Which stability description applies when the airplane tends to return to its original attitude after a control input?

• A. Neutral longitudinal static stability
• B. Negative static stability
• C. Lateral stability
• D. Positive static stability

Answer: (D)

The important idea is how the airplane responds immediately after a disturbance. If the aircraft tends to return to its original attitude, there is a restoring moment that pushes it back toward the trimmed state. That describes positive static stability. Since the question refers to attitude changes in pitch, this is about longitudinal stability (pitch about the lateral axis). If the aircraft neither returns nor diverges, that would be neutral longitudinal static stability; if it diverged away, that would be negative static stability. The restoring tendency comes from the aircraft’s aerodynamics, such as tail forces creating a nose-down or nose-up moment to bring the nose back to its original position.