When a project experiences a delay that could impact the schedule, the project manager should capture the risk in the risk register. This allows for the documentation of the risk and its potential impact, as well as the planning of appropriate response actions to mitigate the risk. The risk register is a key tool for risk management in projects, as it provides a structured way to track and monitor risks throughout the project lifecycle. By capturing the risk, the project manager can work on preventing the risk from becoming an issue, which aligns with the proactive approach to risk management advocated by PMI.
References: (Project Management Institute. (2021). A Guide to the Project Management Body of Knowledge (PMBOKGuide) - Seventh Edition and Standards. Project Management Institute.)