What is the primary difference between static and dynamic stability?

The primary distinction lies in the definitions of static and dynamic stability in aviation. Static stability pertains to an aircraft's initial response to disturbances from its equilibrium position; it assesses how the aircraft reacts immediately after any deviation from its intended flight path, such as a gust of wind or a change in control input. For instance, if an aircraft is perturbed and tends to return to its original position, it is said to have positive static stability.

On the other hand, dynamic stability incorporates the aircraft's behavior over time following the initial response. It evaluates how the aircraft's motion evolves after that initial disturbance, taking into account oscillations and dampening effects. An aircraft can be statically stable but dynamically unstable if it continues to oscillate with increasing amplitude over time after the initial perturbation.

This clear differentiation highlights why the second choice accurately reflects the fundamental aspects of static versus dynamic stability in flight dynamics.