Final answer:
Pilots should check the heading indicator against the magnetic compass regularly, usually every 15 minutes, to ensure accurate navigation.
Step-by-step explanation:
To maintain accurate navigation, pilots should routinely check the heading indicator and ensure it's aligned with the magnetic compass. The magnetic compass aligns with Earth's magnetic field, which functions similarly to that around a bar magnet. In an aircraft, due to precession, the heading indicator may gradually drift from the true magnetic heading.
Therefore, it's essential to frequently compare the heading indicator to the magnetic compass, which is not subject to the same error, and make adjustments as necessary. This process is typically done every 15 minutes or as needed, depending on the aircraft's equipment and the length of the flight.