Which component is essential for measuring aircraft speed through air?

The pitot tube is the essential component for measuring an aircraft's speed through the air. This device works by measuring the dynamic pressure of the air as the aircraft moves forward. It captures the difference between the total pressure (which includes both static and dynamic pressure) and the static pressure around the aircraft. This difference is then used to calculate the airspeed, which is a critical parameter for flight operations, including takeoff, landing, and navigation.

The other components listed serve different purposes. The attitude indicator is used to display the aircraft's orientation relative to the horizon, providing crucial information for pilots in terms of climbing, descending, or turning. A magnetometer measures the Earth's magnetic field and is used for navigation purposes, particularly in systems like compasses. A gyroscope provides information related to the aircraft's rotation and orientation in space, helping with stability and navigation but does not measure airspeed.