(Ramy Yanetz) wrote in message

These devices should be capable to tell you if you are in a collision
course, not just warn you of a nearby aircraft. Earlier someone posted
a link to a new device which also calculate collision course while
thermaling! If you thermal too close to someone else it should warn
you.


But how close is *too close*? I am perfectly comfortable cranked up
at a 50 deg bank with someone opposite me doing the same thing, but
very uncomfortable if another glider joins with the same separation
and puts me in their blind spot.

To be effective in providing warnings the device would have to
continuously predict collisions based not only on the current
trajectory of each aircraft, but also predict collisions based on all
possible future trajectories for the next say 30 seconds. Try
resolving that mess when there are 30+ gliders at the top of the same
thermal waiting for a contest start. The false alarm rate would be
unacceptable.

The nearest the US regulators have come to such a system is the
proposed ADS-B, but that seems to be a long way from the dream of 10
years ago that a GPS based ADS-B could be small and cheap enough to
be carried by ultralights and skydivers.

Andy (GY)