Questions regarding the NADIR and POS FIX

[Home Fries]

I pretty much have the NADIR figured out (except for the utility of polar mode), but I can't figure out how to use POS FIX.

 

I assume POS FIX is a means to update your navigation solution with current coordinates to correct for drift. However, when I press it, I can't figure out what to do next, or how to exit from the mode.

 

That also begs the question whether drift is modeled in the Gazelle (since Doppler nav systems are not normally as accurate as inertials), and in particular if drift is exacerbated when flying over water in land mode or land in water mode. The next logical question is if drift is not modeled, is there a useful application for POS FIX?

 

Thanks. BTW, Gazelle has beaten out the mighty Huey as my favorite module.

Edited October 5, 2016 by Home Fries