Abstract <p>The problems of the current stage of operation of hazardous industrial facilities and other complex technical systems are considered. A graphical analytical method for optimizing the periodicity (frequency) of control at various levels is proposed. The results of modeling a system safety program for ensuring safe operation of hazardous industrial facilities and other complex technical systems using the mathematical apparatus of semi-Markov processes are presented. An analysis of the results obtained was conducted, and substantiated conclusions were drawn.</p>