The aim of this paper is to introduce a case study aiming at better taking into account the impact of changes on industrial safety. It has been well documented in the past years that many accidents did happen because of changes, combining together technological and social dimensions, making of this issue a complex one. This case study had as a purpose to reduce the complexity of the problem by choosing a technologically and organisationally rather limited system, exploiting hazardous processes, where implications of changes could be identified and discussed with a limited number of persons. Silos, with risk of fires and explosions, are main installations of the seed industry and exploited by a limited number of persons within often medium size organisations. This was therefore a rather good case to start with. After that a company agreed to take part of the research, interviews with individuals and visit of a site was organised. Changes were identified and analysed in relation to industrial safety. Regulatory, organisational and technological changes were retained as significant. The interesting turn of this study occurred when a serious accident happened a few days before the feedback session on the outcomes of the study. The company asked then an investigation to be performed and this provided a very good opportunity to go further in the appreciation of the impact of changes in the light of the accident. The investigation showed that many of the changes identified in the first part of the study did play a strong part in the genesis of the accident, although they were not formulated with the level of details one is able to produce retrospectively with an investigation. This case study brings therefore very interesting empirical data to the question of whether or not one is able to anticipate incidents or accidents given specific technological and organisational configurations and evolutions. This approach of combining both perspectives (a study of changes in normal operation and an accident investigation for the same case) also brings diachronic considerations to the mainly synchronic approach explored so far in studies of normal operations.