What conditions necessitate having the wing anti-ice system ON during takeoff?

The wing anti-ice system must be activated during takeoff specifically in icing conditions or when there is detectable wing contamination. This is crucial because ice accumulation on the wings can significantly alter the aerodynamic properties of the aircraft, leading to reduced lift and increased drag, which can compromise flight safety.

Activating the wing anti-ice system ensures that any ice that may have formed on the leading edges of the wings is melted away, maintaining optimal airflow over the wings and preventing dangerous situations during the critical takeoff phase. This requirement is guided by both the aircraft's operating procedures and safety protocols designed to mitigate the risks associated with ice during flight.

Other conditions, such as low visibility or high winds, while they may present challenges during takeoff, do not inherently necessitate the use of the wing anti-ice system. It's the specific threat of icing conditions and ice contamination that directly impacts the aircraft's performance and safety, highlighting the importance of the selected answer.