What is displayed in the green arc on an airspeed indicator?

The green arc on an airspeed indicator indicates the aircraft's normal operating range for speeds. This range represents the speeds at which the aircraft can safely operate under a variety of conditions without risking damage or loss of control. Generally, it encompasses the speeds suitable for takeoff, cruise, and landing while maintaining adequate control. Operating outside of this arc can lead to potential hazards, as the speeds are deemed safe for normal flight operations.

In contrast, the other options refer to specific points or ranges that are not characterized by the green arc. The flap operating speed is usually indicated by a different color, often found in the yellow arc. The maximum allowable speed typically is represented by the red radial line on the airspeed indicator and is not within the normal operating range. The stall speed with flaps extended is also identified separately, usually with a specific marking, rather than being part of the green arc. Therefore, identifying the green arc as the normal operating range aids pilots in ensuring they are operating within safe speed limits.