Sharpening the focus on safety

The news media frequently report that public safety is threatened by deficiencies in technology. Engineers have difficulty in evaluating such charges, and even in defining safety, which involves subjective factors difficult to quantify. Nevertheless, engineering decisions involving safety must be made. System safety engineering procedures can be of assistance. In transportation control systems, fail-safety is basic to safety assurance. Fail-safety for electronic systems is achieved by methodical analysis and test, and by use of other techniques, including diversity and cycle checking. New technology, such as the microprocessor, introduces new safety requirements to which system safety engineering will also apply.