What is the purpose of a "magnetic compass" in aviation?

The purpose of a magnetic compass in aviation is to indicate direction based on the Earth's magnetic field. This instrument is essential for navigation, as it provides pilots with a reliable reference to determine their heading relative to magnetic north. The magnetic compass helps in maintaining the correct course during flight, enabling pilots to navigate accurately and avoid disorientation, particularly in conditions of low visibility or when visual references are obscured.

Understanding the function of the magnetic compass is crucial, as it provides real-time directional information that is fundamental for safe flight operations. In contrast, the other options focus on different aspects of flight operations that the magnetic compass does not address. Altitude indication, fuel level measurement, and flight time tracking rely on different instruments specifically designed for those purposes.