Periodic demands on layers of protection (i.e., prealarms, safety instrumented functions, relief devices, emergency responce systems, etc.) are precursors to more serious incidents. The failure of one or more layers of protection is always part of an accident sequence. When they occur documenting these demands and the associated consequences in a way to facilitate analysis, provides a means to measure process safety management performance. Although process safety metrics are still in their adolescence, this article reviews experiences of development and implementation of a "Challenges to Safety Systems" process safety performance indicator. This article includes a discussion of automating significant portions of the data collection process based on the technical work documented by the CCPS PERD (Process Equipement Reliability Database) initiative. The article also recommends various metrics that can be calculated and describes how the initial foundation developed to support improved process safety can be lever-aged to achieve other benefits, such as design improvements and improvements in the reliability, operation, and maintenance of the facility. (C) 2009 American Institute of Chemical Engineers Process Saf Prog 28: 195-199, 2009