Mike Schumann wrote:
On Wednesday, January 21, 2015 at 2:06:21 AM UTC-5, Darryl Ramm wrote:
On Tuesday, January 20, 2015 at 9:55:35 PM UTC-8, wrote:
On Tuesday, January 20, 2015 at 11:57:33 PM UTC-5, WaltWX wrote:
Daryl,

First, I have no intention of equipping with ADS-B out and agree that
there is little or no value to gliders. My interest in having a Trig
that is compliant for ADS-B out is just in case FAA changes their mind
and mandates it for gliders in 2020. Yes, the complexity of
certification and cost are prohibitive. I'm just trying to consider
whether it's worth it for an extra $300 and slightly higher power usage to be "ready".

My main interest is to protect myself against fast jets and airliners
etc in busy airspace.

Thanks for all your explanations and background in this discussion...
although it sure makes a decision on which unit to purchase difficult.
I agree the TT21 is probably all I need for the time being.

Walt Rogers WX

If you fly in busy airspace, with airliners and fast jets etc. Please
install a transponder. Whether it is a Trig T-21 or TT-22 has really
no difference for the usefulness of that transponder. If you intend
in future to go though all the money, complexity and hassle (uh why?)
of installing ADS-B data-out as well then the question about TT-22
TSO-C166b certification may become relevant.


There is a lot of value in outfitting a glider with ADS-B OUT.
Specifically, this is required to reliably receive TIS-B traffic from
ADS-B ground stations.

There are a lot of lower cost ADS-B OUT solutions in the pipeline. At
OSHKOSH last summer L3 announced a complete 2020 compliant ADS-B IN/OUT
solution that was suppose to cost $2-3K. This system was suppose to
ship by the end of 2014. I suspect that there will be a number of
significant additional product introductions at the next OSHKOSH show.

ADS-B is going to be a very important collision avoidance tool for
those of us who fly recreationally near major metropolitan airports,
where the mid-air threats are not just gliders, but other GA and airline aircraft.

Technology like TIS-B as an aspiration are great, who would not love to
see all transponder equipped aircraft nearby, but it's got to be
affordable, its got to have low-power consumption and it's got to be
compatible with what is in glider cockpits already, and pilots have to
understand some restrictions on how the technology actually works/what
it actually provides.

TIS-B probably has little interest to most glider pilots. It requires
you to equip with a currently expensive ADS-B data-out system, also have
ADS-B data-in that is TIS-B compatible (PowerFLARM unfortunately is not)
and then only shows you other aircraft within coverage of FAA ground
radar, with radar and system time delay limited positional accuracy of
that other traffic. And all this that once these so far-mythical
affordable systems become available and installable in a glider would
then only be that useful for a short time until much of the GA fleet
equip with ADS-B out, and ideally 1090ES Out (which it looks like most
GA folks will... and many airliners and fast jets already are..). Which
by then makes TIS-B uninteresting for gliders as you would hopefully
receive much better traffic information via ADS-B/1090ES direct in your
good old PowerFLARM.

L3 seems to be stumbling a bit with the Lynx system (what you are
referring to), they are around 6 months late on making available
specifications they promised half way back in 2014, so while it would be
great if they did something I'd not hold my breath. And any system is
dead in the water for gliders unless it has low-power consumption.. so
that will be the first spec to look at. And prices I've seen mentioned
for Lynx starting around $2k for a 1090ES Out with a GPS source would be
impressive.. but that starting price does not include the ADS-B In
option... I've not seen any indication of pricing that includes that
(maybe it is $3k bit that just seems pretty-amazingly cheap for such a
system from L3). And besides power the next thing is can the traffic
display be compatible with what is used in a glider... most gliders
don't have space for yet another traffic display, and if anything need
ADS-B data output in a Flarm compatible way to be displayed on a display
they already have in the panel. And then if you do happen to have a
PowerFLARM already there is a slight annoyance of how to deal with two
sources feeding a display, and worse how to deduplicate traffic
warnings, but all doable if somebody wants to build a custom
box/software to do this, but it is not clear who that would be...

It does look like Lynx (or well it's Optional ADS-B in part) and other
ADS-B In systems from folks like Garmin are going the right way and
doing dual-link 1090ES and UAT In. The mess the FAA created with
dual-link basically ends up with the only reliable way to see all ADS-B
traffic is to carry both a UAT and 1090ES receiver. And with much of the
GA fleet lightly to be transmitting 1090ES the FAA could have saved all
this effort and just gone 1090ES only. Sad really how badly this was messed up.

Equipping with a plain old a Mode C or Mode S transponder still can give
you pretty good bang for the buck if you fly near lots of GA traffic,
and PCAS in PowerFLARM can be a nice low cost/low complexity help for
you to be aware of that traffic. Equipping with a transponder lets ATC
see you, can let GA aircraft "see" you if they are equipped with PCAS,
TCAD, Mode S TIS (if your local approach SSR provides that) and full
ADS-B systems in the right circumstances via TIS-B. Of course if L3 or
others ever ships a 1090ES Out system with built-in IFR GPS source for
the same price as a Mode-S transponder alone then and it's low enough
power for a glider then I expect folks to go that route. Multiple
vendors are talking about single box ADS-B Out solutions, ultimately
it's a required step to get ownership and install costs down in GA
aircraft that don't already have a IFR GPS systems.

It is very unfortunate that PowerFlarm doesn't support TIS-B. That would
make it a great solution for glider pilots who want all the advantages of
ADS-B IN and also have FLARM capability.

The PCAS functionality in PowerFlarm doesn't come close to matching the
functionality you get with TIS-B. You have no idea where the conflict
aircraft is, only its altitude and approximate distance (based on some
very crude received power level measurements). That's a whole lot
different than TIS-B which shows you the absolute position of the target
to the same resolution that is available on an air traffic controller's radar screen.

While TIS-B will eventually disappear after we have universal deployment
of ADS-B OUT, we still have ~6 years before that happens.

Every glider pilot is going to have to make their own decisions on the
optimal solution they want to deploy. If you are a contest pilot flying
in remote locations where radar coverage is spotty, TIS-B might be of
limited utility and FLARM may be more important. If you are a
recreational pilot flying near a major metropolitan airport, getting an
ADS-B solution that supports TIS-B, even if it just interfaces with
ForeFlight on your iPhone, could save your life.

Actually TIS-B only functions if the ground station sees an ADS-B out
target. They then compute any target in your "donut" and transmit that data
out. No ADS-B out no TIS-B for you. You can still piggyback on someone
else's signal but TIS-B isn't a broadcast of all targets all the time.

Peter