FAA Ground School Practice Test

What does the red line on an airspeed indicator represent?

1. Stalling speed

2. Best rate of climb speed

3. Never-exceed speed

4. Landing gear operating speed

The correct answer is: Never-exceed speed

The red line on an airspeed indicator signifies the never-exceed speed, which is the maximum speed that an aircraft can safely fly without risking structural damage. This critical speed is often marked in red because it is a vital limitation that pilots must adhere to during all phases of flight. Exceeding this speed can lead to potential catastrophic failures such as control surface flutter or structural failure of the aircraft. Understanding the significance of the never-exceed speed is crucial for pilots, as it establishes a clear boundary that helps ensure safety and the integrity of the aircraft. The other values indicated on the airspeed indicator—such as stalling speed, best rate of climb speed, and landing gear operating speed—are essential for safe operation but are represented by different markings on the indicator, often in yellow or white instead of red, which serves to highlight the utmost importance of the never-exceed speed.