A novel flight control system for a reusable launch vehicle during Terminal Area Energy Management (TAEM), approach and landing phases of flight is presented. In order to provide accurate tracking and bring the vehicle safely to the landing site, the controller must be robust to external unknown disturbances, unmodeled dynamics and plant uncertainties and also be able to perform well under a wide range of operating conditions. This is accomplished using a new approach in Sliding Mode Control which has multiple loop structure with different time scales, and is driven by sliding mode observers combined with gain adaptation. Comparisons with a classically designed controller are made using a well defined, reusable launch vehicle model and considerable improvements in performance are observed. Implications are that this type of design can improve vehicle safety and reliability by improved robustness, and decrease development and operational cost by reducing analysis time.