What does 'Vso' symbolize on an airspeed indicator?

'Vso' represents the stall speed of an aircraft in a landing configuration, specifically when the flaps are fully extended. This is a critical airspeed for pilots to understand, as it indicates the minimum speed at which an aircraft can maintain controlled flight during landing. If the aircraft drops below this speed while in the landing configuration, it may stall, leading to a loss of control.

Understanding 'Vso' is essential for ensuring safe landing procedures. It helps pilots determine the appropriate approach speed and recognize when they need to maintain a higher speed to avoid stalling during critical phases of flight. The context of landing configuration is particularly important, as other configurations may have different stall speeds, which influences the handling of the aircraft during approach and landing.

The other choices refer to different speeds relevant to aircraft operations but do not specifically pertain to the stall speed in landing configuration, making 'Vso' distinct in its significance for safe flying practices.