Interesting Dr Jack! I have the Garmin 196 and have
that fuction, but I input the destination altitude
in the setup/vnav/arrival altitude box. The only drawback
is that you have to set it each time you change a waypoint
unless the altitude is the same. There fore I use it
as final glide ie I set it to my final destination
and leave it unless in eminent danger of landing out
then I set to that airport or field elevation +800'.


At 03:48 29 July 2007, Jack Glendening wrote:
I've just upgraded from a Garmin 12XL to a GPSmap60csx
GPS. That has
the added functionality of giving the current 'Glide
Ratio' and 'Glide
Ratio to Destination'. It seems most new Garmins have
this feature,
which is obviously useful for us but does require that
waypoint
elevations be specified. So I wrote a simple Perl
program to convert
an on-line Soaring Turnpoint Exchange CAI file data
into a wpx
waypoint file containing waypoint 'elevation' fields.
Since others
might have a similar need I've put it on-line at
http://www.drjack.info/MISC/SOAR/GPS/convert_cai2gpx.pl
though its use of Perl makes it useable only by a small
number of
pilots.

I've been able to read its output file with Garmin's
MapSource
software and use that to upload the waypoints to my
GPS, but use of
G7toWin also works. I've only used this with the CAI
file for my
local area and with my GPSmap60csx and so offer it
on a 'if it works
for you that's great' basis as I don't plan to worry
about other GPSes
or possibly anomalous CAI files.

For the waypoint elevation I used the airport elevation
plus 1000 ft
as a buffer (also putting the true field elevation
in the comment
field as a reminder) but others may want to use other
values. There
are some other caveats noted in the program - in particular,
I had
some difficulty specifying symbols which would appear
as other than
the default 'blue flag' so while airports appear with
an 'airport'
symbol the non-landable waypoints use a 'Glider Area'
symbol which in
older GPSs appears as a glider but in mine appears
as a
hangglider-like triangle.

Jack Glendening