Catastrophic hazard, definition

Each incident is unique. One working definition of Process Safety Incidents is incidents which—in the judgment of responsible, informed, in-plant administrators (such as the shift superintendent or any second-level supervisor)—could reasonably have resulted or actually had resulted in a catastrophic release of highly hazardous chemicals. A catastrophic release for these purposes is a major uncontrolled emission, fire, or explosion, involving one or more highly hazardous chemicals, that presents serious danger to employees in the workplace. 

In the AOP 52 for the calculation of the SSCI it is necessary to know the severity of a hazard. It is categorized in four categories catastrophic, critical, marginal and negligible. These categories are not explicitly defined in the AOP 52 so we guess that these terms can be defined by the user depending on the application, e.g. in the definition of the ALARP approach. This leaves room for interpretations. This holds also true to a lesser extent for the concept of software autonomy of the AOP 52. 

Most industries approach this step in the same way. However, how they differentiate among catastrophic, critical, minor, and negligible hazards may vary. You will need to modify the definitions to fit the particular problem. What is important is that these definitions are determined before work begins. A rule-of-thumb definition for each is the following ... 

In September 1963, the USAF released MIL-S-38130. This specification broadened the scope of the system safety effort to include aeronautical, missile, space, and electronic systems. This increase of applicable systems and the concept s growth to a formal Mil-Spec were important elements in the growth of system safety during this phase of evolution. Additionally, MIL-S-38130 refined the definitions of hazard analysis. These refinements included system safety analyses system integration safety analyses, system failure mode analyses, and operational safety analyses. These analyses resulted in the same classification of hazards, but the procuring activity was given specific direction to address catastrophic and critical hazards. 

A near miss is the occurrence of an unplanned event that did not result in injury, illness, or damage, but had the potential to do so. Only a fortunate break in the chain of events prevented an injury, fatality, or damage. Related terms are incident, close call, near mishap or near collision. The term is often misunderstood and misused. An event is called a near miss to stress that not only did things go wrong,but that a catastrophe was barely missed. In the airline industry, if two airliners pass within a quarter mile of each other, this is by definition a near miss event. Some individuals feel it is a euphemistic term for a near hit. A near miss could be viewed as the partial actualization of a hazard, resulting in an incident rather than a mishap. It could also be a situation where only part of a hazard occurs for various reasons, such as operator alertness and counteraction, thus preventing a mishap event. For example, a collision avoidance system intended to prevent a collision between two aircraft in the same airspace may have failed without any warning, but an alert pilot saw the situation and took countermeasures to prevent a collision. 

Non-conforming safety criteria if there is a common understanding of exactly what the definitions of terms such as improbable, probable, unlikely, minor, major, hazardous, catastrophic, etc., mean, the effort to integrate the safety argument into a system safety assessment will be greatly reduced and auditability will be improved. 

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