When is the anti-skid system deactivated?

• A. Wheelspeed below 10 kt
• B. Wheelspeed above 60 kt
• C. Brakes released
• D. At takeoff

Answer: (A)

Anti-skid works by measuring wheel speeds and modulating brake pressure to prevent tire lock during braking. It needs reliable, meaningful data from the wheels to decide when and how hard to brake. When the aircraft is moving very slowly on the ground, the wheel-speed signals become unreliable and the braking corrections aren’t helpful; in fact, they can cause uneven braking or abrupt changes. To avoid that, the system automatically deactivates at very low ground speeds—roughly around 10 knots. Once you accelerate above that speed again (or you’re braking from a higher speed), the anti-skid can re-engage and protect against skidding.

That’s why the correct understanding is that anti-skid is deactivated when wheel speed falls below about 10 knots. The other options don’t fit because anti-skid isn’t specifically tied to a takeoff moment, nor to simply having brakes released, and it isn’t automatically turned off only at high speeds like 60 knots or during takeoff.