Definition
An aircraft braking system that automatically prevents the wheels from locking up and skidding during landing or rejected takeoff. Sensors detect when a wheel is about to stop rotating while the aircraft is still moving, and the system momentarily releases brake pressure on that wheel so it can spin up again, then reapplies pressure. This cycle repeats many times per second, keeping the tire rolling at the edge of maximum braking effectiveness.
Plain English
A braking system that stops the wheels from locking up. If a wheel starts to slide instead of roll, the system briefly eases off the brake on that wheel so the tire grips the runway again.
Context Anchor
Encountered in aircraft systems descriptions, landing roll discussions, and rejected takeoff braking procedures for aircraft equipped with this system.
Derivation
Skid' means to slide rather than roll. 'Nonskid' simply means 'preventing skidding.' The name describes exactly what the system does: it keeps the tire rolling instead of sliding.
Why Pilots Care
Maintains directional control, shortens stopping distance on wet or contaminated surfaces, and reduces tire damage from skidding.
Analogy
Similar in concept to anti-lock brakes (ABS) on a car. When you stomp the pedal hard, the system pulses the brakes for you so the wheels keep turning instead of locking up.
Intuition Check
Nonskid does not mean the airplane cannot skid. It means the brake system is designed to help prevent a wheel from locking and sliding during braking.
Example Sentence 1
On the wet runway, the nonskid brakes cycled audibly as the captain applied maximum braking after touchdown.
Example Sentence 2
During the high-speed abort, the nonskid system allowed the pilot to brake hard without losing directional control.