On Oct 28, 2:14*pm, Eric Greenwell wrote:
This projected path is a key element to the system working properly.
Without it, each FLARM unit would have to calculate the path of every
nearby glider; with it, each unit only has to calculate one path - it's
own. Potentially, it could be using a much higher position rate than
once a second to calculate it's projected path. In any case, the result
is much better than you might think for a system that transmits once a
second.

...
You may be underestimating the value of transmitting the projected path.
When another glider is first detected, your unit has only one position
report and can not determine the flight path from that single point, and
it will take several more precious seconds to determine the flight path
of the potential threat; however, because the projected path is
transmitted every second, your unit immediately knows it.

It would be interesting to get more detailed information on the exact
algorithms that FLARM uses in it's collision threat analysis and
compare this to the actual unit performance in situations where
gliders are flying at close distances in formation or in gaggles. *
This could also help pilots understand the limitations of these
systems so they don't develop a false sense of security in situations
where these systems are not reliable.

I'm sure the developers have tested their algorithms with thousands of
simulations using IGC files from gliders in many situations. The Parowan
accident simulation at

http://www.gliderpilot.org/Flarm-Par...dairSimulation

shows what can be done. It would be interesting, informative, and
entertaining if there was a website or application that would let us run
IGC files we select in a simulation like this. I'm curious about how
Flarm would react in a few situations I've encountered. Doing
simulations on a pilot's own files might be more persuasive of the value
of Flarm than even the most well-written explanations, and much more
easily understood than the algorithms themselves.

If you watch the Parowan simulation carefully, you will see that
the collision alarm sounds BEFORE the straight-line trajectories
intersect. This is because one of the gliders is circling, and the
projected trajectory (circling) shows a collision SECONDS
before the straight-line trajectories intersect.

These additional seconds can be a life-saver.

Hope that helps clarify,
Best Regards, Dave "YO electric"