What is the phenomenon called when the ground or water surface interferes with the airflow around an aircraft in flight?

What is the phenomenon called when the ground or water surface interferes with the airflow around an aircraft in flight?

• A. Ground Effect
• B. Induced Drag
• C. Stall
• D. Turbulence

Answer: (A)

Ground effect is the phenomenon at play when an aircraft is very close to the surface and the surrounding airflow is altered by the presence of the ground or a body of water. The air that would normally roll off the wingtips and create strong downwash is disrupted by the nearby surface, effectively mirroring the wing's circulation. This weakens the wingtip vortices and reduces downwash, so the wing can generate more lift for the same angle of attack and with less induced drag. That makes takeoffs shorter and landings smoother when near the surface, and the effect is strongest within about a wingspan of the ground, fading as you climb higher. Other terms describe different issues: induced drag is the drag produced by lifting, which is reduced in ground effect but is not the triggering phenomenon; stall is a loss of lift at high angles of attack; turbulence is irregular air movement.

Ground effect is the phenomenon at play when an aircraft is very close to the surface and the surrounding airflow is altered by the presence of the ground or a body of water. The air that would normally roll off the wingtips and create strong downwash is disrupted by the nearby surface, effectively mirroring the wing's circulation. This weakens the wingtip vortices and reduces downwash, so the wing can generate more lift for the same angle of attack and with less induced drag. That makes takeoffs shorter and landings smoother when near the surface, and the effect is strongest within about a wingspan of the ground, fading as you climb higher.

Other terms describe different issues: induced drag is the drag produced by lifting, which is reduced in ground effect but is not the triggering phenomenon; stall is a loss of lift at high angles of attack; turbulence is irregular air movement.