Systems Engineering

4.5 Safety

Safety is the state of being protected against adverse consequences to living things, or damage and destruction of inanimate objects. It is an inverse measure of other risks than those under the previous heading. So a higher safety level is measured by lower risks. Under the principle of "protecting the innocents", hazards to a crew that volunteers to accept a risk can be higher than those allowed to the public at large. A safe system, such as a nuclear power plant or passenger airplane, may have less than one expected accident during the system life. So safety often involves assessing low probability events. Requirements to maintain control of a system despite failures, inherent fail-safe design, design margins, backup systems, and redundancy can improve safety when properly implemented.