Flight control systems for advanced VSTOL aircraft present unique challenges and opportunities. The designer must address a broad range of questions on control laws, displays and inceptors (cockpit controls).VAAC is a programme of research into advanced VSTOL flight control. Its objective is to develop concepts, and design and assessment techniques. It takes studies through piloted ground-based simulation to flight in the RAE VAAC research Harrier. The experimental flight control system fitted to the VAAC aircraft has been designed to permit a wide range of experimental laws to be flown safely.