This paper proposes a new tool for accident analysis using concepts and approaches from (a) Activity Analysis; (b) Resilience Engineering; and (c) Safety Culture. We outline its development and conduct an application in the subsea operations within the Brazilian offshore oil & gas (O&G) segment. Development was carried out under a participatory research design. The tool consists of a protocol guided by a flowchart and scripts for data collection and analysis. The proposal has helped us to better track contributing factors to accidents within a complex safety-critical domain, as rich findings from ethnographic-oriented activity analysis can be progressively gathered and systematized into a significant database, part of which will be modeled and analyzed through scenarios that explain near misses and accidents from in-depth knowledge of work activity. The tool design allows for identifying instances of manifestation of proactive safety from the work-as-performed, fore fronting the workers’ knowledge, cooperative actions, and decision aides as crucial factors in conducting safe operations and preventing accidents.