On Friday, August 7, 2015 at 10:49:31 PM UTC-4, John Cochrane wrote:
So we should impose stealth mode now because somebody might some day write some killer software that might let people know where thermals are and this might turn out to be a bad thing? I've "written specs" for lots of stuff too, like thermal detectors. No reality yet.

I think we need to get back to a simple principle: Let's see if something is really a problem before we start passing rules against it.

Surely, you guys who want to impose stealth mode can come up with some real, serious, documented problem that real flarms today are causing, not just hypothetical problems of hypothetical future software?

By then we'll all have FAA mandated ADSB displays of all traffic, super cheap drone anti-collision technology showing us where the thermaling birds are, and so on.

John Cochrane

I'll provide here a portion of a report written by one of the major rules thinkers without attribution as I do not have his OK to do so.
What's the problem
Range of Flarm now gives competitors the opportunity of identifying, locating and assessing the climb rate of competitors over 20km away. This has evolved with the production of better Flarm electronics (Powerflarm) and a better understanding of influence and importance of antenna location and design. Whilst the improved performance is most welcome as it now ensures that all installations are seeing and being seen at the important 2km range with much reduced blind spots(2km required for effective collision avoidance head to head), it has dramatically increased the tactical use by competition pilots.
Tactical benefits on task include being able to assess climb rate of others and identify where important pilots are in order to make improved strategic decisions. Even if the targets in view are not "tagged" they give important information for gliders behind to optimise routing and to ensure that if required a follower may ensure they fly the same route. Tactical benefit prior to start is even greater as it allows a full view of the start line area so it is clear where all the start gaggles are located, where key competitors are, whether they have started and sometimes what rate of climb is achieved in the first thermal on task.
It is arguable whether this sort of tactical assistance diminishes the art of racing gliders. I believe it does but this is not the main thrust of this paper. Flarm in isolation is a great safety device that has rightly been encouraged to the position we find ourselves today where it is mandatory in all FAI Cat 1 events. However, it is now very clear from feedback from International competition pilots that the workload in gleaning the "necessary" tactical data from the Flarm device is diminishing or eliminating the apparent added safety that the underlying Flarm provides.
What are pilots doing:-
1 Spending way too much time scanning moving maps for tactical contact detail instead of look out
2 Spending way too much time "tagging" competitors instead of look out to improve tactical content
3 Turning their Flarm units on and off at will to avoid tactical benefit accruing to others
4 Blanking antennas to reduce or eliminate range to avoid tactical benefit accruing to others
5 Installing amplifiers to increase range even further
6 Utilising two port Flarm units with one send/receive and one receive only antenna to maximise the range received but eliminate or restrict transmit range.
7 Changing backwards and forwards from "stealth" to full ON mode to minimize tactical benefit accruing to others but maximising own benefit as required.
Whats the effect
1 Safety is significantly diminished due to significant head in cockpit time inputting and viewing the Flarm for maximum tactical benefit.
2 Following or "leaching" is much easier so the eternal problem of gaggling is further encouraged at the possible cost of safety.
3 It is much easier for pilots of lower skill level to fly at the same XC speed as the best pilots.
What's the solution

Please read and consider with an open mind.
UH