Private Pilot License (PPL) Aerodynamics Practice Exam

In an airspeed indicator, which color represents the lower limit of the green arc?

1. Red

2. Yellow

3. White

4. Green

The correct answer is: Red

The correct answer pertains to the color coding system used in airspeed indicators to convey important information about an aircraft's safe operating speeds. In this system, the green arc signifies the normal operating range for the aircraft, where it can safely fly without risking stalling or exceeding maximum structural limits. The lower limit of the green arc represents the minimum safe airspeed for flight, known as the "stalling speed in a clean configuration." The red color indicates the airspeed below which the aircraft cannot safely operate. It is specifically designated as the "never exceed speed," which is vital to ensure pilots understand the absolute minimum speed to maintain control. Therefore, the lower limit of the green arc is signified by the onset of the red arc, which establishes a boundary between safe and unsafe operational speeds. This understanding is crucial for pilots in maintaining effective control and performance during flight, especially in terms of stall awareness and general safety practices.