An aircraft wing having an upper surface, a lower surface, a leading edge and a trailing edge, the wing incorporating an active flow control device comprising: a fluid chamber housed in the wing providing a conduit for receiving fluid and accommodating the fluid at elevated pressure; a first fluid channel having an inlet in fluid communication with the fluid chamber and an outlet on the upper surface of the wing, so that during flight fluid at elevated pressure can be supplied to the fluid chamber and released through the fluid channel, so as to reduce lift; characterized in that the active flow control device further comprises: a second fluid channel having an inlet in fluid communication with the fluid chamber and an outlet on the upper surface of the wing structure arranged aft of the outlet of the first fluid channel; and a valve assembly switchable between a first state in which fluid communication between the fluid chamber and the first fluid channel is enabled and fluid communication between the fluid chamber and the second fluid channel is blocked and a second state in which fluid communication between the fluid chamber and the second fluid channel is enabled and fluid communication between the fluid chamber and the first fluid channel is blocked, so that during flight fluid at elevated pressure can be selectively released through either the first fluid channel or the second fluid channel. a fluid chamber housed in the wing providing a conduit for receiving fluid and accommodating the fluid at elevated pressure; a first fluid channel having an inlet in fluid communication with the fluid chamber and an outlet on the upper surface of the wing, so that during flight fluid at elevated pressure can be supplied to the fluid chamber and released through the fluid channel, so as to reduce lift; characterized in that the active flow control device further comprises: a second fluid channel having an inlet in fluid communication with the fluid chamber and an outlet on the upper surface of the wing structure arranged aft of the outlet of the first fluid channel; and a valve assembly switchable between a first state in which fluid communication between the fluid chamber and the first fluid channel is enabled and fluid communication between the fluid chamber and the second fluid channel is blocked and a second state in which fluid communication between the fluid chamber and the second fluid channel is enabled and fluid communication between the fluid chamber and the first fluid channel is blocked, so that during flight fluid at elevated pressure can be selectively released through either the first fluid channel or the second fluid channel. a second fluid channel having an inlet in fluid communication with the fluid chamber and an outlet on the upper surface of the wing structure arranged aft of the outlet of the first fluid channel; and a valve assembly switchable between a first state in which fluid communication between the fluid chamber and the first fluid channel is enabled and fluid communication between the fluid chamber and the second fluid channel is blocked and a second state in which fluid communication between the fluid chamber and the second fluid channel is enabled and fluid communication between the fluid chamber and the first fluid channel is blocked, so that during flight fluid at elevated pressure can be selectively released through either the first fluid channel or the second fluid channel.