A computer implemented method for analyzing and designing a physical system architecture of a safety-critical system, SYS, wherein a physical system analysis model (PSYS-AM) representing the physical system architecture, PSYS-A, of said safety-critical system, SYS, is modified incrementally until calculated failure rates, λ P FM , of failure modes, FM, of said physical system analysis model (PSYS-AM) are less or equal to failure rates, λ F FM , of corresponding failure modes, FM, of a functional system analysis model (FSYS-AM) representing a functional system architecture, FSYS-A, of said safety-critical system, SYS, wherein the functional system architecture, FSYS-A, represents functions, F, of said safety-critical system, SYS, and their interaction, and wherein the physical system architecture, PSYS-A, comprises hardware components, software components and/or embedded software components represented in said physical system analysis model (PSYS-AM), and wherein for each function, F, of the functional system architecture, FSYS-A, a component fault tree(CFT) element is specified having input failure modes (IFM) and/or output failure modes (OFM), wherein for each failure mode, FM, a failure rate, λFFM, is specified which represents a corresponding safety or reliability requirement of said safety-critical system, SYS, and wherein for each function, F, of the functional system architecture, FSYS-A represented by the functional system analysis model (FSYS-AM) associated elements within the physical system architecture, PSYS-A, represented by the physical system analysis model (PSYS-AM) adapted to implement the respective function, F, are specified. wherein a physical system analysis model (PSYS-AM) representing the physical system architecture, PSYS-A, of said safety-critical system, SYS, is modified incrementally until calculated failure rates, λ P FM , of failure modes, FM, of said physical system analysis model (PSYS-AM) are less or equal to failure rates, λ F FM , of corresponding failure modes, FM, of a functional system analysis model (FSYS-AM) representing a functional system architecture, FSYS-A, of said safety-critical system, SYS, wherein the functional system architecture, FSYS-A, represents functions, F, of said safety-critical system, SYS, and their interaction, and wherein the physical system architecture, PSYS-A, comprises hardware components, software components and/or embedded software components represented in said physical system analysis model (PSYS-AM), and wherein for each function, F, of the functional system architecture, FSYS-A, a component fault tree(CFT) element is specified having input failure modes (IFM) and/or output failure modes (OFM), wherein for each failure mode, FM, a failure rate, λFFM, is specified which represents a corresponding safety or reliability requirement of said safety-critical system, SYS, and wherein for each function, F, of the functional system architecture, FSYS-A represented by the functional system analysis model (FSYS-AM) associated elements within the physical system architecture, PSYS-A, represented by the physical system analysis model (PSYS-AM) adapted to implement the respective function, F, are specified. <EOS>