Product lines (groups of highly similar products) have recently received a great deal of attention in the software engineering community, and especially in organisations that develop products that contain embedded software. The product-line concept provides a constrained production environment that facilitates change and reuse between members of the product line. The reported successes of the last few years concentrate on the embedded software product, but do little to address the wider issues of integrated systems engineering, and certainly do not address the safety process. We believe that there is an enormous benefit to be gained by applying the successful disciplines of software product-line engineering to the system safety process. The results thus far indicate that these techniques can help in enhancing the completeness and robustness of a product line's safety-related requirements. This paper focuses on the phases of the system safety process that affect system requirements.