In the event of a compass error, what should a pilot check?

When a pilot encounters a compass error, checking the heading indicator's accuracy is essential because the heading indicator provides critical information for navigation and situational awareness. If there is a discrepancy between the magnetic compass and the heading indicator, it may lead to incorrect navigation decisions. The heading indicator relies on various calibration methods, including magnetic inputs, and the pilot must ensure it reflects the true heading of the aircraft accurately.

While proximity to navigational aids, magnetometer calibration, and the aircraft's operating weight can play roles in overall navigation and aircraft performance, they are not directly relevant to resolving compass errors in real-time. Ensuring the heading indicator's accuracy allows the pilot to adjust the flight path accordingly and maintain proper flight direction, especially in instrument flight situations where visual references may be limited.