Hi Tim,
Since talking to you back at the Flying Show, I have been doing some 'Mode S' testing for Lee Moore for PilotAware, to help establish the display of 'bearingless' contacts based on range, interpolated from signal strength (based on 6 years experience of using ZAON MRX and direct comparison with my MRX unit).

Back on 14th January, mode 'S' contacts from PilotAware showed on Sky Demon as a small aircraft 'piggybacked' on top of my own aircraft, coloured green, amber or red, dependent on received signal strength, giving an indication of the degree of risk, meaning low risk contacts could be given less attention, thus reducing distraction to external lookout. This I really liked, though the associated text for relative altitude was too small to be read easily.

All my more recent tests, starting from 16th/17th January, however, bring up a piggybacked small WHITE aircraft symbol, giving no indication of the relative level of risk. I raised this with Lee, who is looking into the problem, but am now wondering whether it may be due to something you have changed in the recent Sky Demon update(s). I know Lee did increase the trigger levels sometime towards the end of January as his early software was producing alerts while aircraft were too far out, but this change was after I did the later January tests, so shouldn't have affected the SD display at that time. If this was a SkyDemon change, it is in my opinion a seriously retrograde step as it makes it much harder to interpret potential risk leading to far too much time directed inside the cockpit at a potentially critical time. I am aware from my discussions with Lee that he will probably contact you directly to discuss this issue, but would be interested to know whether there was any deliberate change to the way SkyDemon reports bearingless 'Mode S' contacts which is more likely to have caused this problem.
Regards

Peter R

I do not recall a change to our display of bearingless targets in recent times, however I don't think SkyDemon will warn about such targets. Our collision avoidance algorithm works only with targets where we know where they are. The display on the map, of a ring, should remain the same though.