Fire departments are one of the most versatile and widespread emergency management organizations. To support their digitalization, innovative firefighter information technologies such as emergency response information systems (ERIS) are suggested. Despite theoretical potentials like raised situation awareness, however, these technologies seem to disseminate only slowly in practice. As existing acceptance models cannot sufficiently explain the acceptance of novel technologies in this special domain, literature calls for increased contextualization. To get insights into the domain-specific acceptance factors, we conducted an ethnography and observed a voluntary fire department's multi-year project to introduce an ERIS. We identified seven factors, like revealing events and error management culture, which acted as triggers for different adoption stages. From overarching characteristics of a voluntary fire department, we derived six additional acceptance factors, like situational adaptability and self-determination. The identified factors can help firefighters in conducting successful digitalization projects, and policy makers in supporting voluntary emergency management organizations. Moreover, the results provide numerous avenues for future research, can be linked to various research fields and contextualize existing acceptance models. Beyond fire departments, the results may be transferred to similar high-reliability organizations.