A failure-effect validation system comprising at least one processor and associated memory, the failure-effect validation system further comprising: an effects modeler configured to develop a cumulative effects model for failure modes of an aircraft, comprising one or more subsystems or line replaceable units, and by which a model of the aircraft is extendible to include the cumulative effects model to form an extended model, wherein the effects modeler is also configured to develop one or more search targets each of which represents cumulative effects of a failure mode and includes logical expressions of notable hazards, the notable hazards comprising threshold counts of aircraft-level and subsystem-level hazards, and: crew workload, defined to include: a count of alert messages that are generated in response to a hazard or failure mode, a count of compensatory actions or pages of compensatory actions, and a time to complete the compensatory actions, the compensatory actions comprising checklists or paginated documents of crew procedures or non-normal operating procedures, a safety margin between expected usage and an unsafe condition, and physiological effects, the physiological effects comprising measures of one or more of cabin pressure, temperature, light levels, cabin-visibility levels or breathability; and a model analysis system coupled to the effects modeler and configured to perform an automated analysis including a graph search of possible states of the extended model to locate one or more search targets, the automated analysis being performed to identify cumulative effects, beginning with one or more originating system-level failure effects that lead to an aircraft-level failure mode, of at least some of the failure modes, the system level failure effects comprising at least one of hydraulic effects, navigational effects and avionics effects, the failure modes comprising malfunction, degradation or failure, and results of which are displayable in a layout to enable an assessment of the cumulative effects. an effects modeler configured to develop a cumulative effects model for failure modes of an aircraft, comprising one or more subsystems or line replaceable units, and by which a model of the aircraft is extendible to include the cumulative effects model to form an extended model, wherein the effects modeler is also configured to develop one or more search targets each of which represents cumulative effects of a failure mode and includes logical expressions of notable hazards, the notable hazards comprising threshold counts of aircraft-level and subsystem-level hazards, and: crew workload, defined to include: a count of alert messages that are generated in response to a hazard or failure mode, a count of compensatory actions or pages of compensatory actions, and a time to complete the compensatory actions, the compensatory actions comprising checklists or paginated documents of crew procedures or non-normal operating procedures, a safety margin between expected usage and an unsafe condition, and physiological effects, the physiological effects comprising measures of one or more of cabin pressure, temperature, light levels, cabin-visibility levels or breathability; and a count of alert messages that are generated in response to a hazard or failure mode, a count of compensatory actions or pages of compensatory actions, and a time to complete the compensatory actions, the compensatory actions comprising checklists or paginated documents of crew procedures or non-normal operating procedures, a safety margin between expected usage and an unsafe condition, and physiological effects, the physiological effects comprising measures of one or more of cabin pressure, temperature, light levels, cabin-visibility levels or breathability; and a model analysis system coupled to the effects modeler and configured to perform an automated analysis including a graph search of possible states of the extended model to locate one or more search targets, the automated analysis being performed to identify cumulative effects, beginning with one or more originating system-level failure effects that lead to an aircraft-level failure mode, of at least some of the failure modes, the system level failure effects comprising at least one of hydraulic effects, navigational effects and avionics effects, the failure modes comprising malfunction, degradation or failure, and results of which are displayable in a layout to enable an assessment of the cumulative effects.