Stability about the aircraft's longitudinal axis is called which type of stability?

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

Answer: (B)

Stability about the longitudinal axis is roll stability. The longitudinal axis runs from the nose to the tail, so movements about this axis are rolling motions. Longitudinal stability describes the aircraft’s tendency to resist disturbances that cause rolling and to return to a steady roll angle, thanks to design features like dihedral, wing and tailplane effects, and damping from the horizontal stabilizer.

In contrast, stability about the lateral axis governs pitch (nose up or down) and stability about the vertical axis governs yaw (left or right about the vertical). So the term that specifically names stability about the nose-to-tail axis is longitudinal stability.