Ground effect is most prominent at what altitude during landing?

Ground effect is a phenomenon that occurs when an aircraft is operating very close to the surface, particularly during takeoff and landing. It is most prominent at touchdown because the wings are within one wingspan of the ground. This proximity reduces induced drag and increases lift, allowing the aircraft to maintain a better performance profile and often resulting in a smoother landing.

As the aircraft descends and approaches the runway, the airflow around the wings is altered due to the presence of the ground. When the aircraft is at touchdown, it experiences a significant increase in lift due to this ground proximity, which effectively enhances the wing's performance during the critical phase of landing. Achieving optimal lift while minimizing drag at this altitude is essential for controlling the aircraft during landing.

In contrast, at greater altitudes such as 50 feet or 100 feet above the ground, the effects of ground proximity are less pronounced, and the benefits of ground effect are gradually diminished as the aircraft gains altitude. Therefore, the influence of ground effect is most beneficial and pronounced at touchdown, making it a key factor in the landing performance of an aircraft.