The use of computers in process control has improved productivity and product quality but has also caused a number of accidents. If we learn from these accidents we may be able to prevent them from happening again. This paper advocates a systematic approach to deriving and organising safety-related questions from past incidents and then applying the questions to consider the safety issues related to the whole life-cycle of computer-controlled plants. Over 170 questions were derived from 300 incident reports provided by two major organisations. The questions are organised into a structured framework so that relevant questions can be located easily when considering different aspects of a computer-controlled plant. Examples illustrating the application of the questions are given. The whole set of questions is listed in the Appendix.