John
Assuming you completed all the information in you Aircraft Profile section including your glide ratio, all you have to do when flying and you have a problem is touch NEAREST.
All the nearest airports close to your flight position will show in a box at the top of the screen on a phone or tablet.
In the top right corner of the box you will see a red triangle with an exclaimation mark in it.
Touch on that mark and the little boxes next to the airport identifier will turn to either red, yellow or green.
If red you won't make it to that field. If yellow you MIGHT make it to the field. If green you SHOULD make it safely.
Of course, your results may vary depending on:
How quickly you respond to turning to the field
How well you maintain optimum glide speed for YOUR aircraft
And of course, any winds that may hinder progression over the ground.
Sometimes you will have a choice of more than one airport.
I have a continual indication on my Dynon 10A as to the winds aloft so I may choose an airport a bit farther in order to benefit from favorable winds.
The other feature of Nearest is that no matter what course you are following it will lay out a course line to the optimum airport for you.
Neat huh?
John M