The Navitron NT851 NFU is a non-tracking control lever. This unit is activated immediately when the steering selector-switch mode is set to the NFU. Lever activity is indicated by a status LED on the control panel.

The Navitron NT851 NFU behaves in the same way as the NT850 NFU, but this non-tracking lever model does not have a SYNC button and is therefore more suitable for use as part of single-rudder systems or dual-rudder systems that are permanently connected (e.g. do not support separate use).