On Aug 16, 8:50*pm, "kirk.stant" wrote:
On Aug 16, 4:41*pm, Mike Schumann
wrote:
[snip]

But here is a question: *PowerFlarm claims it can detect ADS-B 1090ES
signals and provide bearing/rangealtitude info; it's just the legacy
Mode C transponders that will only give a range/relative altitude
warning (similar to PCAS). *Are you saying that this is not possible
and that you also need a UAT in/out box to detect *Mode -S equipped
1090ES ADS-B participants? I understand that with only a Powerflarm
you won't see UAT - only participants - but since they will probably
still need Mode C *even that isn't true - you are just down to PCAS
level of detection. *Please correct me if I'm wrong on this.

Kirk let me try to give you a useful answer to your actual questions.
Let me know if I do not cover them all enough.

Also see my more technical post in the "Flarm in the USA" thread
(Google News users see if this link works... http://bit.ly/9jOA1p)

The PowerFLARM 1090ES receiver will "see" ADS-B 1090ES data-out
equipped aircraft aka "ADS-B Direct". Which means you will start
seeing some early adopter 1090ES equipped traffic now and by the end
of this decade you will see all airliners, all fast jets, all
turboprops, and many high performance singles and twins - they all get
caught in the above FL180 requirement for 1090ES data-out in the 2020
carriage mandate. I expect you will also directly see most mid-range
and above GA aircraft as I expect many of those will meet ADS-B data-
out requirements by upgrading their Mode S transponders with 1090ES.
We'll have to wait and see what actually happens in that lower-end
market.

The PowerFLARM will see Mode C and Mode S transponders via (non-
directional) PCAS if those transponders are being interrogated by an
external source (SSR radar, TCAS, TCAD etc.). Mode S transponders that
have 1090ES data-out would be seen via 1090ES and the PowerFLARM
should automatically suppress the PCAS alert for that threat (its
technically trivial and obvious to do that).

Kirk you are correct in that UAT data-out equipped aircraft will
likely have a transponder and therefore a PowerFLARM would see them
via PCAS (if the transponder is being interrogated). Aircraft flying
in airspace that requires them to have ADS-B also requires them to
have transponders. So I expect the common configs to be Mode S with
1090ES or UAT with Mode C. Although you could have both UAT and ModeS/
1090ES or Mode S (with no 1090ES)and UAT. Powered aircraft not
required to have transponders because they don't fly in/near
controlled airspace/above 10,000' etc might voluntarily equip with UAT
only (no transponder) over time to get benefits of ADS-B data-in. But
I expect this to be a small group (who wants to build up an expensive
panel but limit severely where the aircraft can fly).

Without an ADS-B transmitter you will not reliably receive ADS-R (ie.
you won't reliably see any other UAT data-out equipped traffic) or TIS-
B (ie. you won't see the ADS-B relay of SSR radar position data for
other aircraft. And TIS-B only works where there is current SSR ATC
radar coverage). By not reliably, I mean you *really* need an ADS-B
transmitter if you you want to receive TIS-B or ADS-R. You may see
some TIS-B and ADS-R aircraft near other ADS-B data-out equipped
aircraft just not near you - not a good thing. And the danger for
people who do not understand what is going on is they will see some
ADS-B traffic on their ADS-B receiver system. But not realize they
could be missing lots of ADS-R and TIS-B traffic if they don't have a
(correctly configured) ADS-B transmitter.

TIS-B will be interesting as it can give you pretty nice traffic
information if you fly where there is radar coverage (and high enough
to be in that coverage). You also need ADS-B ground station coverage
for this to work - which is rolling out over the next few years for
the entire USA.

As pointed out by people in other threads the PowerFLARM will add TIS-
B support some time after first availability, and so until TIS-B is
supported at all in PowerFLARM it is irrelevant whether you have a
transmitter or not. There are very few UAT data-out equipped aircraft
yet so ADS-R is likely not that interesting (existing UAT deployments
up to now have been mostly in Alaska in ADS-B trials).

And to be clear the challenge here will not be PowerFLARM receiving a
TIS-B data message its working out how to effectively warn about that
traffic with as few false alarms as possible with the inherently less
precise location information that a TIS-B threat has (because the
threat location comes from SSR radar). So somebody could jump up and
down now and claim their UAT or other box receives ADS-R and
PowerFLARM does not. That claim really requires looking at details of
how the internal or external traffic display and threat warning part
handles TIS-B threats.

---

OK now some more editorializing...

Personally if I had to chose only to have an ADS-B receiver I'd much
rather have a 1090ES receiver than a UAT receiver because starting now
and getting better over time it will show 1090ES equipped airliners
and fast jets directly and over a long range and all altitude
difference (the display software always needs to let you limit that -
I don't know what PowerFLARM does there, I trust them to get it right
or it to be what glider pilots need). As better/cheaper/smaller/etc.
UAT transmitters or transponders and the GPS systems to drive become
available I can add that device and do full ADS-B.

With a UAT receiver only and no transmitter you won't reliable receive
position data from airlines, fast jets or high-performance singles.
But then if you go the next step and install an ADS-B transmitter (UAT
or 1090ES) you will only be guaranteed of seeing TIS-B and ADS-R
threats that are wihtin the "service volume" around your aircraft,
typically +/- 3,500' and within 15 nautical miles of you (there may be
velocity/time to enter threat volume enhancements of this like there
is for Mode S TIS, but good luck finding out how that works). I'd just
much rather directly receive the 1090ES ADS-B data-out from the big
fast airliners and fast jets. I might feel differently if I was
worried about a lot of GA traffic with UAT data-out. But I'm not sure
that UAT data-out is going to get much penetration in GA at all, we'll
have to wait and see.

I am not advocating relying on traffic awareness tools in the glider
cockpits as the the primary technology adjunct near high density
airliner and fast jet traffic - for that the best idea is put a Mode C
or Mode S transponder in your glider and let the combination of ATC
and TCAS II look out for you. A TCAS II RA likely gets anybody's
attention off the rental car reservations and back on flying the jet,
or at least just doing what the RA tells them.

In the USA ADS-B is going to roll out big time this decade, but right
now it still is mostly futureware. Nice neat geek stuff for early
adopters to worry about now. On the other hand I'd be concerned to
see hundreds of glider pilots in the USA rushing out now to buy Flarm
classic (Flarm protocol only) units even if they were available in the
USA (which they are not). Those pilots will likely be pleasantly
surprised what PCAS can do now outside of crowded contest
environments, and how 1090ES direct can show them some traffic and
what more they can get if they want to add ADS-B data-out in future.

The USA is different from Europe and other places where gliding is
popular, we don't have any flarm adoption here yet, and yet we are the
most advanced ADS-B strategy and rollout happening from GA up to
airliners. I really like that PowerFLARM combines both. (And to be
very clear by "most advanced" here I mean in terms of having
regulations in place that require so many aircraft to equip with ADS-B
data-out on a hard time line (by 2020), not "most advanced" as in
actually being a more sensible or coherent ADS-B or airspace strategy
compared to other locations like Europe.).

Hope that all helped.


Darryl