On Friday, November 27, 2015 at 11:15:40 AM UTC-8, Martin Gregorie wrote:
On Fri, 27 Nov 2015 09:31:17 -0800, jfitch wrote:

James mentioned false alarms while diametrically opposed in thermals.
That is highly unlikely to be due to wind drift.

... which is something I've never experienced, but maybe I've never
shared a thermal with an idiot since I've had FLARM fitted. That said, at
my club there was one collision in a thermal between two FLARM-equipped
gliders. AFAICT from talking to the pilots, one of them was far from
being on the diametrically opposite side of the thermal and then misread
the intentions of the other pilot. Under these conditions FLARM won't
help because the time between its warning being triggered and the
collision is likely to be too short for either pilot to do anything about
it.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

The short warning you get in thermals is a limitation of Flarm. Mitigated by a very good tactical screen of which there are unfortunately few examples.. One of the compromises that appear to have been made to eliminate false alarms in thermals is a very short warning distance. I have flown close to other gliders in thermals (yes they were aware) to see just when the alarms occur. I'm not criticizing Flarm for this, something I think they had to do.. Too many extraneous alarms is as bad as no alarms at all.

On a good tactical screen (the original Winpilot remains the very best by a wide margin) gives you a 3D map of all the gliders in the thermal near your altitude. Very easy at a glance to see where everyone is. I do not know of another display with this capability but I found it very informative. Unfortunately the original Winpilot doesn't work with modern equipment anymore, so the facility has been lost.