What is ground effect?

Ground effect refers to the aerodynamic phenomenon that occurs when an aircraft is flying close to the ground, generally within one wingspan's distance from the surface. In this situation, the airflow around the aircraft is altered, which leads to an increase in lift and a decrease in drag. This occurs due to the interference of the ground with the airflow patterns around the wings. Essentially, the ground limits the extent of the wingtip vortices that are created, allowing for a more efficient flow of air over and under the wings.

When an aircraft is in ground effect, it can become easier to maintain altitude at lower speeds, which is why pilots often notice that they can float along just above the runway or land with a reduced approach speed when close to the ground. This phenomenon is particularly significant during takeoff and landing phases and is a key consideration for pilots when managing airspeed and altitude during these critical flight stages.