At what latitude is FMS navigation prohibited?

FMS navigation is prohibited north of 73 degrees north latitude and south of 60 degrees south latitude. This is primarily due to the environmental conditions and operational limitations present in these extreme latitudes which significantly affect the accuracy and availability of satellite navigation systems used in FMS (Flight Management Systems). In the high polar regions, the geometry of satellite constellations can lead to reduced accuracy, and the reliability of the signals can be compromised. Additionally, the associated challenges in maintaining standard flight operations in these areas contribute to the prohibition of FMS navigation.

The other choices suggest different latitudinal limits that either extend too far north or south, which do not align with the established operational guidelines and safety protocols related to FMS navigation.