What must be on when in icing conditions or when ICE is annunciated by the ice detection system?

In the CRJ 200, when faced with icing conditions or when the ice detection system indicates the presence of ice (through the ICE annunciation), it is crucial to ensure that the engine cowl anti-ice is activated. The engine cowl anti-ice system is designed to prevent ice formation on the engine inlets, which is vital for maintaining engine performance and preventing any interruptions that could lead to engine malfunction or failure. Properly functioning engine intake is essential for maintaining optimal engine power and efficiency during conditions where ice could otherwise form.

While the wing anti-ice, cockpit heat, and cabin heat systems also contribute to safety and comfort, they address different areas of potential icing. The wing anti-ice system, for example, is particularly important for maintaining lift and stall characteristics, but it is not the primary concern when the ICE annunciation is activated. The cockpit and cabin heat systems are focused on providing thermal comfort to the crew and passengers, rather than directly preventing icing on critical aircraft components. Therefore, activating the engine cowl anti-ice is the appropriate response to mitigate the risk associated with in-flight icing scenarios.