What is the definition of longitudinal stability?

Longitudinal stability refers specifically to an aircraft's inherent capability to maintain or return to a stable pitch attitude after undergoing disturbances, such as turbulence or maneuvers that affect its orientation. This characteristic of longitudinal stability is essential for ensuring that the aircraft can maintain a steady flight path without excessive pilot input to correct for pitch deviations. In practical terms, when an aircraft experiences a nose-up pitch due to a gust of wind, a stable aircraft will automatically correct itself and revert back to its desired flight attitude.

In the context of the other choices, the ability to maintain speed in level flight relates more to speed control and not to stability regarding pitch. The combination of yaw and roll control pertains to lateral or directional stability rather than longitudinal stability. The effectiveness of ailerons specifically addresses lateral control during maneuvers and does not relate to pitch stability. Thus, option B accurately defines longitudinal stability by emphasizing the self-correcting nature of an aircraft’s pitch attitude.