Which instrument is primarily used for measuring the aircraft's heading?

The heading indicator is the primary instrument used for measuring an aircraft's heading, which is the direction in which the aircraft is pointed relative to magnetic north. It provides pilots with critical information needed for navigation and maintaining the desired course. The heading indicator is calibrated to display the aircraft's heading in degrees, allowing for precise adjustments during flight to stay on track or to follow air traffic control instructions.

In aviation, an accurate heading is essential for effective navigation, especially in situations where visual references are limited, such as in poor weather conditions or at night. The instrument relies on magnetic data and compensates for variations and errors to provide a useful and reliable reading for pilots.

Other instruments mentioned serve different purposes. The altimeter measures altitude and indicates how high the aircraft is above sea level, while the vertical speed indicator shows whether the aircraft is climbing or descending and at what rate. The turn coordinator, on the other hand, helps pilots maintain proper turn rates and coordinated flight but does not provide heading information directly. Each of these instruments plays an important role in flight operations, but only the heading indicator is specifically designed for measuring heading.