Since I started flying in 1973 REAL MEN (:-D) manually switched their
transponders from Off to STBY to ON, then from OFF to STBY to ON to ALT,
then from OFF to STBY to On to GND to ALT.Â* Now all you weenies need to
have a "system" to do it for you. Is the switch count too high?Â* I guess
the next thing you'll all need is instant coffee or beer in cans...

Happy December!Â* Winter is just three weeks away.

On 12/1/2019 7:54 AM, Eric Greenwell wrote:
Darryl Ramm wrote on 11/30/2019 10:13 PM:
On Saturday, November 30, 2019 at 7:30:25 PM UTC-8, Mike Schumann wrote:
On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell
wrote:
Darryl Ramm wrote on 11/29/2019 10:36 PM:
Again if you are installing TABS just set the transponder squat
switch to
"None" and use manual ON/ALT switching on the transponder.

I might forget to switch it correctly. Would using the "gear is down"
switch to change between ground/airborne be a sensible choice? The
pattern
(and the first 500'-1000' after the takeoff) would be flown showing
the
glider was on the ground, of course, but that might be better than
having
the whole flight showing as on the ground.



If you use a squat switch with a Trig transponder, I believe that
also puts
the Transponder into GRND mode, so it wouldn't be responding to
interrogations.Â* The one place you do want ADS-B OUT and your
transponder
operating is in the pattern.Â* That's where half of the midairs occur.
Turning off ADS-S B OUT or your transponder as soon as you lower the
gear is
a really bad idea.

Mike has an important point. Please do not dick around and end up
disabling a
safety system. If you are in the air the transponder needs to be in
ALT mode.

What is actually going on is a bit more messy, but "not responding to
interrogations" is a useful summary. In GND mode Mode-S transponders
will
actually reply to direct addressed Mode-S interrogations, and do some
other
things, but that a far from a necessary set for the transponder to
operate
normally (e.g. it can't be acquired as a target by SSR).Â* It will keep
transmitting ADS-B Out, but messages encode the glider is on the
ground, and
some message content changes slightly. How all different ADS-B
receivers all
respond to that is uh anybody's guess.Â* I just have an image in my
mind of
somebody seeing a transponder reply LCD thingy blink when in GND mode
at some
time and say "ha see it's replying OK". Ah nope, it's replying to a
small
subset of stuff. Flying in GND mode is a bad idea.

I thought it might be a bad idea, but it was easy to do, so worth
asking. When I do a TABS install, I will use an airspeed sensor - easy
and cheap enough.


--
Dan, 5J