If the OAT is between 4-7°, what happens if no ice accretion is detected for 15 minutes?

When the Outside Air Temperature (OAT) is between 4-7°C and no ice accretion is detected for more than 15 minutes, the correct response is that the armed systems will deactivate. This is a safety measure designed to prevent unnecessary operation of ice protection systems when they are not needed. Ice protection systems are critical when flying in conditions where icing may occur, but if there is no ice formation after the designated monitoring period, it indicates that conditions are clear of ice, allowing the systems to deactivate to conserve energy and reduce wear.

This deactivation helps to ensure that the aircraft operates efficiently while still providing protection when necessary. It also allows pilots to focus on other systems and controls knowing that the ice protection systems are functioning as designed. Therefore, the process is about optimizing performance and safety while responding to actual environmental conditions.