What does the red color marking on the airspeed indicator signify?

The red color marking on the airspeed indicator signifies the "Never Exceed" speed, also known as Vne. This marking indicates the maximum speed that an aircraft should never exceed during flight, as surpassing this speed can lead to structural failure or loss of control. The red radial line, often found at the top of the airspeed indicator, serves as a critical warning to pilots, reinforcing the importance of adhering to this limit to ensure safety.

Understanding this marking is essential in the context of flight operations; it is part of the pilot's responsibility to monitor airspeed and stay within safe limits defined by the aircraft's operating Handbook. In contrast, other color markings on the airspeed indicator represent different ranges of operation, but none carry the same critical level of importance as the red marking, which signifies a hard limit that must not be exceeded.