What does the term "ground effect" refer to?

The term "ground effect" refers specifically to the increased lift experienced by an aircraft when it is in close proximity to the ground. This phenomenon occurs typically when an aircraft is within one wingspan's distance of the ground. In this scenario, the airflow around the wings is altered due to the proximity of the ground, leading to a reduction in induced drag and an increase in lift.

As the aircraft approaches the ground during landing or takeoff, the high-pressure air beneath the wings cannot escape easily, which enhances the lift produced by the wings. This effect allows aircraft to fly more efficiently near the surface and contributes to the ability to perform short takeoffs and landings.

By understanding ground effect, pilots can better manage their performance during critical phases of flight, especially during takeoff and landing, where maintaining adequate lift is crucial.