This paper describes the design of a controller for a vertical/shart take-off and landing (V/STOL) aircraft using the Robust Inverse Dynamic Estimation (RIDE) control theory to improve aircraft performance and reduce pilot workload throughout the transition phase from jet to wing-borne flight and vice versa. The controller is required to be effective throughout the speed envelope from hover to 200 knots, during which the aircrafi undergoes significant changes in its dynamics characteristics. The design of the controller is based on a mathematical model of the aircraft linearised at 120 knots, is developed using realistic actuator and sensor models and is extended across the speed range, resulting in the transition envelope controller which is capable of providing acceptable pilot workloads and handling qualities throughout the transition phase. Controller design issues such as the choice of feedback variables, the selection of pilot inceptor configurations and functionalities, and the use of integrator anti-windup techniques in the presence of actuator saturation are discussed. Pilot-in-the-loop simulation studies show that the controller provides good control and handling qualities throughout the transition phase.