aircraft that need control at extreme angles of attack are sometimes fitted with a canard configuration, in which pitching movement is created using a forward foreplane (roughly level with the cockpit). such a system produces an immediate increase in pitch authority, and therefore a better response to pitch controls. this system is common in delta-wing aircraft (deltaplane), which use a stabilator-type canard foreplane. a disadvantage to a canard configuration compared to an aft tail is that the wing cannot use as much extension of flaps to increase wing lift at slow speeds due to stall performance. a combination tri-surface aircraft uses both a canard and an aft tail (in addition to the main wing) to achieve advantages of both configurations.