What describes the stability of an aircraft about its lateral axis?

The stability of an aircraft about its lateral axis is referred to as longitudinal stability. This aspect of stability is primarily concerned with how an aircraft responds to disturbances in pitch, meaning how it behaves when its nose moves up or down.

Longitudinal stability ensures that when an aircraft is disturbed, it will naturally return to its original flight configuration without requiring constant pilot input. For example, if the aircraft's nose pitches up due to an increase in angle of attack, a well-designed longitudinally stable aircraft will tend to pitch back down towards its original attitude, promoting overall flight stability.

Understanding this stability is crucial for pilots as it affects aircraft handling and performance during various flight maneuvers. In contrast, static stability refers to the initial response of the aircraft to a disturbance, while dynamic stability refers to how the response changes over time. Directional stability, on the other hand, pertains to the stability of the aircraft in the yaw axis, focusing on its responsiveness to lateral disturbances. Hence, longitudinal stability is specifically associated with the aircraft's behavior around the lateral axis, making it the correct answer.