An active flow control system for controlling an airflow over a vertical control surface of an aircraft, comprising: the vertical control surface comprising a vertical stabilizer and a rudder that is attached to the vertical stabilizer via a hinge; a plurality of active flow control actuators (AFCA 134) mounted within the vertical control surface according to a plurality of zones (202, 204, 206) and operative to alter a flow characteristic of the airflow over the vertical control surface when activated to prevent flow separation; and an actuator control system communicatively linked to the plurality of active flow control actuators, the actuator control system comprising: an event detection system comprising: a plurality of sensors operative to collect data associated with a flow control event indicative of flow separation, the plurality of sensors include at least two types of sensor from the group comprising pressure sensors, rudder deflection sensors, control input sensors, and flight parameter sensors; and a controller (604, 606) comprising: a detection system controller; and an AFCA controller, wherein, the event detection system is arranged to transmit the sensor data to the detection system controller, which is operative to utilize the data to detect the flow control event indicative of flow separation and forward this determination and all appropriate data, such as the type of event, the location of the event, and the severity of the event, to the AFCA controller which is arranged to identify a subset of the plurality of active flow control actuators corresponding to a zone for controlling the airflow in response to the flow control event indicative of flow separation, and to activate the subset of the plurality of active flow control actuators in the zone to prevent flow separation. the vertical control surface comprising a vertical stabilizer and a rudder that is attached to the vertical stabilizer via a hinge; a plurality of active flow control actuators (AFCA 134) mounted within the vertical control surface according to a plurality of zones (202, 204, 206) and operative to alter a flow characteristic of the airflow over the vertical control surface when activated to prevent flow separation; and an actuator control system communicatively linked to the plurality of active flow control actuators, the actuator control system comprising: an event detection system comprising: a plurality of sensors operative to collect data associated with a flow control event indicative of flow separation, the plurality of sensors include at least two types of sensor from the group comprising pressure sensors, rudder deflection sensors, control input sensors, and flight parameter sensors; and a controller (604, 606) comprising: a detection system controller; and an AFCA controller, an event detection system comprising: a plurality of sensors operative to collect data associated with a flow control event indicative of flow separation, the plurality of sensors include at least two types of sensor from the group comprising pressure sensors, rudder deflection sensors, control input sensors, and flight parameter sensors; and a controller (604, 606) comprising: a detection system controller; and an AFCA controller, a detection system controller; and an AFCA controller,