When is floating due to ground effect most realized during an approach to land?

Floating due to ground effect is a phenomenon that occurs when an aircraft is close to the ground, typically within one wingspan's height above the runway surface. Ground effect reduces the induced drag on the aircraft as it nears the surface, allowing it to maintain lift at lower speeds, which can lead to the sensation of "floating" above the runway during landing.

When an aircraft descends to a point less than the length of its wingspan above the surface, it enters this ground effect zone. This is the point where the interference between the airflow over the wings and the ground becomes significant, creating additional lift and decreasing drag, which can cause the aircraft to float over the runway for longer than anticipated if not properly controlled.

In contrast, if the aircraft is above the runway by one wingspan or more, or at a higher altitude, the effects of ground effect are minimal. Furthermore, landing on an uphill runway does not inherently enhance ground effect but instead presents its own challenges, such as a need for increased power or approach adjustments.