Results from a numerical investigation of the unsteady transonic flow around a supercritical BAC 3-11 airfoil will be presented here. The focus of this paper is the phenomenon of upstream moving pressure waves. The used solver is based on the finite difference discretisation of high order accuracy (
> 5) and explicit time integration. The mechanisms of pressure wave generation, their development and the influences of the inflow parameter like Mach, Reynolds number and angle of attack are investigated in two-dimensional flow simulations. To analyse the three-dimensional effects simulation of the three-dimensional transonic flow is performed for selected inflow conditions and its preliminary results will be presented.