What does the term "ground effect" refer to?

Ground effect refers to the aerodynamic phenomenon that occurs when an aircraft is flying close to the ground, typically within a wingspan's distance from the surface. In this situation, the airflow around the wings is altered due to the proximity of the ground, leading to an increase in lift and a decrease in drag.

When an aircraft approaches the ground, the pressure difference above and below the wings becomes more pronounced, allowing the wings to produce lift more efficiently. This increased lift is beneficial during takeoff and landing, as it allows the aircraft to become airborne with a shorter ground roll and enables smoother landings due to the reduced stall speed. The decrease in induced drag also allows for better performance during this critical phase of flight.

Understanding ground effect is crucial for pilots, particularly when making landing approaches or during takeoff. Misjudging the effects can lead to challenges in controlling the aircraft at low altitudes.