On Feb 12, 10:47*am, Darryl Ramm wrote:
On Feb 12, 8:24*am, JJ Sinclair wrote:

I tow with my transponder on and I'm hoping this will protect me and
my tow plane from a Boulder type scenario.
Your thoughts appreciated,
JJ

Errrrr, that is assuming the hitter has asked for flight following or
has some kind of collision avoidance equipment.
Thanks,
JJ

Barging in on Eric's reply with another long winded post...

If the threat aircraft you are worried about are on flight following
(i.e. they have a transponder and can be seen on radar by ATC and have
bothered to actually contact ATC for flight following) then by
definition you are both likely to be in radar coverage and ATC should
be able to provide traffic advisories under flight following. Of
course that or anything else here is no guarantee of protection. Of
course, especially down low where tow planes often are, many aircraft
are not under flight following.

The other part of the question is "some kind of collision avoidance
equipment". So watcha thinking?

PCAS? - See my previous post for a warm up.

Mode S TIS? - requires both aircraft to be within coverage of a radar
with TIS support. Low level coverage (where many tow planes spend a
lot of time) may not be good depending on your proximity to the
terminal radar. e.g. out of where JJ and I fly NORCAL approach radar
out of Sacramanto has TIS support, Reno approach does not. Threat
aircraft with TIS should see us on those of us with transponders on
those long mountain tows but will have problems down low.

TCAD/TAS (e.g. L3 Skywatch or Garmin 800 series)/TCAS (jets airliners
etc.)? - should provide pretty good visibility of you, independent of
ground radar or any other ground infrastructure. Prices start $10k-
$20k for GA aircraft, so more something you find in newer aircraft.
Pretty impressive stuff but it still has limits.

ADS-B? - won't see you at all because there is no ADS-B ground
infrastructure where you fly yet (CA/NV) and few aircraft have ADS-B.
Once there is ADS-B ground infrastructure then ADS-R will relay your
SSR/transponder position to ADS-B receiver equipped aircraft. If the
radar can't see you the ADS-B equipped aircraft won't know about you.
The answer there is eventually you would add an ADS-B transmitter.
e.g. a Mode S transponder like the Trig TT21 with ADS-B over 1090ES or
in future a UAT transmitter/transceiver when suitable models become
available. The ADS-B part of the transponder operates independently of
ground Radar coverage. But one (USA unique) problem there is you will
need to be within coverage of an ADS-B ground station for ADS-R so
that your 1090ES ADS-B is retransmitted for folks with ADS-B UAT
receivers and visa-versa. But eventually that ground station coverage
is going to be pretty impressive, way more than SSR, but still it's an
issue to be aware of. ADS-B is also capable of ultimately offering
other advantages (much better long range traffic awareness/tracking,
much better tracking usable for SAR, possibly ground based monitoring
by FBOs, clubs, contest tracking etc.). This ADS-B future is one
reason that if I was buying a transponder today it would likely be a
Mode S capable of 1090ES. Which in the USA effectively currently means
it would be a Trig TT21.

FLARM? - won't see your transponder and effectively no GA aircraft in
the USA are FLARM equipped and I suspect relatively few ever would be.
If you are only concerned *about glider-glider and towplane-glider
separation then FLARM is a wonderful approach but the USA never got
the start on FLARM when it should have and now ADS-B is coming which
is going to confuse this picture (and given what is happening adopting
FLARM instead of ADS-B in many places might be bad idea). But and it
is a big but -- products like PowerFLARM and TRX-1090 that combine a
FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
impressive on paper and I expect/hope to see them being used in the
USA.

And to the above add some generic issues, like -

- Pilot training/knowledge (transponder turned on, in ALT mode?
traffic awareness system turned on and the pilot known how to use it,
etc.).
- Lots of gliders in gaggles etc. may confuse a traffic awareness
system and/or the pilot
- Other non-transponder equipped aircraft in close proximity may be in
somewhat increased danger if aircraft are avoiding the transponder
equipped targets,
- etc. etc.

So while the question was about transponders in the glider and traffic
awareness systems in the threat aircraft, overall the matter is
working out which technology amongst things like transponders, ADS-B
transmitters and/or receivers, PCAS, powerFLARM type devices, etc.
make most sense for a particular situation/risk assumptions.

Just a semantic niggle but I prefer to say things like "provide or
help with traffic awareness" vs. "provide protection". But I know I
slip on this all the time as well. Oh and I don't want anybody to get
the wrong impression that technology cannot provide a hugely important
help here and the limitations like I mentioned in this thread means it
is not worth using. Human eyesight is easily fooled, visibility of
threats is easily reduced or obstructed etc. These technologies are
really useful, I just want people to think about the different choices
and their benefits and limitations and select the best technology to
help improve their flight safety.

Darryl

Well, that's comforting, I think? Guess I'll keep my mark-1 eyeball
greased up. You know I (we) almost hit a glider while on tow at
Montague at 1500 feet. I saw him and figured he was a good mile away
when suddenly he was right on us! The tow pilot kicked right rudder as
he passed and then he was headed straight for my left wing. I rolled
90 degrees left and he missed me by maybe 5 feet! The RC sailplane
guys were having their nationals and we almost hit a 12 foot white
sailpland model. Seems our tow route took us past their first turn
point about 5 miles north on Montague.

Turn on the radio and use it!
Turn on the Transponder and talk to center when necessary.........we
do that a lot around Reno.
Turn on the PCAS and monitor it.
Keep your head on a swivel..........outside the cockpit.
Cheers,
JJ