Defining Accidents and Unacceptable Losses

The first step in any safety effort involves agreeing on the types of accidents or 

Definitions of basic terms differ greatly among industries and engineering disciplines. A set of basic definitions is used in this book (see appendix A) that reflect common usage in System Safety. An accident is defined as  

Accident An undesired or unplanned event that results in a loss, including loss of human life or human injury, property damage, environmental pollution, mission loss, etc. 

An accident need not involve loss of life, but it does result in some loss that is unacceptable to the stakeholders. System Safety has always considered non-human losses, but for some reason, many other approaches to safety engineering have limited the definition of a loss to human death or injury. As an example of an inclusive definition, a spacecraft accident might include loss of the astronauts (if the spacecraft is manned), death or injury to support personnel or the public, nonaccomplishment of the mission, major equipment damage (such as damage to launch 

Humans or human assets on earth are killed or damaged. 

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