The ailerons droop 5° when the:

The ailerons on the A320 are designed to droop by 5° when the flaps are extended. This mechanism is intended to enhance the aircraft's roll performance during low-speed operations, especially during takeoff and landing phases. When the flaps are deployed, the increase in camber also affects the ailerons. By drooping the ailerons, the aerodynamic characteristics are improved, allowing for smoother roll control and helping to maintain lateral control, which is crucial during takeoff and landing when the aircraft is operating at lower speeds.

This design contributes to effective maneuverability and stability of the aircraft in configurations that require higher lift, ensuring that the pilot can manage the aircraft safely and effectively throughout different phases of flight.