What does the airspeed indicator measure?

The airspeed indicator measures the speed of the aircraft in relation to the surrounding air, which is essential for various aspects of flight, including performance, safety, and handling characteristics. This measurement is typically derived from dynamic pressure created by the aircraft moving through the air and is displayed on the instrument in knots or miles per hour. Understanding the airflow around the aircraft is critical, as it influences lift, drag, and overall aerodynamic efficiency.

Choices related to other aspects, such as vertical movement, engine performance, or magnetic field actions, do not pertain to what the airspeed indicator is designed to measure, as these are focused on different parameters of flight and aircraft operation.