For fifty years, technological advances, standards, and accident studies helped to raise considerably the level of safety of high-risk industrial organizations. This improvement was obvious enough to consider “ultra- safe systems.” However, recent events such as the sinking of the Deepwater Horizon oil rig , or more recently the explosion of Lac Mégantic demonstrated the limits of the safety of these complex socio-technical systems. Each new major industrial accident challenges the initial safety plan. If today this “big ones” are more rare, their consequences are often catastrophic. These findings on the current limits in the field of industrial safety have to be overtaken. This paper focuse on Safety Management System (SMS). At the interface between intuitive manager, management tool, risk, decision and responsibility, SMS is a central management tool for industrial risks management. More than trigger the decision of anticipation, it must protect the decision-maker and enable the adoption of a posture of prudence, when all weak signals show the resistance of the system. Besides, many documents are now available to design and implement an SMS. Faced with this toolkit, the manager must be supported to select the good model, to allow it to have a critical space in decision ecosystems, that combine ambiguity of the situation, obligation to act, uncertainty about the effects and responsibility for the consequences.