Do barometric altimeters perform better than GPS in fog?

Precision in Adverse Conditions

Barometric altimeters rely on the principle that atmospheric pressure decreases with increasing altitude. They use a sensor to measure this pressure and calculate the altitude. In foggy conditions, GPS signals are often disrupted, but barometric altimeters can continue to provide precise altitude readings. A study found that a barometric altimeter provided accurate readings to within 10 feet (3 meters) in foggy conditions, while GPS signals were lost.

Limitations of GPS in Fog

GPS signals rely on line-of-sight transmission between satellites and receivers. In dense fog, the signal is often blocked or severely attenuated, making it difficult to obtain accurate location and altitude information. In contrast, barometric altimeters do not rely on satellite signals and can continue to operate even when GPS signals are lost. This makes them a more reliable choice for navigation in foggy conditions.

Practical Considerations for Choosing an Altimeter

When selecting an altimeter for use in foggy conditions, it’s essential to consider the type of altimeter and its sensor quality. Mechanical altimeters and some electronic altimeters can be prone to calibration errors, whereas high-quality digital altimeters with accurate pressure sensors are more reliable. In addition, it’s crucial to calibrate the altimeter before use and to understand its limitations in extreme weather conditions.