Definition
A hinged or extendable surface on an aircraft that, when deployed, increases drag in order to limit the aircraft's airspeed during a descent. Dive brakes are commonly found on gliders, military aircraft, and some high-performance airplanes, and are used to control the rate of descent and prevent the airspeed from exceeding safe limits in a dive.
Plain English
A panel or flap on the aircraft that opens out into the airflow to slow the aircraft down when it is descending steeply.
Context Anchor
Seen in aircraft systems, flight controls, and operating procedures for airplanes designed to descend steeply without gaining too much speed.
Derivation
From 'dive' (a steep descent) and 'brake' (a device that slows motion). The name describes its purpose directly: a brake used during a dive to keep the aircraft from going too fast.
Why Pilots Care
Allows safe, rapid altitude loss without overspeeding the airframe or losing precise control of the approach path.
Analogy
It is like holding your hand flat out of a car window. The hand catches the air and creates resistance, which is what a dive brake does on an aircraft.
Intuition Check
A dive brake is not a wheel brake, and it does not make the aircraft dive. It slows the aircraft in a dive by adding air resistance.
Example Sentence 1
The glider pilot extended the dive brakes to steepen the approach without picking up excess airspeed.
Example Sentence 2
With the dive brakes deployed, the glider descended quickly enough to reach the airfield before losing lift.