Why must GPS be used as a backup for VFR navigation?

Using GPS as a backup for VFR (Visual Flight Rules) navigation is vital primarily due to the potential inaccuracies and errors associated with GPS technology. While GPS is generally reliable, it is susceptible to various factors that can impact its performance, such as atmospheric interference, signal multipath effects, and GPS satellite geometry. These issues can lead to degradation in position accuracy and reliability, making it essential for pilots to have alternative means of navigation, such as visual references or traditional navigation methods.

Additionally, during adverse weather conditions or in areas with limited visibility, reliance solely on GPS may not be sufficient. Having a solid understanding of VFR navigation principles and employing additional navigational aids provides an added layer of safety and ensures that pilots can maintain situational awareness even if GPS performance is compromised. This approach helps to mitigate risks and enhances overall flight safety.