PowerFLARM leeching comments

On Sunday, October 21, 2012 9:52:17 PM UTC-4, wrote:
On Sunday, October 21, 2012 6:41:11 PM UTC-5, Evan Ludeman wrote:

On Oct 21, 7:35*pm, wrote:



On Saturday, October 20, 2012 5:52:55 PM UTC-4, Dave Nadler wrote:



On Saturday, October 20, 2012 5:30:05 PM UTC-4, Don Johnstone wrote:







... I was very uncomfortable with the concept of instructing







pilots to lessen the efficiency of an anti-colision assistance device.







Stealth mode in no way lessens the efficacy of FLARM anti-collision..







It gives you warnings when there is a collision hazard regardless.







Hope that is clear,







Best Regards, Dave







Dave,







it is clear, and while your statement is probably technically accurate, it isn't entirely correct. *Any mode that reduces the pilot's situational awareness also degrades safety to some extent. Stealth mode by definition does exactly that. *The OC fatality scenario is a case where stealth mode might not provide enough warning to assess the situation and take appropriate action, whereas the 'full' mode probably would. *Just my $0.02







Frank (TA)







See pg 19 of the PowerFlarm Dataport Specification for details about



how stealth mode works.







It's he http://tinyurl.com/8ne9cjx







Stealth mode does not change the anti-collision functionality of



PowerFlarm at all. You'll get the get the same 25 seconds warning,



which is plenty.







Evan Ludeman / T8



"Plenty" is interesting. Let's all remember, flarm is not a "collision avoidance" device. It is a "collision warning" device. You still have to find the other glider, avoid it, and not run in to anyone else while you're doing that. Don't just bank away from the collision threat, make sure there isn't a new collision threat.



If glider A is a collision threat, glider B is off to your side and not a collision threat, will flarm show glider B in stealth mode? No, I gather. If you suddenly bank towards glider B to avoid glider A...



And it doesn't always give 25 seconds warning, especially if carbon fuselages are blocking signals. Gliders have collided when both had operating flarm systems. Norway and Uvalde.



A stealth mode is far from obviously a good idea, if it only shows imminent collision threats. The operation and reliability of such a mode have to be really bulletproof. Which, given power flarm's recent history with range issues, software updates, antenna updates etc., would seem to be something one would want a lot of real world experience with. But how do we get real world experience and find out its actual limitations?



It's interesting how many reports we're getting of pilots who saw collision threats with flarm. But we obviously don't know about the failures until they hit each other. And how do we learn about the failures under stealth mode. Can of worms here.





John Cochrane

If there's a comm problem between flarm transceivers, then the operating mode simply doesn't matter. One advantage of the open mode is that it provides a means to test the system performance without aerial jousting. And yeah, I see a lot of carbon gliders (V2's mainly) with really spotty contact.

Short warning time when comm is established probably reflects maneuvering, i.e. a course conflict that arose "unexpectedly". For high speed head on traffic, "maneuvering" doesn't necessarily mean much. A small heading/glide slope change is all it would take.

T8