The Safety Critical Systems Handbook, 4th Edition

A Quick Overview

Functional safety engineering involves identifying specific hazardous failures which lead to serious consequences (e.g., death) and then establishing maximum tolerable frequency targets for each mode of failure. Equipment whose failure contributes to each of these hazards is identified and usually referred to as “safety related.” Examples are industrial process control systems, process shut down systems, rail signaling equipment, automotive controls, medical treatment equipment, etc. In other words, any equipment (with or without software) whose failure can contribute to a hazard is likely to be safety related.

A safety function is thus defined as a function, of a piece of equipment, which maintains it in a safe state, or brings ...