What is a spoiler on an airplane?

• A. A type of wing device that reduces lift at high speed.
• B. High-drag devices that can be raised into the air flowing over an airfoil, reducing lift and increasing drag.
• C. A system used to steer the airplane on the ground.
• D. A mechanism that seals the cabin during flight.

Answer: (B)

Spoilers are wing devices that disrupt the airflow over the wing to spoil lift and create drag. When they’re deployed, they rise into the airstream, which reduces the lift the wing can produce and increases resistance. This dual effect is why they’re used as speed brakes in flight and, after touchdown, as ground spoilers to dump lift and transfer weight to the wheels for more effective braking. They’re not used for steering on the ground, and they aren’t meant to seal the cabin. So the description that matches their function best is that they are high-drag devices raised into the airflow that reduce lift and increase drag.