Does the heating of the drain masts depend on the controller ON/OFF state?

The heating of the drain masts does not depend on the controller's ON/OFF state because the heating system operates independently of the controller's settings. This means that even if the controller is off, the heating function for the drain masts is designed to activate automatically under specific conditions, such as freezing temperatures, to ensure that the drains remain functional and do not become obstructed by ice. This independent operation is crucial for maintaining safety and efficiency, especially during critical phases of flight when the aircraft is exposed to adverse weather conditions.

In contrast, other choices suggest varying levels of dependence on the controller's status. However, the heating system is designed to prioritize the operational integrity of the aircraft components, leading to the conclusion that it functions without direct influence from the control system's ON/OFF condition.