What does the red radial line on an airspeed indicator represent?

The red radial line on an airspeed indicator indicates the never-exceed speed, which is a critical limit for safe aircraft operation. This speed, often marked in red, serves as a warning to pilots that exceeding it may lead to structural failure or loss of control of the aircraft. The never-exceed speed is particularly important during maneuvers or in situations involving turbulence, as flying above this speed significantly elevates the risk of adverse aerodynamic effects and potential damage to the aircraft.

Understanding the significance of this indicator helps pilots manage their speed effectively and ensure safe operational practices. Properly adhering to the never-exceed speed is crucial for maintaining the aircraft's structural integrity and ensuring the safety of both the crew and passengers.