ATPL Airframe Practice Test

The wheel speed sensor is essential for providing the anti-skid control unit with accurate data about the rotational speed of each wheel during braking. This information is critical because it allows the anti-skid system to determine if any wheel is about to lock up. When the system detects that a wheel is spinning slower than others—indicating potential skid—the control unit can regulate brake pressure to maintain traction and prevent tire skidding.

By continuously monitoring the wheel speeds, the anti-skid system can make real-time adjustments to the brake pressure, thus enhancing both safety and control during landing and other braking scenarios. This functionality is vital for ensuring the aircraft can stop effectively while maintaining directional control.

In contrast, the other devices mentioned do not directly supply the necessary information specific to wheel rotation needed for anti-skid functioning. The airspeed indicator provides data about the speed of the aircraft through the air, while the pilot-static system measures altitude and air pressure. A hydraulic pressure sensor monitors the hydraulic fluid pressure but does not relate specifically to wheel speed.