Geoff Kidd wrote:
In trying to understand your explanation, and wanting to fully grasp
the way these things work, I looked again at the Flarm video on DG's
website http://www.dg-download.de/Videos/flarm-rennes.wmv.
In that case the display alarms initially at the 12.30/01.00 LED,
which is about where the other glider is, when the tracks of the 2
aircraft appear to be intersecting but when there also appears to be a
reasonable height separation ..... and it looks to me like there was not
a "risk of collision".
They were on a converging heading. The FLARM was essentially saying,
"Even though the separation is high, if you continue the way you
are at the moment you will probably hit each other."
Note that the alarm tone was different to what it was later on when
they were closer.
The pilot then bears away to starboard and turns back to port to fly
directly at or towards the other aircraft.
Obviously not directly at it, because they didn't hit each other.
Unless it's directly in front of you, flying directly at the position
another aircraft is in *right now* will cause you to miss it, because
by the time you reach that position the other aircraft won't be
there anymore.
They were on diverging headings during that phase of the demo, when
the alarm was silent. They were in close proximity to each other,
but there was no collision risk, so there was no alarm.
It looks to me that there is a greater risk of collision after he
turns back to port towards the other ship when it is visible in his
screen ........... yet the alarm doesn't sound again until he is
reasonably close.
Reasonably close *and converging*.
There is no mystery to this, Geoff. You can fly as close to another
glider as you want; but if you're not converging with it, FLARM won't
bother to sound an alert (it'll still indicate proximity on its visual
display, but it won't sound an alarm to indicate an imminent collision)
That's the right answer, isn't it? Nobody wants a "collision avoidance"
system which chirps continuously just because you happen to be sharing
a thermal with someone else, do they? What we really want is a collision
avoidance system which is silent when you're sharing a thermal with
someone else *unless you're about to hit each other*.
- mark
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I tried an internal modem, [EMAIL PROTECTED]
but it hurt when I walked. Mark Newton
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