Steve Kroop at Flytec <<info>>
writes:

A few years back I was discussing final glide on the 6030 with
Daniel Velez. The 6030 will tell you the ideal speed-to-fly for final glide
based on the strength of your last climb assuming that you climb in that last
thermal to Alt a WP = 0 and that lift/sink on the glide net zero. Daniel's point
was what happens if you get a particularly good or bad glide on final, what
speed should you fly? For example, if in your last thermal you climb to Alt a WP
= 0 and your average climb rate was 600 ft/min (3m/s) you would go out on final
glide with a speed ring setting of 600 ft/min (3m/s). However, if you fly
through a long period of sink you will likely have to slow down because you will
no longer be able to make goal at that speed ring setting. Daniel's point was,
what is the new speed ring setting?

There is another situation where there would be some question as to the correct
speed ring setting on final glide and that is if you are unable to climb to Alt
a WP = 0 in the last thermal (e.g., the thermal tops-out or there is some form
of altitude restriction). In this case, when you go on final, you cannot fly a
speed ring setting equivalent to your last climb because you did not acquire
sufficient altitude. Again what speed do you fly?

The answer to both of these situations is found by using two straight forward
but very helpful user-fields L/D gnd and L/D req. When on glide, if you control
your speed so L/D gnd = L/D req (your actual current glide ratio over the ground
and the glide ratio required to make it to the waypoint) then you are flying the
correct speed to arrive at goal at 0' AGL and the McCready pointer (radial line
in the vario dial) will be indicating the corresponding speed ring setting.

The McCready pointer reflects the best speed ring setting from your current
position to goal - well at least until the situation changes again. Some caution
here, flying the speed where L/D gnd = L/D req is generally not advisable unless
it is abundantly clear that conditions on course line are becoming more
favorable. It is prudent to back off of the speed ring setting determined by L/D
gnd = L/D req. By how much depends on what conditions look like on the way to
goal, feedback from pilots in front of you, your gut, your horoscope, etc. It is
also important to note that reassessing your final glide speed ring setting
should not be done actively or you will end up flying reverse speed-to-fly
(slowing down in sink). Remember, speed-to-fly assumes lift and sink will net
zero, not that there will be no sink on your glide. Reassessing should be done
after a significant period of excessive sink.