What action is necessary immediately before takeoff in non-icing conditions?

Turning the wing anti-ice OFF immediately before takeoff in non-icing conditions is critical. This system is designed to prevent ice accumulation on the wings, which is crucial in icing conditions for maintaining optimal aerodynamic performance. However, in non-icing conditions, the use of wing anti-ice can actually reduce lift and increase drag, impairing the aircraft's takeoff performance.

Ensuring that the anti-ice system is off helps preserve the aircraft's efficiency and performance parameters that are necessary for a proper takeoff. If inadvertently left on, it could lead to unnecessary power demands from the engines and may adversely affect the aircraft's weight and balance during takeoff.

In contrast, checking fuel levels, confirming all systems are online, and preparing for descent, while important pre-flight actions, do not specifically address the need to manage the aircraft's performance relevant to the takeoff phase, especially concerning non-icing conditions.