What must be the condition of the fuel jettison valve during any part of the jettisoning operation?

The correct answer emphasizes the importance of having the fuel jettison valve in a state that allows flight personnel to close it if necessary. During fuel jettison operations, it is crucial that the crew can control the process to ensure safety and compliance with operational protocols. If circumstances change or if there is an unforeseen issue, the ability to close the valve is critical to avoid potential hazards or to prevent excessive fuel loss.

The focus on safety management in aviation demands that mechanisms, such as valves and switches, be operable and accessible to flight personnel during critical operations. This ensures that the crew can promptly respond to any abnormalities or requirements that arise during the jettisoning process.

Other options focus on aspects that do not prioritize the crew's control over the operation. For example, having the valve remain open continuously, without the option to close it, could lead to safety risks. Similarly, positioning the valve forward or requiring a reset before landing does not adequately address the operational flexibility needed during jettisoning.