In what scenario should the signal person use an "emergency stop" signal?

Using an "emergency stop" signal is essential in situations where there is immediate danger to personnel or equipment. This signal is a critical safety measure designed to halt all operations quickly if a hazardous condition arises, such as a worker being in close proximity to a moving load or when the equipment is about to cause an accident. Ensuring the signal person can effectively communicate this urgent need for all lifting operations to cease is fundamental in preserving safety on the job site.

While other choices may involve important signals related to the workflow, such as when a lift is completed or when equipment malfunctions, they do not address urgent emergencies that pose a direct risk to safety. Therefore, the emergency stop signal is specifically intended for circumstances where immediate action is required to prevent injury or damage.