Quick recovery or recovery support of a faulty power generating facility by real time diagnoses such as facility failure diagnosis, supervision for failure symptoms, facility diagnosis by evaluation of performance using databases between the power generating facilities and an operation control system. The operation control system transfers information on operating status and secular characteristic changes of apparatus from power generating facilities or information from operators of selected power generating facilities. The level of a failure of a power generating facility which has a failure is evaluated and repairing information (e.g. recovery procedures, processes, required parts, inventory of the parts, possible failure causes, etc.) is automatically created from repairing information prepared in advance for each evaluation condition. The repairing information is then sent to the operation supporting section of the power generating facility.