“We'll know we have a problem, and we'll fix it!” – Overestimating human response as a safeguard

Abstract Human response to an alarm is a frequently claimed safeguard in many process hazard analysis (PHA) studies. Correct human response to abnormal conditions can be a powerful safeguard in preventing catastrophic process safety events, but human response also has several significant limitations to consider and overcome. It is incredibly tempting, in the relative calm of the PHA discussions, to assign near‐superhero qualities to operations personnel in how they respond to upset conditions and attempt to prevent upsets from escalating to loss of containment events, oftentimes supported by anecdotal stories by personnel. However, the reality of chemical process operations is generally much messier and more complex. Failure to reflect honestly on the physical and mental capabilities and limitations of the humans charged with making critical process decisions will result in a higher‐than‐expected risk of process safety events. This paper will evaluate some of the ways human response can be overestimated as a safeguard and illustrate them with real‐world examples. Facing the limitations of human response in each scenario can help manufacturing leaders and process safety specialists identify ways to strengthen it. Factors to consider when relying on human response and ways to improve the effectiveness of human safeguards through both engineering design and human factors will also be discussed.