In this work-in-progress report we present the results of a preliminary analysis of a set of fieldwork studies conducted in collaboration with a firefighter school and a firefighter brigade. To inspire the design of ubiquitous computing systems, we provide a description of the equipment used by firefighters, practices built upon them and a set of common properties. Keywords Firefighting, Safety-Critical HCI, Ubiquitous Computing, Ethnography ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous.