Which is the correct symbol for the stalling speed in a specified configuration?

The symbol that represents the stalling speed in a specified configuration is denoted as VS1. This symbol specifically indicates the stall speed of an aircraft at a specific weight and configuration, typically at a standard wing flap setting for that configuration.

Stalling speed is critical for pilots to know because it is the minimum speed at which the aircraft can maintain controlled flight. Understanding this speed helps ensure safety during various phases of flight, particularly during takeoff and landing when the aircraft is close to this critical speed.

The other symbols mentioned refer to different variations of stall speeds but do not specify a stalling speed in a particular configuration. For instance, VSO is the stall speed in a landing configuration, while VS is a general symbol that can denote stall speeds but lacks the specification of the operational context, and VST is not a standard notation used in aviation. Thus, VS1 is the most precise choice for indicating stalling speed in a specified configuration in military and general aviation contexts.