Stability about the aircraft's vertical axis is called yawing or directional control. This statement refers to which stability term?

• A. Vertical stability
• B. Lateral stability
• C. Longitudinal stability
• D. Directional stability

Answer: (A)

Directional stability is stability about the vertical axis. Yawing is the rotation about the vertical axis, so the term that describes stability in that axis is directional stability. Vertical stability isn’t the standard label for yaw—pitch (nose up/down) is about the lateral axis, not the vertical one. Lateral stability relates to roll about the longitudinal axis, and longitudinal stability relates to pitch about the lateral axis. So the statement points to directional stability.