In this paper we focus on the application of integrated formal methods to the specification and validation of a fault tolerant real-time system (the on-board computer of a Brazilian micro-satellite). The work involves the application of a framework which covers from the formal specification to the analysis and use of tools to prove properties of the system. We used Timed-CSP-Z, a combination of Timed CSP and Z, to specify the system behavior, and then a strategy for converting the specification to TER Nets, a high level Petri Nets based formalism with time. The conversion enables us to use the CABERNET tool to analyse the behavior of the system.