What must be done if the wing anti-ice system is selected ON for takeoff?

When the wing anti-ice system is selected ON for takeoff, it is imperative to also select the cowl anti-ice system ON. This is because both systems work together to ensure proper de-icing and anti-icing of the aircraft during critical phases of operation like takeoff. The wing anti-ice system is designed to prevent ice accumulation on the leading edges of the wings, while the cowl anti-ice system protects the engines by preventing ice formation in the engine inlets.

Selecting both systems ON is a necessary action to ensure that all potential areas susceptible to ice formation are adequately protected, thereby enhancing safety in critical phases of flight where ice can significantly affect aircraft performance.