Why is it crucial to check the FMS position before navigation?

Checking the FMS (Flight Management System) position before navigation is essential to confirm accurate navigation data. The FMS relies on various input sources, such as GPS, VOR, or ILS, to determine the aircraft's position and ensure that the navigation information it provides is correct. If there is any discrepancy in the FMS position, it could lead to navigational errors, potentially resulting in the aircraft deviating from its intended flight path.

Accurate navigation data is vital for all phases of flight, including departures, arrivals, and en route navigation. It helps pilots maintain situational awareness and allows them to execute planned maneuvers effectively. Confirming the FMS position ensures that pilots have the most up-to-date and accurate information available, which is critical for safe and efficient flight operations.

The other options may touch on valid points in different contexts, but they do not specifically address the primary reason for checking the FMS position before navigation as accurately as this answer does.