Under which condition would a crew chief stop an explosive operation?

A crew chief would stop an explosive operation under the condition of an unknown visitor entering the area primarily due to safety and security concerns. When conducting explosive operations, maintaining a secure area is critical to prevent unauthorized access that could lead to accidents or deliberate interference with the operation.

In the presence of an unknown visitor, the crew chief must ensure the safety of all personnel involved, as well as protect sensitive and potentially dangerous materials. The potential risk of harm from an unrecognized individual warrants an immediate halt to operations to assess the situation, verify the visitor's identity, and ensure that the area is secure before continuing with any further explosive activity.

In contrast, scheduled maintenance, inspections, and weather conditions, while also important, do not explicitly necessitate an immediate stoppage of operations due to the same level of direct security risk associated with an unknown individual entering the area. These situations can often be managed without halting the entire operation unless they escalate to a safety issue.