Active STPA : integration of hazard analysis into a Safety Management System Framework

Abstract

This dissertation describes a new approach to integrate a hazard analysis into Safety Management Systems (SMS). This new engineering process guides safety managers and analysts in the identification of a migration toward states of higher risk. The solution is the use of an active version of STPA (Systems-Theoretic Process Analysis), a hazard analysis tool based on Systems-Theoretic Accident Model and Processes (STAMP). The Active STPA uses data collected during operations, such as Flight Data Monitoring events and voluntary reporting, to identify leading indicators of increasing risk. The events are compared with the STPA. The discrepancies lead to a reasoning about previous assumptions on human behavior and the environment in which the system operates. New defenses are identified and implemented. The output of the process is a set of new defenses for prevention and mitigation that will enforce the requirements and constraints generated by the STPA, allowing the generation of cumulative knowledge on system behavior over time. The feedback on SMS activities allows targeted safety improvement activities and provides qualitative information for hazard management integrating Active STPA into an SMS. Most of the indicators currently in use in the aviation industry are reactive because they measure only parameter exceedances. Active STPA allows a proactive identification of the potential cause of future accidents.