The Time - Distance scoring system has been used for the last three Canadian
Nationals. It has been well accepted by the majority of the competing
pilots. So far, we have still normalized the score to 1000 points, in order
to make the TDT compatible with traditional scoring systems for Assigned
Speed Tasks and Pilot Selected Tasks which are still part of the Canadian
Nationals Rules. However, we are now comfortable enough with TDT to
seriously consider to eliminate the 1000 point system altogether and express
the score in kilometers instead of points.

Here are the main reasons why we went to a scoring system where speed is
expressed in distance over a set time TDT:

1. Fairness
The pilot's score depends exclusively on his distance achieved and is not
influenced by the scores of other pilots. The scoring bias in favour of
gaggles (see Bruno Gantenbrink's lone wolf article) of traditional scoring
systems is eliminated.

2. Logic
Traditional scoring systems attempt to score two dimensions: Speed and
Distance. The ratio of speed to distance points is arbitrary and depends on
the ratio of pilots who complete the task to those who land out.

3. Simple scoring
Since the score is based on distance every contestant knows where s/he
stands as soon as the distance is totaled up.

4. Suitable for Assigned Tasks as well as Pilot Selected Tasks and AAT
Obviously an Assigned Task must be open ended to avoid that competitors run
out of task before their time is up. Such a task could be set as a triangle
that brings the competitors back to the contest site after about 80% of the
estimated achievable distance. A smaller triangle (approx. 40% of achievable
distance) can be added with multiple laps to ensure even a very fast
competitor will not run out of task.
In practice most contestants will "time-out" near the competition site. The
slower ones will be on the last leg of the first triangle, while fast pilots
will be somewhere in the smaller triangle.

The traditional scoring systems need different scoring formulas for
assigned, pilot selected or area tasks.

5. Classic task setting problems eliminated
The margins for error are significantly greater since the major decision is
on the task time (i.e. 2, 3 or 4 hrs) and the distance is only secondary.
Even if the task setter gets it somewhat wrong, it may still be a great day.

6. Ideal for handicapping
The traditional Assigned Speed Task is problematic when handicaps vary
widely. In such a scenario it is quite possible that high performance ships
burn around the course in less than two hours, de-rating the day, while
lower performance ships cannot complete the course. Since the best handicap
factor cannot compensate for the loss of speed points, the low performance
ships have no chance. An assigned TDT can be set in such a way that
everybody has a good chance to make it home and even if he doesn't he still
gets a reasonable score.

Is it a race?
Of course, the pilot who goes the furthest in a given time is also the
fastest.


And what do you do about landouts? How do you avoid the incentive to
dive to 100 feet as time ends?

Landouts are scored in the same dimension as finishers -- distance. It has
not been our experience that people drive it down to the deck at timeout.
This strategy may win one day if one is lucky enough to get back up and make
it home but over several contest days the loss of the home bonus would
outweigh the benefits.

We just had a long thread about this involving both theory and
experience from the Canadian nationals, the conclusion of which was
pretty much that handling landouts is an usolved problem

In our experience landouts have not been a problem at all. Actually, we have
seen fewer landouts on assigned time distance tasks than on assigned speed
tasks. The distance of an assigned speed task should be such that it makes
good use of the day's expected conditions. If the day doesn't turn out as
expected a number or all of the contestants will not be able to finish the
task and land out. We have never had a mass landout under TDT scoring --
assigned or pilot selected.

There is little incentive for "make it or break" it final glides because
landing on the wrong side of the fence doesn't eliminate you from the race.
Therefore final glides in the "coffin corner" have not been a problem.

Nobody seems happy with the kind
of flying that total distance requires.

As I said before, the majority of competitors who have flown the last three
Canadian Nationals are quite happy with this scoring system.

There are various possibilities to eliminate the incentive to be low on
time-out. Such as incorporating the time out altitude in the score.

Joerg Stieber

Sporting Committee
Soaring Association of Canada

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