Definition
A braking technique in which the pilot applies the left or right main wheel brake independently to assist in steering the airplane during taxi, particularly at low speeds when the rudder and nosewheel steering are less effective.
Plain English
Pressing one brake at a time — left or right — to help turn the airplane on the ground. Pressing the left brake helps the airplane turn left; pressing the right brake helps it turn right.
Context Anchor
Encountered during taxi, tight turns, ground handling, and directional control after landing or before takeoff.
Derivation
Differential means 'making a difference between two things.' Here, the difference is between how much braking is applied to the left wheel versus the right wheel. That uneven braking is what produces the turn.
Why Pilots Care
It gives precise ground steering at low speeds where the rudder has little effect, helping prevent runway or taxiway excursions.
Grounding Statement
If the airplane needs to turn left while taxiing, the pilot can apply more left brake so the left wheel slows and the airplane pivots toward that side.
Intuition Check
Differential brakes does not mean a special kind of brake fluid or a more powerful brake. It means the left and right brakes can be used separately or unequally.
Example Sentence 1
During the tight turn into the parking spot, the pilot used differential brakes to bring the airplane around smoothly.
Example Sentence 2
At idle power and low speed, differential braking provided the only effective way to keep the airplane on the centerline.