Analyze the effect of ground effect on an airplane's lift coefficient (CL) and induced drag coefficient (CDi).

Statement I says: "The lift coefficient CL increases".
When an aeroplane enters ground effect, the airflow around the wings is altered by the proximity of the ground. This reduces the downwash behind the wing, which effectively increases the wing's angle of attack relative to the undisturbed air and improves its efficiency. As a result, for a constant angle of attack, the lift coefficient (CL) increases. This statement is correct.

Statement II says: "The induced drag coefficient CDi increases".
Ground effect significantly reduces the formation and strength of wingtip vortices. Since induced drag is directly related to these vortices, a reduction in their strength leads to a decrease in induced drag. Therefore, the induced drag coefficient (CDi) decreases in ground effect. This statement is incorrect.

• Statement I is correct.
• Statement II is incorrect.

Comparing this to the given options:
A. I is correct, II is correct. (Incorrect)
B. I is incorrect, II is incorrect. (Incorrect)
C. I is correct, II is incorrect. (Correct)
D. I is incorrect, II is correct. (Incorrect)

The correct option is C.

The correct statement about an aeroplane entering ground effect at a constant angle of attack is: