What should you periodically check to avoid an improperly set heading indicator?

To ensure your heading indicator is correctly set, it's essential to periodically check the magnetic compass. The heading indicator, which is often a gyroscopic instrument, can become misaligned over time due to precession or other factors. By referring to the magnetic compass, which directly reflects the aircraft's orientation relative to the Earth's magnetic field, you can cross-check and verify that the heading indicator is accurate.

The magnetic compass provides a reliable reference that can help identify any discrepancies with the heading indicator. If there's a notable difference between the two, it suggests that adjustments are needed to the heading indicator to ensure accurate navigation.

Verifying against the magnetic compass is a standard practice in piloting, enabling pilots to maintain situational awareness and navigate effectively. Other instruments, like the vertical speed indicator, altimeter, or attitude indicator, do not provide relevant information about heading accuracy and are not suitable for checking the heading indicator's alignment.