UNICOS is a CERN framework to produce control applications. It provides operators with ways to interact with all process items from the most simple (e.g. I/O channels) to the most abstract objects (e.g. a part of the plant). This possibility of fine grain operation is particularly useful to recover from abnormal situations if operators have the required knowledge. The Virtual UNICOS Process Expert project aims at providing operators with means to handle difficult operation cases for which the intervention of process experts is usually requested. The main idea of project is to use the openness of the UNICOS-based applications to integrate tools (e.g. Artificial Intelligence tools) which will act as process experts to analyze complex situations, to propose and to execute smooth recovery procedures. . The paper first introduces the architecture of the UNICOS based applications and the problems operators are faced to. It describes then the tools offered to the operators and the global architecture of the solution. It details after the knowledge base, the rule based engine and its integration in the UNICOS architecture. Finally hints about future evolution of the project will be given.