Michael Zupanic introduced OzGAP 2005 in September of 2005.

http://www.hgfa.asn.au/Competition/downloads/OzGap2005.htm

Place based Arrival Points are gone. OzGap 2005 is simply a time
based Arrival Points system that constitutes ¼ of the available speed points,
that means that if the maximum Distance Points available is 600 points, 300 will
be available to speed and 100 points will be available for arrival points.

If you use the OzGAP 2005 scoring system in FsComp, the official
hang gliding and paragliding scoring program from CIVL, which uses Arrival Time
Points and no Leading Points, you'll get the results that Michael intended. But
starting with the FS2025 R4 version of FsComp, if you use Arrival Time Points
and Leading Points (an option in FsComp) the Arrival Points available are cut in
half, equal to the available Arrival Position Points in GAP 2000.

We recently found this out because Mitch Shipley looked into the matter. He
wrote:

Using Arrival Time points vs Arrival Position points in FS. I know
checking that block in FS in Mexico 2015 on the practice day resulted in 200+
points being allotted to Leading/Arrival. Since then I thought it had not been
fixed. I just re-ran a task from Brazil using arrival time points and it looked
fine, both with Gap 2016 and several earlier versions of GAP. I’m checking with
FS guys to see if they did something with FS that fixed the problem because it
doesn’t seem to have been caused by the Gap version. Can you check with one of
your comps as well to see if it works now?

Joerg Ewald wrote back

Previously, whenever you chose arrival time points, the arrival
weight was (1 – distance_weight) / 4. This was the “too much” you observed in
Mexico.

Now, this is only the case if you don’t use leading points as well.

If you do use leading points, the arrival weight is (1 – distance_weight) / 8,
the same as for arrival position points.

This correction came with FS2015 R4.

Numerous times scorekeepers attempted to replace Arrival Position
Points with Arrival Time Points without being aware of the fact that they did
not provide an equivalent number of points. They just assumed that there were
two different ways of calculating the distribution of the same number of Arrival
Points. There was no obvious warning in FsComp that this was the case.

It appears that we were not told of the change that Joerg made at the time that
he made it, at least I can't find any record of his informing us. Paraglider
pilots use only one start time so they don't need to be concerned about these
particular issues (although the issue of how leading points are calculated is a
big concern for them).

We were looking at scoring issues at the time:

http://ozreport.com/19.116#2

http://ozreport.com/19.118#0

The results of all this is that if you as a hang gliding competition scorekeeper
wish to use Arrival Time Points and Leading Points instead of Arrival Position
Points and Leading Points, you are free to do so without over counting Arrival
Points.

Update:

Joerg writes:

Arrival time points were introduced before my time when OzGap was
added to FS. At that time, nobody had thought that they would ever be used in
combination with Leading Points, so nobody realized that they were overvalued in
that case. When people started substituting arrival position points with arrival
time points in “regular” GAP, this became obvious, and I was asked to correct
it. I do not remember by whom, may well have been Mitch after his experiments in
Valle. So I created the corresponding ticket in Trac:

http://fs.fai.org/trac/ticket/337

After fixing it, the fact that it was fixed was logged the usual way:

http://fs.fai.org/trac/wiki/FS2015R4

I was the one that wrote to Joerg. I just don't have any record of
specifically hearing back from him. I don't go checking the ticket logs that
frequently: I wrote:

From: Davis Straub


Sent: Monday, September 21, 2015 9:20 AM

To: Joerg Ewald

Cc: Jamie Shelden ; Jonny Durand ; Mitchell
Shipley

Subject: Arrival time points in FS.

Hi Joerg,

As you well know the Arrival Time Points
check box presents a problem as scorekeepers
in the past have assumed that they could
just uncheck Arrival Position Points and
check this box. Jamie, Mitch, and (as I
vaguely recall) Jonny hoped to be able to do
that once again at the 2015 Santa Cruz Flats
Race. I had to point out that this was not a
good idea.

The points apportioned for Arrival Time
Points (which are calculated using the
formula from OzGAP 2005) are equal to the
total of the points apportioned to the
combination of Leading Points and Arrival
Position Points. Therefore combining Leading
Points and Arrival Time Points reduces the
points that would be given to time (speed)
points.

What is trying to be accomplished is to just
replace Arrival Position Points with Arrival
Time Points without reducing the points
given to time points.

This can be accomplished by a minor change
in the underlying code. In addition a change
should be made in the user interface to make
sure that scorekeepers who wish to do this
and use leading points also should be able
to do so without reducing time points.

I hope that I have been clear here without
also including the formulas.