Which system is primarily responsible for providing data to the heading indicator?

The heading indicator relies heavily on the Attitude Heading Reference System (AHRS) for its data. The AHRS incorporates multiple sensors to determine the aircraft's orientation in three-dimensional space. It calculates the heading based on sensor inputs, which include inertial measurement units, magnetometers, and various algorithms to minimize errors.

These computations enable the heading indicator to function accurately under various operating conditions, including those that may affect magnetic compass readings. In contrast, other options like the GPS system provide positional data, while the magnetic compass is influenced by magnetic variations and may not always provide the most reliable heading information, especially in turning or turbulent situations. The air data computer focuses on altitude, airspeed, and other atmospheric parameters, not directly on the heading information necessary for the heading indicator. Consequently, the AHRS stands out as the primary source for this crucial data.