This paper deals with the development of an active fault tolerant control design applied to an aerospace launcher. The method consists of defining and carrying out effective procedures for early detection of some critical situations and providing adequate responses for the safety of the launcher. Actuator fault reconstruction technique is applied to correct corrupted states of the system by reconfiguring the controller. The stability of the controlled system is analyzed using Lyapunov theory. Then, the obtained stability conditions are expressed in LMI terms. The proposed fault tolerant controller consists on an observer-based fault and state estimation which provides an estimation of unmeasured states and faults and plays the role of fault detection and isolation module. The obtained estimations from the observer are then used in the control law in order to preserve some desired performances and stability of the launcher. The effectiveness of the proposed strategy is illustrated from different simulations.