A method of launching a catapult, a catapult and a locking device for a catapult. The catapult comprises a carriage (4) for fastening an aircraft (5). The carriage (4) can be provided with a high acceleration by directing a launching force (F.sub.1) generated by a launching device thereto. The carriage (4) can be held at a launching position (6) by means of the locking device (9). The catapult further comprises a takeoff damper (34) that generates a damping force (F.sub.2) having a direction opposite relative to the launching force. Accordingly, the takeoff damper (34) restricts the acceleration of the carriage (4) at the initial launching moments.