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PT Notes

Black Swan Events and Process Safety

PT Notes is a series of topical technical notes on process safety provided periodically by Primatech for your benefit. Please feel free to provide feedback.

The term “black swan” dates to a time when it was believed that all swans were white and black swans were thought not to exist. The term was used in 16th century London as a statement of impossibility. After black swans were discovered in Australia, the term came to mean a perceived impossibility that might later be disproved. More recently, the term has been defined to mean a rare, unpredictable and catastrophic occurrence.

Unfortunately, if there are process safety incidents that are Black Swan events, they would lie outside the realm of the hazard and risk analysis methods used in process safety to manage process risks and would not be addressed easily by process safety management systems. Also, any suggestion that some process safety incidents are Black Swan events is likely to discourage process hazard analysis (PHA) teams from searching for unusual hazard scenarios and demotivate their efforts to identify hazard scenarios as completely as possible. PHA practitioners must be encouraged to always maintain an open mind when trying to identify hazard scenarios.

Viewing process safety incidents as Black Swan events is inconsistent with the need to create a culture in which process safety practitioners and others maintain a sense of vulnerability towards the possibility of process safety incidents. Encouraging a belief that some catastrophic incidents will occur regardless of what actions may be taken is a sure way to produce a complacent organization that eventually will lead to the occurrence of process safety incidents. Furthermore, a belief that the worst process safety incidents cannot be predicted can lead to a cavalier view of and reduced investments in process safety by making process safety management systems seem futile. History has shown that people readily ignore what are perceived to be long-shot risks in favor of short-term economic gains. Moreover, claiming events as Black Swans in the aftermath of a disaster can be used as an excuse for poor planning and could be used to justify waiting for an event to happen before taking risk management measures.

Fortunately, most process safety incidents are not Black Swan events. Many result from failings in the design and/or implementation of process safety management systems and they could have been prevented using available information and knowledge. A Black Swan event must contain some element of lack of knowledge about the world that permitted its occurrence. It is challenging to identify process safety incidents that meet this requirement. Thus, the view that various notable process safety incidents have been Black Swan events can be refuted. Black Swan events can be eliminated using science to acquire relevant knowledge. Of course, that is what process safety seeks to do.

Fostering the incorrect view that various process safety incidents have been Black Swan events is damaging for the field of process safety. It could have an insidious influence by encouraging a fatalistic view of incident causation and the inevitability of process safety incidents. “Black Swans happen” should not be the explanation provided to the families of people killed in process safety incidents.

An analysis of causes of process safety incidents is provided in the article:

Insights into process safety incidents from an analysis of CSB investigations, Journal of Loss Prevention in the Process Industries, Volume 43, pages 537–548, September, 2016.

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