We give an overview of the existing commercial tools for the design of real-time concurrent systems and propose a list of features the ideal design environment should have. Then the COVERS tool is described. Its underlying abstract model is a derivative of the Timed Transition System. The concrete modelling language is based upon the structural, behavioral and data processing views on the real-time concurrent system. COVERS supports a sequential subset of Statecharts and ANSI C. The formal semantics of the concrete model is presented. We describe a method of testing the real time temporal properties using spy processes, and, briefly, debugging and performance analysis means.