What type of aircraft stability is affected when an aircraft enters ground effect?

When an aircraft enters ground effect, it primarily impacts longitudinal stability. Ground effect occurs when an aircraft is flying close to a surface, such as the ground or water, significantly altering its aerodynamic characteristics. This phenomenon is primarily due to the increased lift produced and the reduction in induced drag as the aircraft nears the surface.

In longitudinal stability, the aircraft's center of gravity (CG) and the aerodynamic center (AC) play critical roles. When an aircraft is in ground effect, the interaction of the airflow around the wings and the ground changes the lift and drag characteristics, effectively shifting the balance of forces acting on the aircraft. This can lead to changes in pitch behavior, which is a significant element of longitudinal stability.

As the aircraft transitions out of ground effect, it may also experience a momentary change in the stability characteristics, making it essential for pilots to be aware of these changes during takeoff and landing phases. The notion that ground effect influences longitudinal stability is foundational in understanding how aircraft behave in close proximity to the ground and is crucial for safe operation during low-altitude maneuvers.