THESIS DEFENSE of Raphaël CHIRAC - December 19, 2024

This study explores the perception of risks by aircraft maintenance engineers, looking at the limits of an exclusively regulatory approach to safety. It answers three questions: how do mechanics perceive risks (probability, severity, immediacy)? What factors influence this perception? And is there a difference between the risks to mechanics’ health and those to aircraft airworthiness? A taxonomy of hazards was established and experimentally validated, revealing a common representation of hazards among the participants (engineers and mechanics). However, confusion persists between the notions of hazard, risk and safety measure, requiring a clear definition to guarantee safety. A risk perception model was then tested, highlighting the influence of hazard characteristics, engineers’ experiences and the operational context. The study recommends better communication and training to harmonise risk perception and enhance operational safety.