When an aeroplane enters ground effect at constant IAS, what happens to the induced drag?

When an aeroplane enters ground effect while maintaining a constant indicated airspeed (IAS), the induced drag reduces. Ground effect refers to the phenomenon occurring when an aircraft is close to a surface, such as the ground or water, which alters the airflow patterns around the aircraft's wings.

In ground effect, the proximity to the ground interferes with the wings' downwash, which is the air deflected downwards by the wings. This alteration decreases the effective angle at which the air interacts with the wing, leading to an improvement in lift-to-drag ratio. Consequently, as lift is generated more efficiently, the amount of induced drag, which is related to the lift produced, is reduced.

By maintaining a constant IAS, the aircraft is able to achieve lift more efficiently due to this reduction in drag, making flight close to the ground more economical and stable. This phenomenon explains why pilots often experience a smoother transition during takeoff or landing phases when operating in ground effect.