ESDU 90008 discusses the flow phenomena that occur in steady high subsonic flow over aerofoils and wings, and the prediction of the initial stages of shock-induced separation. The development of regions of supersonic flow on an aerofoil is first considered, at constant angle of attack as Mach number increases and at constant Mach number as angle of attack increases. The influence of various features of the flow, illustrated by visualisation photographs, on the aerofoil aerodynamic characteristics is shown graphically. The interaction in attached flow of the shock with a turbulent boundary layer is considered and a correlation shows the effect of the upstream boundary layer conditions on the length of the interaction region. Shock-induced separation is then discussed, also illustrated with graphs of the Mach number contours in the vicinity of the shock and corresponding flow visualisation pictures, and the types of separation met are explained. A broad criterion for separation is suggested and a correlation of separation bubble length in terms of the upstream boundary layer parameters is included. A correlation of conditions for flow breakdown is also given. There is a brief discussion of the occurrence of transonic conditions on high lift devices, where supersonic flow can exist at freestream Mach numbers as low as 0.2. Finally, three-dimensional effects are considered, initially in terms of the infinite yawed wing, and then in terms of the tip effects introduced with finite aspect ratio.