On 6/9/2012 4:16 PM, Chris Nicholas wrote:

As for PCAS – I have one of those too. I have only an aerial on top of
the glare shield. AIUI, transponders in gliders with only one antenna,
usually underneath, will have weak or non-existent signals upwards,
and my PCAS will only see at very shallow angles down, so would not
help in the Finland type accident if the lower glider had only a
transponder and only the upper one a PCAS.

As I have said before, the best is the enemy of the good. If everyone
waits for the best/perfection, we will have too many fatalities that
meanwhile the good – Flarm + PCAS – can help avoid some, or most,
times.

The transponder signal is so powerful (150+ watts) compared to a Flarm
signal (0.02 watts), a PCAS unit would be able to "see" a transponder
equipped glider, even in the situation in Finland. Also, the glider
above would almost certainly have it's transponder antenna on the
bottom, while the glider below would have it's PCAS antenna "on top"
(glare shield mounted) and have no trouble receiving it.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)