On Wednesday, January 6, 2016 at 7:36:27 AM UTC-8, Dan Marotta wrote:
In the spirit of technical discussion I must point out what seems to
me to be a basic flaw in logic.



The statement that you can gain or lose altitude at 10 m/s (~20 kt)
is certainly valid in the US southwest.* However the supposition
that two gliders traveling in opposite directions with 200 meter
vertical separation would be at risk of collision due to one
suddenly dropping and the other suddenly climbing in the same
airmass does not appear to be a serious risk.* To do
this would require one or both of the gliders to pull up in sink or
push over in lift.* In reality both would either pull up or push
over thus keeping the vertical separation nearly the same.



As to the stealth argument, if only ID and (claimed) climb rate are
masked, with position and relative altitude still displayed, where's
the loss in situational awareness?* Remember that there are still
right of way rules to follow to avoid swapping paint.



Someone mentioned the danger of one glider pushing over to leave a
thermal as another is pulling up into the same thermal.* This is a
valid concern, though a special case.* Assuming both aircraft are
equipped with some sort of anti-collision device then a maintained
situational awareness should preclude any abrupt maneuvers in close
proximity to another glider.* I realize that some folks have a "get
out of my way" philosophy and no device can be expected to keep them
from doing something unexpected.




On 1/5/2016 3:56 PM, Andrzej Kobus
wrote:



On Tuesday, January 5, 2016 at 9:02:51 AM UTC-5, wrote:


On Monday, January 4, 2016 at 6:08:40 PM UTC-5, Andrzej Kobus wrote:


I think it is time to end this back and forth ping pong about restricting the use of PF. We have to agree to disagree and try to come up with a solution that could work for both groups.
Let's try to define some criteria that might be acceptable to all:
1) Should targets be visible on PowerFlarm display?
2) If (1) is "Yes" then what is the desired distance at which targets should be visible on PowerFlarm display?
3) Do we allow for displaying altitude of another glider on PowerFlarm display?
4) Do we allow for displaying information pertaining to climb rate or simply indicate if a glider is ascending or descending?
5) Do we need to be able to identify a conflicting glider?
6) What are the minimum requirements for identification of conflicting traffic?
7) Should we aim not to degrade PF functions for non-contest participating PF users in the area of a contest?
8) How do we deal with ADS-B in a glider? I have ADS-B out plus I have ADS-B in on both 1090 and 978.
9) Anything else?




In the interest of having a constructive discussion on the topic- THANK YOU ANDRZEJ!, I will provide my personal opinions.
1- Yes
2- I have suggested 5km previously
3- Relative altitude only, with limit of 200meters(admittedly somewhat arbitrary)
4 No
5- Yes if it is an identified conflict.
6- Provide whatever ID the other glider is using. With ID's suppressed for tactical purposes, I think more pilots would be likely to make them available for conflict resolution.
7- Yes. To me this is the greatest shortcoming of existing Stealth. This is a double sided problem to solve. Plus- it provides little if any degradation of safety for other stake holders. This factor was the principle reason why the BGA stopped the Stealth mandate over there. Negative- it is much harder to ensure that the new mode performs equally for all without hackers turning it wide open again. This would require use of flight displays running programs shown to be compliant. Nothing is without complication. The other negative is that it could enable ground tracking . Possibly the privacy settings could prevent this.
8- I don't have enough visibility into how effective ADSB information will be tactically compared to Flarm to have an opinion. From a tactical point of view, I'd love it to be not there at all. From a safety point of view, I'd like it to be effective.
Again- Thanks for fostering a constructive exchange.
UH


I think we can find a common ground on a number of points:
(1), (2), (4), (5), (6), (7)
In regards to (3) I would suggest we increase the 200 meters and this is why. Flying in Ely, NV I learned that I can gain or lose 200 meters is just 20 seconds flying straight. I almost busted class A once.
Let's consider this closely:
We have two gliders flying in opposite directions. One glider gains altitude the other loses altitude. The other glider may all of the sudden appear on your display say 1 km in front of you with 200 meters of vertical separation (very difficult to see). You would be left with just 10 seconds to avoid collision.

The 5 km of horizontal distance gives us about 37 seconds of warning. We need to come up with the same 37 seconds of warnings for vertical separation.