Ground effect is most likely to result in which problem?

• A. Becoming airborne before reaching the recommended takeoff speed
• B. Increased stall speed
• C. Reduced stability
• D. Increased drag

Answer: (A)

Ground effect increases lift and reduces induced drag when the wing is very close to the surface. The nearby ground alters the wing’s airflow, suppressing wingtip vortices and downwash, so the wing can generate more lift at a given airspeed. That boost in lift can cause the airplane to lift off at speeds lower than the published takeoff speed, which is why becoming airborne before reaching the recommended takeoff speed is the likely outcome in ground effect. This effect is strongest within about one wingspan of the ground and diminishes as you climb away. Drag does not increase in this situation—induced drag actually decreases—nor does stall speed typically rise; in ground effect, stall behavior is altered but not by an increase in stall speed. Stability isn’t the primary issue associated with ground effect here.