Stability in the vertical axis tends to drive the sideslip angle toward zero. The most dynamic stability about the vertical axis on modern jet transports is provided by:

The most dynamic stability about the vertical axis on modern jet transports is provided by an active stability augmentation system or yaw damper. This system is designed to automatically sense and correct for unwanted yaw motions that occur due to various disturbances, such as wind gusts or asymmetrical thrust (for example, during engine failure or in turbulence).

When the aircraft experiences a sideslip due to these factors, the yaw damper can quickly and effectively apply rudder inputs to counteract the yaw, helping to stabilize the aircraft and drive the sideslip angle back towards zero. This quick reaction not only enhances the aircraft's stability in the vertical axis but also improves overall handling characteristics by providing a smoother flight experience.

While the vertical fin and rudder also contribute to directional stability, they do so mainly through passive means—relying on aerodynamic forces that act on the aircraft's structure. Pilot input can assist in maintaining straight flight, but it is often slower and less precise than the automatic corrections performed by the yaw damper. Therefore, the active stability augmentation system is the most effective mechanism for achieving dynamic stability in the vertical axis of modern jet transports.