The heart of the FBW concept is the use of triple redundancy for all hardware resources: the computing system, airplane electrical power, hydraulic power and communication paths. The multiple redundant hardware is required to meet the numerical safety requirements. Hardware redundancy can be relied upon only if hardware faults can be contained; fail-passive electronics are necessary building blocks for the FBW systems. In addition, the FBW computer architecture must consider other fault tolerance issues: generic errors, common mode faults, near-coincidence faults and dissimilarity