Sigh... (USA)

PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. Best that
PCAS would tell you is that there are "n" gliders close to you. It
certainly can't give collision warning.

-Evan Ludeman / T8

On Jun 9, 8:23*pm, Evan Ludeman wrote:
PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. *Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. *Best that
PCAS would tell you is that there are "n" gliders close to you. *It
certainly can't give collision warning.

-Evan Ludeman / T8

Sorry Evan but that is not completely correct. While I agree that
PCAS can only offer very limited collision avoidance it certainly does
help. Speak of the devil I have video to prove it! Check out the
following which is just one of many videos showing close sailplane
formation and PCAS proximity warnings. Note my PCAS warns me that I
am drifting too close to the other transponder equip ship. I am all
for Power Flarm and have one on order but please note that the PCAS
does offer at least a little bit of help. Better than nothing...that
is when it works. My Zaon PCAS has stopped working 3 times with no
warning other than it didn't alert me to a close aircraft giving me a
hint that it stopped working again. Grrrr!

http://www.youtube.com/watch?v=n2H4SQpjRxc

The PCAS warnings come at :18, :27 (note how the sailplane is drifting
towards me), :46, 1:14 and on and on throughout the video. Again,
I'll take Flarm any day of the week but I guess they have to start
shipping our brick units first. Another Grrr.

Take care,
Bruno - B4

On Jun 9, 11:09*pm, Bruno wrote:
On Jun 9, 8:23*pm, Evan Ludeman wrote:

PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. *Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. *Best that
PCAS would tell you is that there are "n" gliders close to you. *It
certainly can't give collision warning.

-Evan Ludeman / T8

Sorry Evan but that is not completely correct. *While I agree that
PCAS can only offer very limited collision avoidance it certainly does
help.

Don't be at all sorry if it works for you!

Different environments.

In dense gaggles in crappy wx at 15s we got *frequent* flarm alerts...
because the flying was just that close. Was it annoying? Not
exactly. All the alerts were meaningful. Think of having a back
seater with omnidirectional vision calling out traffic (4 oclock
high.... 3 oclock level, etc), stuff you needed to know about, mostly
already knew about. Did it prevent a collision? We can't know.
Flarm tells you early enough that the corrections needed are small and
the conflicts never develop into scary situations. The most
interesting alert was when Flarm called out three targets at once, oy.

If we'd all been on TXPs and PCAS, a) half the time we'd have had no
coverage because were below the radar, b) other times we'd have had 30
contacts inside a half mile and 400 vertical feet. I don't see how
PCAS could have provided meaningful information in that environment
and that's the environment I was thinking of. Your mileage, and
collision avoidance requirements may vary!

-Evan Ludeman / T8