The stability around the longitudinal axis is called what?

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

Answer: (A)

Stability around the nose-to-tail axis is roll stability, which is commonly referred to as lateral stability. The longitudinal axis runs from the front to the back of the airplane, and rotation about that axis produces a roll (one wing down, one wing up). Lateral stability is the aircraft’s tendency to resist rolling disturbances or to return to wings-level after a gust or bank. This is why the term lateral stability fits: it describes how the aircraft behaves in the lateral plane (left-right roll) and its tendency to settle back to level flight.

For context, directional stability is about yaw around the vertical axis (left-right turning), and longitudinal stability is about pitch around the lateral axis (nose-up or nose-down motion).