Which statement correctly describes static stability and dynamic stability in pitch?

• A. Dynamic stability refers to the instantaneous initial response; static stability refers to time-based decay.
• B. Static stability describes how motion decays over time; dynamic stability is the initial response.
• C. Static stability is the initial tendency to return to trim after a disturbance; dynamic stability describes how the motion decays over time.
• D. Static stability depends on weight; dynamic stability does not.

Answer: (C)

Static stability in pitch is about the immediate tendency after a disturbance to return toward the trimmed condition. If the nose-up or nose-down nudge is met with a restoring pitching moment, the aircraft has positive static stability. Dynamic stability then looks at what happens as time passes: do the resulting motions die away (damped), continue at the same amplitude (neutral), or grow (unstable)?

Therefore, the statement that matches is that static stability describes the initial tendency to return to trim after a disturbance, while dynamic stability describes how the motion decays over time. The other options mix up which aspect refers to the initial response versus the time history, or introduce weight as the decisive factor, which isn’t how these stability concepts are defined.