Under what condition is anti-skid inoperative during takeoff?

The correct answer is that anti-skid is inoperative when the system itself is inoperative. This means that if there’s a failure in the anti-skid system, it would be unable to function properly, making it ineffective during takeoff. In such cases, pilots must rely on their manual braking skills and exercise caution to avoid skidding, particularly during wet or slippery runway conditions.

The other conditions listed do not specifically cause the anti-skid system to become inoperative. Wet runway conditions may affect braking effectiveness, but they do not disable the anti-skid system. Similarly, the presence of windshear warnings alerts pilots to potential hazards during takeoff, but it does not impact the functionality of the anti-skid system. A clear runway indicates safe conditions but does not imply that the anti-skid system is functioning if it is not operational by default. Therefore, understanding the direct link between the inoperative status of the anti-skid system and its impact on takeoff safety is critical.