What does the red line on an airspeed indicator represent?

• A. Never-exceed speed
• B. Maneuvering speed
• C. Cruise speed
• D. Best glide speed

Answer: (A)

The red line marks the never-exceed speed, the maximum indicated airspeed you must not exceed in flight. It’s there to protect the airframe from structural overload; pushing beyond it can cause damage or loss of control, especially in dives or rough air. This limit is a fixed safety boundary for the aircraft’s design and is shown as a red indicator to warn you to stay below it at all times.

Maneuvering speed is about the load you can put on the airplane with abrupt control inputs and is not the red-line indicator. Cruise speed and best-glide speed are useful operating speeds but are not the safety limit represented by the red line.