Citation

Benner L, Sweginnis R. Hazard Prev. 1983; 19(6).

Affiliation

University of Southern California, USA

Copyright

(Copyright © 1983, System Safety Society)

DOI

unavailable

PMID

unavailable

Abstract

The notion of what constitutes a system safety "closed loop" illuminates this problem area. In system theory, a feedback loop is conceived as the information flow from the system output back to the system. This "feedback" is used to change the operation of the system, to correct undesired output.

A completed feedback loop is often termed a �closed loop� by system safety specialists. Two widely held views of what constitutes a "closed loop" can be observed in the system safety field. One is the notion that when a safety recommendation to control a hazard is reported to have been implemented, the recommendation file is closed and the safety loop is closed. A second view is that if the design performs as expected during prototype or preproduction or component tests, this information confirms the analysis and closes the loop for the safety analyst.

Both views reflect inadequate feedback loops. The system safety loop must not be considered closed until the predicted safety risks and safety control system performance levels, as determined by system safety analyses, have been validated or upgraded with ongoing system performance information.