How can atmospheric pressure lead to navigation errors?

Atmospheric pressure plays a significant role in navigation, particularly concerning altitude readings. When atmospheric pressure varies, it directly impacts the accuracy of altimeters, which are calibrated to measure altitude based on a standard atmospheric pressure of 29.92 inches of mercury (Hg) at sea level. If an aircraft is flying in an area where the atmospheric pressure is lower than standard, the altimeter may read a higher altitude than the aircraft's actual position above ground level. Conversely, if the pressure is higher, the altimeter could indicate a lower altitude than reality.

This discrepancy can result in significant navigation errors, especially during critical phases of flight such as takeoff, landing, or flying at low altitudes. An incorrect altitude reading due to uncorrected pressure changes could lead to flying too high or too low, possibly resulting in hazardous situations such as insufficient terrain clearance. Properly adjusting altimeter settings to the current local atmospheric pressure is crucial for maintaining accurate altitude readings and ensuring safe navigation.