Which statement best describes dynamic stability in pitch motion?

• A. It refers to the initial response to a disturbance.
• B. It describes how quickly the aircraft returns to trim immediately after disturbance.
• C. It describes how the oscillations persist indefinitely.
• D. It describes how the oscillations damp out over time.

Answer: (D)

Dynamic stability looks at how the aircraft’s pitch motion behaves after a disturbance over time. The key idea is the long-term behavior of the oscillations, not just the immediate response. If the pitch oscillations die away with time, the aircraft is dynamically stable because the energy from the disturbance is damped and the aircraft returns to its trimmed state. If the oscillations persist with the same amplitude, that would be neutral dynamic stability; if they grow, it would be dynamic instability. So the description that the oscillations damp out over time best captures dynamic stability in pitch.