What is the effect of spoilers/dive brakes on speed and descent rate?

• A. Spoilers increase drag and lift, enabling steeper descents.
• B. Spoilers increase drag and reduce lift, enabling steeper descents and lower speeds.
• C. Spoilers decrease drag and increase lift, improving descent rate.
• D. Spoilers have no effect on descent rate.

Answer: (B)

Spoilers or dive brakes disrupt the smooth airflow over the wing, increasing drag and reducing lift. That combination changes the flight path: with more drag, the airplane sinks more quickly, so you can achieve a steeper descent without having to accelerate. At the same time, the loss of lift means you’re not generating as much upward force, which helps you maintain a controlled, lower airspeed if you manage thrust accordingly. This dual effect—more drag and less lift—lets you descend steeply while keeping the speed in check, which is why the best description is that spoilers increase drag and reduce lift, enabling steeper descents and lower speeds.