Hi All,

I'm working on a project that I can't talk about much, but I was
hoping to prevail upon some experts here. I need to analyze some IGC
files in my project, and try to use the data to determine the behavior
of the glider.

As I understand it, the bulk of the IGC file is just a series of time-
stamped position & altitude fixes. So to determine an aircraft's
heading (ground-track to be more precise, since we're referencing GPS
coordinates), I have to use pairs of position-fixes to come up with a
direction & velocity vector... Yes?

OK, now here's where it gets a little tricky: How to I make the leap
from those raw vectors to determining behavior? For example, you can
signal your release from tow by executing a sharp 360-degree turn.
Its easy enough to look at a few vectors in a row and as long as they
keep angling off to the same side (relative to the previous vector)
then I can consider the glider in a continuous turn. As long as the
continuous turn takes us past 360 degrees from the ground-track/
heading at the beginning of the turn, we're OK - right? But what
happens if the glider catches a gust of wind that slews the tail
momentarily or causes the glider to slip? What is my "fudge factor"
for these things and how do I reasonably account for them?

There are some other oddities that I'm unsure how to account for (or
if I even need to) - like: How do I deal with a wind-drift that's
causing the glider's absolute position to be offset?

I'm a programmer & IT person by day, but my work is keeping me
terribly busy and I've never had to do much in terms of pathing or
vector analysis - so this stuff is harder for me than it should be
right now. :-P Any help would be much appreciated!

Thanks, take care,

--Noel