Incorporating human factors concerns into the design and safety engineering of complex control systems

A major concern for those designing safety-critical, high-reliability, or dependable control systems is ensuring that they meet the same rigorous safety standards as the underlying complex systems which they control. As hardware components have become more reliable, and their properties better understood, it has become easier to make safety claims about these aspects of a system. Even for software components, which have benefited from structured and formal methods to specify their intended behaviour and rigorous verification and validation techniques to test this, safety claims are now possible. Usability issues, particularly operator errors, are an Achilles Heel for safety engineering. Systematic approaches to the inclusion of human factors concerns in rigorous safety engineering practice are long overdue. In this paper we draw on our recent experience of the design phase of a major communications system, and discuss why simply passing new isolated techniques into the safety arena is insufficient. We go on to demonstrate how insights from an established cognitive engineering technique (Programmable User Modelling) could be fully incorporated into existing safety engineering practice.