Article on glide strategy

On Mar 8, 9:55*am, Mike the Strike wrote:
Still important, but perhaps for a separate thread, is a strategy for escaping from a line of sink rather than just dealing with the mathematical consequences.

As I noted earlier, lift and sink lines are frequently aligned and knowledge of the relative heading of the glider along or across these lines would give the pilot useful information for an avoidance strategy.

You can see the forecast predictions of any such lift/sink lines on the RASP Boundary Layer Up/Down Motion or the equivalent HRRR field "Mean Layer Vertical Velocity".

Changing your final glide heading from a line of sink into a line of lift might have more benefit than accepting the inevitable and dialing up doom on your flight computer!

Mike

Yes. In rivers of blue sink, I often just head 90 degrees off course
and wait.

Put another way, though, you have to use a much higher glide slope
(MacCready value + reserve) for safety spots that are upwind/downwind
or aligned with lift/sink streets than for safety spots that are
crosswind or not so aligned. The airports are where they are, so going
crosswind isn't always an option.

John Cochrane

Great article, John, and another valuable service (as usual)! I like
to think it analyzes and explains what many pilots have been doing
somewhat intuitively (based on experience) but I suspect we all have
our own style.

Often I will leave the MC set as speed to fly but keep climbing in
what may be the last thermal. If the climb rate is above MC, I just
keep climbing, of course. As the thermal weakens and they converge and
I'm now above glide path, I bump the MC setting up enough to push the
final glide margin down to zero (though I've still got my 300 or 500
goal margin set) to see how "fat" I am. I'm frequently surprised at
how quickly the MC settings increase to what seem to be absurd levels
in the East, which is another way of saying that using very high MC
settings doesn't give you nearly the unassailable safety margin (in
feet) you might think. I usually don't fly that absurdly high MC
setting until I'm fairly close in (and/or over landable terrain or
with good clouds and/or markers ahead to pick up a little extra). In
fact, I'll switch back and forth and to see what the MC setting is
that would take me all the way home and whether it's increasing or
decreasing vs. what is my margin over final glide at cruise MC and
whether that's increasing or decreasing. No wonder final glides are so
confusing.

This argues for decoupling final glide MC from speed to fly MC, as you
suggest.

Chip Bearden
ASW 24 "JB"
U.S.A.