Aircraft on-board systems architectures are defined by the subsystems and the connections among them. The requisites for these connections are not directly established in the certification specifications but they are indi- rectly derived from other requirements. In addition, generally only a small number of architectures taken from previous studies are considered when performing on-board systems design. This makes it difficult to generate certifiable connections when assessing an extensive number of architectures. Considering certification aspects during early design stages can be used as a filter to save computational time by calculating only potentially certifiable architectures. The aim of this paper is to develop a methodology to automatically assess certifi- cation requirements of on-board systems architectures that come from the certification specifications. One part of the methodology consists of a list of requirements to be considered to define the connections among on-board systems during architecture design in order to find safe and certifiable solutions. The other part is focused on the automation of the reliability block diagram technique. This is needed in order to verify safety assessment requirements which have a high influence on the architectures and connections. The advantages of this study are mainly the capability to assess multiple architectures and to verify certification requirements during early design stages. A full automation for this process was achieved and showed through an example test case. An aeronautical application case is also shown. This analysis could also be implemented for the study of innovative on-board systems architectures.