Ground Effect

When an aircraft in flight comes within several feet of the surface, ground or water, a change occurs in the three-dimensional flow pattern around the aircraft because the vertical component of the airflow around the wing is restricted by the surface. This alters the wing’s upwash, downwash, and wingtip vortices. It is due to the interference of the ground (or water) surface with the airflow patterns about the aircraft in flight. As the wing encounters ground effect and is maintained at a constant angle of attack (AOA), there is consequent reduction in the upwash, downwash, and wingtip vortices.

• Ground Effect during Takeoff: During takeoff, an aircraft can become airborne at a lower speed than usual due to the increased lift generated by the ground effect. However, pilots must be cautious not to become overly reliant on the ground effect for lift, as the aircraft may lose some lift once it climbs out of the ground effect, requiring a higher speed to sustain flight.

• Ground Effect during Landing: Ground effect can make an aircraft appear to "float" along the runway during landing, as the reduced drag and increased lift make it easier to maintain flight at lower speeds. Pilots must anticipate this floating tendency and adjust their approach and landing techniques accordingly.