A significant gap exists between accident scenarios as foreseen by company safety management systems and actual scenarios observed in major accidents. Its mere existence, pointing at flawed risk assessments, is leaving hazards unmitigated, threatening worker safety, putting the environment at risk and endangering company continuity. Safety managers and regulators, attempting to reduce and eventually close this gap, not only encounter the pitfalls of poor safety studies, but also the acceptance of unknown risk as a phenomenon, companies being numbed by inadequate process safety indicators, unsettled debates between paradigms on improving process safety, and inflexible recording systems in a dynamic industrial environment. The immediacy of the stagnating long term downward major accident rate trend in the Netherlands underlines the need to address these pitfalls. The main conclusion is that safety management can never be ready with hazard identification and risk assessment.
Keywords: Unknown risk, Seveso Directive, scenario, accident rate