Definition
A wheel braking system that uses hydraulic system pressure, rather than pilot pedal force alone, to apply the brakes. The pilot's pedal movement operates a control valve that meters fluid from the aircraft's main hydraulic system to the brake assemblies, producing the high pressures needed to stop a heavy aircraft.
Plain English
A braking system where the aircraft's hydraulic system does the heavy work of pressing the brakes. The pilot's pedal just tells the system how hard to squeeze.
Context Anchor
Seen in aircraft brake system descriptions, maintenance procedures, and discussions of normal or emergency braking.
Derivation
The term mirrors automotive 'power steering' and 'power brakes' — 'power' here means the work is done by an external power source (the hydraulic system) rather than by muscle. Knowing this signals that the pilot is commanding the brakes, not driving them directly.
Why Pilots Care
They allow larger or heavier aircraft to stop reliably within runway length without requiring extreme pedal force that could cause fatigue or delayed response.
Analogy
Think of turning a faucet: your hand controls the valve, but the water pressure does the actual pushing. In power brakes, the pilot controls the brake pressure, but the hydraulic system supplies the force.
Intuition Check
Power brakes does not mean the engine drives the wheels or that the brakes are automatically stronger. It means an aircraft pressure system supplies the force that applies the wheel brakes.
Example Sentence 1
On transport-category aircraft, power brakes allow the pilot to stop the aircraft using only light pedal pressure.
Example Sentence 2
During landing rollout the pilot applied steady pressure to the power brakes to bring the aircraft to a controlled stop.