The availability of avionics display systems plays an important role in flight safety and requires a safety analysis during the design phase. The current safety analysis process is not carried out based on the system design model, so there may be inconsistencies. This paper proposes a model-based safety analysis method using a fault dependent matrix, which can be applied to commonly used system modelling tools such as Enterprise Architect. This article illustrates the utilization of the method by providing the elapsed flight time function, using MATLAB to generate the fault dependent matrix, and then obtaining the availability of the function. This method can be used to aid system safety design and improve system design efficiency.