What does a magnetometer measure in cockpit instrumentation?

A magnetometer is an instrument used in cockpit instrumentation to measure the strength and direction of magnetic fields. Specifically, within the context of aviation, it assesses the Earth's magnetic field, which allows it to determine the aircraft's heading relative to magnetic north. This information is crucial for navigation and helps pilots maintain proper course, especially when flying in areas where visual references are limited or in poor visibility conditions.

The ability of the magnetometer to detect changes in the magnetic field is what makes it an essential component in updating the heading information displayed on the aircraft's navigation instruments. In contrast, other measurements like temperature, altitude, or speed are provided by different instruments altogether, such as temperature gauges, altimeters, and airspeed indicators, respectively. Each of these instruments serves a unique purpose and provides distinct information vital for safe and effective flight operations.