What is the consequence of a defective wheel speed sensor on braking control?

• A. Braking may be less stable or misapplied
• B. Braking becomes stronger and more stable
• C. Autobrake is unaffected
• D. The aircraft cannot deploy landing gear

Answer: (A)

Braking control depends on real-time data from wheel speed sensors to know how fast each wheel is turning and whether it is about to skid. The anti-skid system compares wheel speeds and deceleration to modulate hydraulic braking pressure so you don’t lock a wheel. If a wheel speed sensor is defective, the control unit loses an accurate input for that wheel. With unreliable or missing data, the system can’t correctly gauge wheel slip, so it may apply too much or too little brake pressure, or brake one wheel differently from the others. The result is braking that is less stable and potentially misapplied, especially during touchdown or when autobrake is active. The issue isn’t that braking becomes stronger or that autobrake is unaffected; instead, the loss of accurate wheel speed data leads to unstable or improper braking.