All this talk about speed and distance. Why not combine the two and
think in terms of time?

With a first warning at, say, 15 seconds, make a gentle turn according
to the right of way rules. What could be simpler? Why would you need
anything more complex? The algorithm will compute tracks and issue
warnings. Look outside, make a gentle turn, and enjoy the flight.
Talking about "crossed wings" clouds the issue under discussion. If you
make a small course correction at the initial collision warning, getting
that close won't happen. That's more of a thermalling thing, not a near
head-on approach. Worrying about someone getting a bit of a lead in a
contest at the risk of getting run over is, in a word, stupid.

Full disclosu I do not use Flarm, but that's not to say that it's
not on my list of future upgrades.

On 11/27/2015 9:41 PM, wrote:
My math is correct, my typing was not: 1/4 of a minute warning! That is actually not much time to be alerted, accept the alert, come up with a plan of action and react. This is why it is better to have Flarm set you can see the gliders coming your way, while there is enough to plan not just react. Western flying at speed and altitude under mountain generated clouds streets is different than eastern flying, and requires its own set of safety parameters and flying style. Not every peg fits in every hole.


On Friday, November 27, 2015 at 12:49:53 PM UTC-8, wrote:
"The $PFLAA sentence is info about proximate aircraft displayed on your device. In stealth mode this info limited to aircraft within 2 km and +/- 300 meters vertically. Stealth or competition mode also removes ID, climb rate, track and speed from the display output for these proximate aircraft. It continues to use these variables to calculate the collision avoidance algorithm in $PFLAU."

Imagine two gliders flying in Utah at the nationals at 17,000 feet 100 knots indicated under cloud street on opposite courses. Say the 100 knots indicated is 134 knots true. Closure rate 268 knots or 496 kph, covering 2Km is about 1/4 a second warning. Just saying.



On Friday, November 27, 2015 at 11:57:18 AM UTC-8, XC wrote:
I am still seeing a lot of misinformation out there. I have two points to make supporting the use FLARM stealth mode in contests.

1) Stealth mode still allows the display and audio warning for threat aircraft no matter what the range.

and

2) FLARM used without stealth mode leads to an invalid score sheet. This is more true in eastern U.S. or European contests with lower working bands and more potential landouts.


First, I'd like folks to understand that FLARM sends two different messages to the display devices.

The $PFLAU sentence has priority and contains info about intruder alerts and obstacles. The contest ID is removed in stealth mode. Alerts are unaffected no matter the range. It really works quite well with the algorithm the FLARM people have developed.

The $PFLAA sentence is info about proximate aircraft displayed on your device. In stealth mode this info limited to aircraft within 2 km and +/- 300 meters vertically. Stealth or competition mode also removes ID, climb rate, track and speed from the display output for these proximate aircraft. It continues to use these variables to calculate the collision avoidance algorithm in $PFLAU.

Folks should read FLARM release notes for FLARM 6.02 Firmware, FLARM data port specification TFD-12 and FTD-14 FLARM Configuration Specification for full understanding. Anyway, we found in Elmira last year it worked quite well and the contest was definitely still fun for all.

High Western conditions versus lower Eastern (US) conditions: Without the use of stealth mode, in a contest with a lower working band, a pilot relying on FLARM technology can drive harder without fearing a landout, knowing there are gliders ahead to mark thermals. This does work in the east where thermals are closer together and you may be one thermal away from a landout. Even a mediocre pilot who might not even be able to get around the course by him/herself that day can use FLARM to pick the best thermals, found by others, and do fairly well on the score sheet. I agree in most cases this will not get a pilot the win. I do believe FLARM without stealth mode jumbles the middle of the score sheet and leads to an invalid result.

So, do what you want when flying cross countries at home. However, I go to contests to see how I am stacking up against some great pilots. Stealth mode (soon to have more appropriate name) is the way to go here. It retains all the safety features it was designed to deliver, keeps your eyes outside of the cockpit where they should be and at the end of the contest period the score sheet shows which pilots have the best soaring skills.

XC

--
Dan, 5J