On Oct 29, 2:24*pm, Mike Schumann
wrote:
On 10/29/2010 2:51 PM, Darryl Ramm wrote:



On Oct 29, 11:30 am, Mike
wrote:
On 10/29/2010 12:33 PM, kirk.stant wrote:

Mike, you have just confirmed what I just suspected. *Again, ADS-b is
designed for keeping airplanes that want to stay apart, apart. *And
yes, I understand exactly what the ground infrastructure is for, and
it's not gliders - It's for IFR air traffic control and GA planes
working their way through bad weather, checking on the latest NOTAMs
at their destination. Sure, "someone" could develop software and
hardware to use ADS-b to do what FLARM has been doing for the past 10
years, BUT THE CHANCE OF THAT HAPPENING IN THE NEAR FUTURE IS A CLOSE
APPROXIMATION OF ZERO!

Can't you understand that this isn't a zero sum game? *NOTHING
prevents you from having FLARM now (in Europe) or next year (in the
US, hopefully) and later, if and when ADS-b becomes affordable and
useable in a glider cockpit, installing ADS-b in their glider. *And
that even if the FAA gave a free UAT to every aircraft out there,
FLARM would still be useful in the glider community?

The two systems overlap each other, but occupy different requirement
niches.

Kirk
66

The ground infrastructure is for EVERYONE! *Glider pilots are probably
not as interested in weather or NOTAMs. *They are interested in seeing
Mode C / S equipped aircraft (both GA and Jets) in their vicinity. *This
is the BIG reason you should care about ADS-B ground stations.

The PowerFLARM proponents claim that it will handled 1090ES ADS-B
Inputs. *Does this include TIS-B data? *What is the plan for PowerFLARM
equipped aircraft to transmit ADS-B Out data so that the TIS-B data is
visible? *If PowerFLARM can do that, then it will be a killer product,
not just for the glider world, but also for GA in the US.

--
Mike Schumann

Ground infrastructure, once it is deployed and in-service, is for
everybody within the coverage volume of that infrastructure and who is
properly equipped to use it. Unfortunately those requirements will
exclude many gliders and popular glider locations which may makes it
less useful than the combination of Flarm (esp. for glider threats)
and PCAS (esp. for GA threats) in PowerFLARM for many of us - assuming
we can get good mutual equipage of Flarm products within the glider
community. But that seems off to a good start.

As has been discussed on r.a.s. already Flarm have talked about
PowerFLARM having a software update in 2011 that will support TIS-B.
Since this is of any interest in the USA only, requires currently
expensive and difficult to install ADS-B data-out equipment, and TIS-B
capability has limited deployment today I hope Flarm does not waste
any time working on TIS-B support before the product ships. It is easy
to understand why TIS-B needs more work - TIS-B service data has
relatively high positional uncertainty compared to Flarm or ADS-B
direct data because the target information is from an SSR radar (or
multilateration) source and radar scan time delays and position
extrapolation induced errors. Some traffic displays might well just
ignore all this and treat the position of a TIS-B threat as if it is
highly precise and that could be a problem when you get close.... who
knows how all those third party PDA traffic display/processor devices
handle this today. I expect with Flarms focus on the glider market
they will work to get this right for our use.

To see threat aircraft via TIS-B the GBT ground infrastructure needs
to be deployed and integrated into the appropriate enroute and
terminal radar facilities and the threat aircraft need to to be within
that SSR radar coverage and your glider needs to be equipped with ADS-
B data-out (so the ADS-B ground infrastructure knows you are there)
and you obviously need some form of ADS-B data-in and TIS-B capable
traffic display/threat processing (PowerFLARM will do the later two
after the software update). If you do all that you will "see" TIS-B
data for all transponder equipped threats within +/-3,500' and a 15nm
cylinder around your aircraft's position. You may also see other TIS-B
"threats" within service volumes around other ADS-B data-out equipped
"client" aircraft but pilots really must not rely on that. I point it
out to explain to people why you may see a TIS-B threat on an ADS-B
data-in only system and that threat may magically appear and dissapear
from the display (but still be a very real threat)--if that happens
with PowerFLARM when used without ADS-B data-out at least the PCAS
should be screaming at you as the threat gets close.

TIS-B requires the deployment of FAA ground infrasttucutre and
integration of that with the appropriate radar facilities (enroute and
terminal facilities are rolled out differently). That won't be
complete for several more years. Pilots need to understand the
situation for their local area -- is TIS-B available and from enroute
and/or terminal radar and what are the coverage volumes for those
services.

I have no doubt that the directional and longer range capabilites of
TIS-B compared to PCAS is a nice thing. But given the current cost and
other issues around equipping with ADS-B data-out as well as ADS-B
data-in to receive TIS-B service makes this impractical at least for
the near future for most glider pilots. Most of my time talking with
pilots about TIS-B is to correct misunderstandings they have, for
example assuming that ADS-B data-in alone will provide TIS-B in their
cockpit.

