In ground effect, which statement is correct?

• A. The downwash angle increases
• B. The induced angle of attack decreases
• C. The airspeed remains constant
• D. The lift coefficient increases

Answer: (B)

In ground effect, the wing’s induced flow is altered by the presence of the ground. The wing normally creates a strong downwash behind it, which corresponds to an induced angle of attack that adds to the geometric angle at which the wing meets the oncoming air. When the wing is close to the ground, the ground interrupts and weakens those wingtip vortices, so the downward deflection of the air behind the wing is reduced. That means the induced angle of attack becomes smaller.

Because the induced angle of attack is smaller, the wing effectively sees a larger portion of its geometric angle of attack as actual attack, which helps explain why lift can increase in ground effect for the same flight condition and also why induced drag decreases. The other statements don’t align with what happens to the flow: the downwash does not increase in ground effect, and while the overall lift characteristics change, the primary immediate change described by the option is the reduction in the induced angle of attack.