Definition
Moveable aerodynamic surfaces (typically panels on the wings or fuselage) that can be extended into the airstream to increase drag, allowing the aircraft to slow down or descend more rapidly without significantly changing pitch attitude or engine power.
Plain English
Panels the pilot can extend out into the airflow to create extra drag so the aircraft slows down or comes down faster.
Context Anchor
Seen in aircraft systems, descent planning, approach procedures, and cockpit control discussions for aircraft equipped with speed brakes.
Derivation
The term comes from the ordinary words “speed” and “brake.” In aviation, the “brake” action is not wheel friction; it is extra air resistance created by a surface sticking into the airflow.
Why Pilots Care
They provide precise speed control on descent and approach, helping the aircraft stay on profile, avoid excessive airspeed, and stabilize without relying solely on thrust or attitude changes.
Analogy
They work a little like putting your hand flat out of a moving car window: the hand catches more air and creates resistance. Speed brakes do that in a controlled way on an aircraft.
Intuition Check
Do not assume speed brakes are the same as wheel brakes. Wheel brakes slow the aircraft on the ground; speed brakes help slow the aircraft in the air by creating drag.
Example Sentence 1
On descent from cruise, the pilot extended the speed brakes to lose altitude quickly without pulling the power back to idle.
Example Sentence 2
On final approach the crew used speed brakes briefly to stay within the target airspeed range.