What does VSO represent?

VSO represents the stall speed of an aircraft in the landing configuration. This speed is crucial for pilots to know because it directly relates to the safe operation of the aircraft during approach and landing phases. When the aircraft is in the landing configuration, which typically refers to flaps being extended and potentially other aerodynamic surfaces being modified, the stall speed decreases.

Understanding VSO is vital because it helps pilots determine the threshold for safe flight operations as they approach and land. Operating below this speed can lead to an aerodynamic stall, which is particularly dangerous during critical phases of flight, such as landing when the aircraft is close to the ground. Thus, knowing VSO aids in maintaining safe flight margins during these operations.