What instrument is used to measure airspeed?

The pitot tube and airspeed indicator work together to measure airspeed in an aircraft. The pitot tube, which is mounted on the aircraft's exterior, captures the dynamic pressure of the air as the aircraft moves through it. This dynamic pressure is then compared to the static pressure (measured from a static port) to calculate the airspeed.

The airspeed indicator takes this information and displays it to the pilots, usually in knots or miles per hour. This accurate measurement of airspeed is crucial for safe aircraft operation, as it informs pilots about their speed relative to the surrounding air, which is essential for maintaining control and executing maneuvers.

Understanding the roles of the other instruments highlights why they are not suitable for measuring airspeed. A barometer measures atmospheric pressure, an attitude indicator displays the aircraft's orientation relative to the horizon, and a vertical speed indicator shows the rate of climb or descent. None of these instruments provide a measurement of airspeed, which is why the combination of the pitot tube and airspeed indicator is the correct answer.