Although there are numerous definitions of safety, we adopt the commonly held view that it can be defined as freedom from unacceptable loss (accidents). Losses can include human impact (fatalities and serious injuries), economic impact (financial return or the economy), social and environmental impact (social disruption or environmental damage) and outrage (loss of public confidence and damage to brand).
Reliability in engineering is defined as the probability that the behavior of a given component (technology, person, organization) satisfies its specified requirements over time and under given conditions.
Some approaches treat reliability and safety as equivalent but they are not and, in fact, they often conflict.
Some models advocate structures and practices that aim to make the organization reliable (e.g. consistently deliver gas) but say little about how the organisation should reduce accidents. The plant is reliable but unsafe.
Other models focus on safety and the creation of ‘harm free’ organisations, yet these approaches can lose sight of business objectives. For example, the best way to ensure safety is to reduce production or not operate the system at all. Reducing capacity makes the plant “unreliable” with respect to its mission but it is safe.
The key management challenge is finding an appropriate balance between safety AND reliability. This is an important distinction in relation to any organization. The very best organizations achieve exceptional levels of BOTH safety and reliability.