When Magnetometers (And Compasses) Go Bad

The latest-technology glass panels do many more things than the old, tried-and-true “steam gauges” with which many of us grew up. Through the “magic” of a software-driven display supported by various sensors, modern flight instrumentation can provide easy-to-read attitude information and a wealth of other data that simply wasn’t available before. But there’s no free lunch. Along with their additional capabilities and accuracy, glass panels also bring different failure modes to the cockpit. One of these new-tech failure modes involves the way in which they determine the aircraft’s heading, along with other information, most of which firmly belongs in the nice-to-have-but-not-critical category. In many situations, losing heading information isn’t the end of the world—especially if GPS navigation remains available—but it can have a ripple effect on the panel’s various other systems and capabilities. I recently learned the hard way how failure of the heading sensor(s), usually a magnetometer, may not be a failure at all, depending on how the equipment is designed and installed.

Key Takeaways:

• Modern glass cockpit systems introduce new failure modes, such as erroneous heading indications from magnetometers, despite their advanced capabilities.
• These heading inaccuracies can be caused by natural magnetic disturbances in the Earth's crust (e.g., mineral deposits), affecting both electronic magnetometers and traditional magnetic compasses.
• Many experimental EFIS units and pilot training materials currently lack warnings or adequate education about these geological magnetic anomalies.
• Pilots should proactively research flight routes for potential magnetic disturbances, as traditional sectional charts may contain warnings not always highlighted on electronic displays.

Key takeaways sponsored by Aviator Pro | Start Your Training ->

See a mistake? Contact us.