The article discusses an analysis of the operational and reliability issues, which regards selected fire alarm systems (FAS) exhibiting different functional structures. These systems are operated in a vast transport area, within a specific environment. We can distinguish three basic structures of these systems – focused, dispersed and mixed. A given system functional structure, utilized within a facility (a given area) is a function depending on the configuration, internal connections of elements and devices, and a developed fire scenario. The application of a given system structure for fire protection also depends on the legislation determining the approval of a facility (area) for use. The process of executing a scenario in the event of a fire is ensured by an algorithm implemented in the alarm central unit and other elements of the system. The implementation of all the system requirements specified within a given procedure algorithm depends on, e.g., an appropriate reliability structure and environmental conditions. The article analyses the operational process of selected FAS, which are operated within a vast transport area. It discusses the actual results of the operational process tests, e.g., repair and damage durations. Next, operational relationship graph, taking into account the conducted operational test, was developed. This enabled the determination of relationships that allow to specify the operating and reliability parameters in terms of a FAS staying in the states distinguished for the research. The FAS test methodology presented in the article, owing to meeting specific performance requirements, can be used in the course of developing a fire scenario and designing systems, taking into account various available technical solutions.