On Thursday, July 26, 2012 5:27:49 PM UTC-7, Evan Ludeman wrote:
On Jul 26, 7:32*pm, son_of_flubber > wrote:
> On Thursday, July 26, 2012 6:31:57 PM UTC-4, Evan Ludeman wrote:
> > The skies of VT and NH are incredibly empty.
>
> Except near the airports where the newbie pilots are concentrated. (My original point.) Though the worse case is 3-4 trainers in the air, a towplane, and 3 XC launching at 1 pm.
>
> Sometimes I think that in this neighborhood a Trig Mode-S transponder would be more valuable than a PowerFlarm as both Springfield and Sugarbush are right on Victor Airways to Burlington and Lebanon. *4-5 biz jets not uncommonly land at VSF on Saturday afternoon. *TCAS is a beautiful thing.
>
> The PCAS function (transponder in the neighborhood) of PFlarm is valuable for GA traffic (as Tony mentioned).

As worst cases go, that's pretty light, except about the jets. I'm
astounded that you are getting that much jet traffic.

IIRC you get painted pretty low at VSF, so pcas should be useful
there. Go very far North though, and you have to be at 4 or 5000 to
get interrogated. Not sure how good Powerflarm pcas will be for
jets. I see pcas targets by eyeball almost always before I get the
info from flarm unless they are below/behind me. No way am I getting
pcas at 5 miles. Maybe 2 miles. Is that enough for jets? Is any
pcas device enough for jets? If I saw "4 or 5" bizjets at my altitude
in one day from my sailplane cockpit, I'd have a transponder this
time next week.

-Evan / T8

No disagreement from me on concerns about PCAS range and suitability of that with fast jets, but the "painting" aspect is often not an issue, especially if you have reasonable heavy jet traffic in the area--their TCAS tends to do a good job of interrogating lots of transponders (but not interrogate their own transponder -- but two jets will get you that).

Best thing for gliders in areas of high jet traffic density is to be equipped with a transponder - let the jet TCAS II see you, much larger range than PCAS and the only technology that directs the pilots to deviate to avoid a collision. The transponders also get you seen by ATC directing those jets.

An interesting aspect of using PCAS near high density GA and fast jet traffic I've seen is "whoa there is a lot more stuff out there than I thought" and then more willingness to install a transponder. Of course that only applies to busier airspace areas, I'm not a fan of pushing transponders in general (would rather see than money spent on PowerFLARM, better training, SPOT trackers, etc.)

Darryl