This paper examines how Stop-Work Authority (SWA) and speak-up practices can be embedded in high-risk engineering operations through consistent leadership reinforcement. Using a practice-based case approach, it draws on operational records from the early implementation period, including observation logs, stop-work reports, toolbox talks, reporting activity, and HSE coordination minutes. The paper shows how predictable leader support, blame-free intervention, verification before restart, and visible follow-up helped normalise earlier escalation, hierarchy-neutral challenge, and preventive use of SWA. It contributes a practical explanation of how formal stop-work authority becomes routine operational behaviour through safety leadership, psychological safety, and a credible speak-up culture.