A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle (HLLV). By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second-order systems, i.e., pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer (DAO) was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral-differential (PID) controllers with disturbance compensation were designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be ultimately uniformly bounded by utilization of Lyapunov’s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performance in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults. A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle (HLLV). By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second- Based systems, ie, pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer (DAO) was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral-differential (PID) controllers with designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be substantially uniformly bounded by utilization of Lyapunov’s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performanc e in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults.