We get a resolution of what point is used for the
calculation

Back on September 16th, 2019 right after the 2019 Santa Cruz Flats
Race I wrote to Joerg Ewald, the person most likely to understand my question
about the Flytec 6030. I wanted to understand how the 6030 was calculating my
required L/D, or glide ratio, to goal. Here is an edited version of that email
to Joerg.

Steve Kroop, Flytec USA, said I should contact you about these questions and
I'll share the answers with Oz Report readers.

On Sunday at the Santa Cruz Flats Race in Casa Grande, Arizona the task
committee called a task with a 13 kilometer goal cylinder. The idea was to make
it safer to land on the east side of the Francisco Grande hotel. There were a
lot of easier ways to make this happen, but that's what we were stuck with.

I set up the task on my Flytec 6030 and Volirium P1. On the P1 I didn't notice
that the goal was defaulted to a goal line and not a cylinder so I made a 13 km
goal line not a 13 km radius goal cylinder. I have learned from that experience.
The P1 always optimizes so I had assumed that it would optimize to the edge of
the goal cylinder.

I didn't optimize the task on the Flytec 6030. Because of the way the task was
set up the difference between going to the optimized points and heading toward
the center of the turnpoints was very small. Besides because the P1 optimized
automatically I would have that information also.

After I made the second (and last) turnpoint, both instruments said I had 30.9
km to goal. I could see that it was only about 17 kilometers to the edge of the
goal cylinder. I was climbing and wondering just what to make of what I saw on
my instruments.

I went on what I felt was a good final glide when others took off for the goal.
While on glide I noticed that "A BG Goal"  (altitude above best glide line
to goal) was minus 1,000'. My "Alt a WP" (altitude that I would arrive at at
goal - the next waypoint) was plus 1,000'. My "L/D Goal" (required glide ratio
to get to goal) was 48. 

I assumed that "A BG Goal" was using the waypoint at the center of the 13 km
radius goal cylinder to display the altitude I was below the best glide line to
the center waypoint not to the edge of the cylinder.

I assumed that the "L/D Goal" was also using the same waypoint at the center.

I assumed that the "Alt a WP" was using a point on the edge of the goal
cylinder.

Was I correct in those assumptions?

Would the values displayed have been different if I had set the task as
optimized, i.e. would they have all used an optimized point on the edge of the
goal cylinder?

I was able to make goal just gliding into goal. I arrived at the edge of the
goal cylinder at about 1000'.

https://ozreport.com/23.185#3

On March 1st I got an answer from Joerg about this (we had a number of emails
back and forth in September). Joerg wrote:

Sorry this took so long. No idea if this is still relevant, but in
answer to Davis’ assumption (“I assumed that the "Alt a WP" was using a point on
the edge of the goal cylinder.“):

You are correct! Looking at the 6030 code, it seems that the distance value used
to calculate “Alt a WP” is “distance to cylinder”, regardless of whether you use
optimization or not. Which makes somewhat sense.

It also seems that without optimization, the remaining distance to goal is
calculated wrong, to the center of the last cylinder. But only until you took
the last turnpoint before goal. So you would have seen the 30.9 km distance to
goal right before you took the last turnpoint, and then maybe for 1, 2 seconds
longer, until the new calculation came into play, which correctly calculates to
the cylinder edge.

And that distance to goal is used to calculate “A BG Goal”.

On the P1, the 30.9 km make sense, since it was calculating the distance to the
center of the goal line you entered. On the P1, we also do not try to estimate
(or guess) your future glides nor the wind impact on your glide (as the 6030
does), and therefore don’t give such values. We give required glide to goal,
which is always correct, and lets the super computer between your ears do the
evaluation of whether your altitude is sufficient to reach goal or not. This
reduces pilots’ frustration considerably, we found.

I don't recall the distance calculation going toward goal changing
at all after I made the turnpoint. I was climbing after the last turnpoint and
that is where I was checking these values because I wanted to know when to stop
climbing and go on final glide.

Joerg responded (slightly edited) to this last paragraph:

Interesting. I admittedly do not fully understand everything that
is going on in the code, but it does look as if, once you’re on the final leg,
it would only use the distance to the cylinder edge.

At any rate, I am considering correcting this in the code now, so that:

If you use optimized, everything is calculated for the cylinder edges.

If you use non-optimized, everything is calculated for the cylinder centres,
including goal cylinder.