In ground effect, induced drag does what as the aircraft nears the surface?

• A. Decreases
• B. Increases
• C. Remains the same
• D. Becomes unpredictable

Answer: (A)

As you get closer to the surface, induced drag decreases. When a wing produces lift, it creates wingtip vortices and downwash that waste energy as drag. The ground interferes with those vortices and downwash, effectively creating an opposite “image” vortex system that partly cancels some of the downwash. This makes the lift force more efficient for the same angle of attack, so less energy is lost to vortices—i.e., less induced drag. The effect is most noticeable within about one wingspan of the ground; farther away, the induced drag returns to its normal value. This reduced drag near the surface also helps improve lift-to-drag efficiency during low-altitude flight, such as approaches and short-field landings.