A control device for use with an aerodynamic wing including a bar having a safety system that restrains one of the flying lines by routing an attachment through an aperture on the bar. Preferably, the system includes a stopper housing that engages an increased diameter element of the flying line. During normal operation, the increased diameter element is secured by the stopper housing, preventing the flying line from being pulled beyond the stopper housing. When the safety system is deployed, the increased diameter element is pulled from the stopper housing and slack is developed along the remaining flying lines to depower the kite.