Nielsen-Kellerman ClearNav - Manual (Page 42)

NK ClearNav Manual • Version 0.5 • July 3, 2008
Page 42 of 86
optimizing your glide angle. However, many more experienced glider pilots consider it to be less safe
than leaving the MacCready number at a setting that matches the actual soaring lift conditions. The
reason is that at a MacCready setting of zero you are at the ragged edge of making it home. You have
no margin for error (or sink). You can’t slow down any additional amount to stretch your glide or
speed up to get through sink. With the MacCready set to match the day’s soaring conditions the flight
computer will recommend that you have more altitude before starting your final glide which will allow
you to slow down to stretch your glide in the future if necessary or speed up in sink and still have
enough extra altitude to make it home. In addition, you will arrive home more quickly.
Total Energy Final Glide
The ClearNav uses a feature called “Total Energy Final Glide” to take airspeed into account when
calculating glide altitudes. When your speed increases the number in the Final Glide window will
decrease because less altitude is required to make it to your destination – because you can pull up and
gain some altitude at any time. When your speed decreases the number in the Final Glide window will
increase because more altitude is required to make it to your destination – because you have less extra
energy to convert into altitude.