When will the anti-skid system allow braking to occur on landing?

• A. Wheel spin up speed reaches 35 kts or 5 seconds after WOW signal is present.
• B. Only after touchdown.
• C. Only after manual activation.
• D. Never.

Answer: (B)

Anti-skid braking is designed to prevent tire skidding by modulating brake pressure based on wheel-speed data, and it relies on the weight-on-wheels signal to know when the aircraft is on the runway. Because a reliable ground reference is needed for safe braking, the system does not permit braking until touchdown is detected and weight on wheels confirms contact. Once the airplane is on the ground, anti-skid engages automatically, allowing braking while preventing wheel lock. This is why braking is allowed only after touchdown. The other scenarios—requiring manual activation, a fixed speed threshold, or never—don’t match how anti-skid operates in practice.