flap (2). This makes it possible to selectively achieve a better maximum coefficient of lift (CL) or a better lift-to-drag ratio with less noise being produced.