Given the limited SSR coverage in many places we fly gliders and lack
of GBT (ADS-B ground based transceiver) coverage at many GA airports
and many popular gliding locations I do not see TIS-B as a replacement
for PCAS. I've seen lots of alerts on my Zaon MRX when definitively
outside of SSR coverage (presumably those transponders were being
interrogated by TCAS/TCAD equipped aircraft). A bit of the irony then
is that the PowerFLARM by being 1090ES not UAT based can easily
include PCAS capability and if a pilots wants to install 1090ES data-
out in future (as prices fall, products become more practical and
installation issues go away as they will) then that is a great
option.

Also just to point out a timing issue -- worrying about TIS-B for
gliders only makes sense if adoption becomes important within a
certain time window - for most after ~2013 as widescale TIS-B service
infrastructure deploy but before 2020 since after that TIS-B service
is expcted be turned off since the assumption is it won't be needed as
all those transponder equipped aircraft will be transmitting ADS-B
data-out and link-layer conversion vis ADS-R will provide all that is
needed. ADS-R will provide wider area and more accurate coverage than
TIS-B. I hope cost and install issues do decrease - I want to play
with all this with 1090ES data-out from a Trig TT21 in my (certified)
glider with PowerFLARM doing 1090ES data-in.

In discussing ADS-B ground infrastructure being "for everybody" it is
also worth noting that most deployments of ADS-B ground infrastructure
in the USA today do not include the ADS-R service yet and this
"critical service" (in FAA speak) will take several more years to roll
out widely. So if you have a UAT receiver you won't see any of those
1090ES data-out equipped airliners etc. who are amongst the early ADS-
B data-out adopters and of interest to many of us in location like
Reno. With a PowerFLARM with 1090ES data-in we see those directly, but
similarly those of us with PowerFLARM and its 1090ES data-in won't see
anybody with UAT data-out (until the ADS-R service is locally
available and then only when we are within coverage of the GBT - and
that will have significant coverage gaps for us to worry about,
especially close to terrain).

Again with any complex system like this the devil is in the practical
details...

Darryl

What evidence do you have that there are plans to turn off TIS-B after
2020? *The current 2020 ADS-B out rules only require equipage in certain
airspace environments. *There are lots of areas where there will be
ADS-B ground station and radar coverage, where ADS-B out equipage will
be optional, and there may be a significant number of Mode C/S
transponder equipped GA aircraft still flying around without ADS-B.

While there are a lot of remote areas of the country where TIS-B will
not be available to glider pilots, there are also a lot of areas close
to metro areas where a lot of recreational pilots fly where ADS-B ground
stations with TIS-B support are or will be turned on a lot quicker than
you are leading people to believe.

I would certainly encourage the PowerFLARM people to figure out how to
support TIS-B as quickly as possible (which of course will require them
to figure out a practical, cost effective way for pilots to add ADS-B
Out equipment to their cockpits). *If this becomes a practical product
feature, it would be a huge advance over PCAS and would open up the GA
market to their system, which is 10x larger than the glider market in
the US.

--
Mike Schumann

The FAA has long stated their desire to decommission TIS-B some time
after 2020. There were objections to this in the comments to the NPRM
and in the final ADS-B rule making document the FAA promised it "will
evaluate the benefits of continuing TIS–B past the 2020 rule
compliance date" but I parse that as a non-committal committal and I
believe from other information this is still the goal. If you have
different information please let us know.

Remember also the cost saving from decommissioning of some existing
primary radar and SSR infrastructure is a part of what is driving the
cost justification for the ADS-B part of Nextgen. So you would loose
those source of TIS-B input data. By no means is all that SSR
infrastructure being proposed for decommissioning, but enough terminal
coverage is likely to be removed to be significant. And it may be an
interesting political juggling act for the FAA to claim to want to
turn off significant SSR radar infrastructure on on hand and about in
parallel want to keep alive TIS-B than would need input from those
sources. I have concerns about the uncompromising of terminal primary
radar and SSR infrastructure both from a redundancy and domestic
airspace national security virewpoints.

I'm not trying to lead anybody to think anything about schedules,
beyond saying that full deployment is scheduled for 2013. The fact
alone that ADS-R is virtually non-existent is a surprise for most
pilots--an important issue. Pilots need to check locally for the
details of what and when services are being deployed they can use. I
don't think most pilots hear about ADS-B and think en-route vs.
terminal vs. essential services vs. critical service deployment but
again because all this is complex they need to be thinking about that.
But what is the point of arguing, your the biggest proponent of this
stuff being used in the short term--maybe you could help explain the
USA ADS-B roll-out/schedule (in practical detail not concept) to help
people make equipage decisions.

Darryl