Upon leaving ground effect after take-off, what is the expected aircraft behavior?

Upon leaving ground effect after take-off, the expected behavior of an aircraft is characterized by a nose-up pitch and a decrease in longitudinal stability. This phenomenon occurs because, while in ground effect, the aircraft experiences a significant increase in lift due to the proximity of the ground, which helps reduce induced drag and alters the airflow around the wings.

When the aircraft ascends out of ground effect, the lift generated decreases as the influence of the ground diminishes. The abrupt change in airflow characteristics can lead to a temporary imbalance in forces acting on the aircraft, which causes it to pitch up as it exits this beneficial zone. Additionally, the decrease in longitudinal stability can result from the altered lift-to-drag ratio, which can make it more sensitive to changes in pitch attitude. This requires careful control inputs from the pilot to maintain the desired flight path after take-off.

This behavior underscores the importance of understanding the effects of ground effect on aircraft performance and stability, especially during the critical phase of take-off and initial climb.