Architecture-Led Safety Analysis (ALSA) is a safety analysis method that uses early architecture knowledge to supplement traditional safety analysis techniques to identify faults as early as possible. The method begins by creating a definition of the operational environment within which the system under design will operate. ALSA uses the early architecture knowledge of the system and standardized error guide words to identify hazards in the system. These hazards are analyzed using knowledge of the architecture and safety requirements, intended to mitigate the hazards, that are added to the system’s requirements. ALSA continues its analysis down the full depth of the system implementation hierarchy. As additional implementation details are defined, the hazard analysis is applied to the subcomponents. ALSA also cuts across many of the phases in the development lifecycle. The hazard analysis feeds the requirements definition, architecture definition, and verification and validation phases.