FLARM.....for good, or evil??

On 10/29/2010 11:37 AM, kirk.stant wrote:
Mike, I think you do not understand the fundamental difference between
ADS-B and FLARM.

ADS-B is designed for aircraft that do not want to fly close to each
other, and want/need long range situational awareness. Thats probably
where the whole ground station setup comes from - with all it's
disadvantages (coverage, latency, accuracy, etc.) It's a great system
for IFR traffic, and for GA flyers out sightseeing, but it sucks for
gliders in a gaggle or running a ridge.

FLARM, on the other hand, is specifically designed for aircraft
(gliders, helicopters) that often want to fly close to each other,
safely. In a gaggle, running a ridge, heading for the really nice Cu
near the glider field, on the Whites - gliders inherently will
congregate to find the best lift. That is the threat environment
FLARM is designed to cope with. And it's a proven item.

In a perfect world, there would be a SuperFLARM that would add some
sort of ADS-B in/out capability, so the benefits of both would be
present. But until then, FLARM addresses the immediate concern of
many, if not most glider pilots the best. A PowerFLARM, combined with
a mode s transponder, gives a glider most of the useful threat warning
capability of a full up ADS-B setup, and all the advantages of FLARM -
if FLARM is widely adopted by the US soaring community.

But if no-one gets ADS-b in their gliders (show of hands out there?),
then it's of no use in preventing the biggest historical threat -
glider on glider collisions.

I'm planning on getting a PowerFLARM next season to replace my PCAS.
I hope you will to, while waiting for your ADS-B to be installed.


Kirk
66

I think that you have a fundamental misunderstanding of ADS-B. ADS-B is
a general purpose system that is designed to permit aircraft to announce
their position and velocity vectors to anyone who is interested. For
all practical purposes, it has the same accuracy, latency, etc. of FLARM
based systems. It doesn't make any difference if aircraft are flying in
close proximity or not.

FLARM does the same thing and then adds another layer of collision
detection logic on top of that, which is specifically optimized for the
glider world. There is no reason that the same logic could not also be
added on-top of an ADS-B based position sensing technology. In fact,
PowerFLARM claims to be doing this using their 1090ES IN capability, if
the user has ADS-B Out installed.

The ground station ADS-B infrastructure is being deployed for 4 reasons:

1. To provide translation of ADS-B transmissions between UAT and 1090ES
(an unfortunate necessity due to the FAA's decision to go with 2 ADS-B
formats in the US)

2. To transmit TIS-B data. This lets ADS-B IN equipped aircraft see
the position and altitude of Mode C and S Transponder equipped aircraft
which are not yet outfitted with ADS-B transmitters.

3. To transmit additional weather and NOTAM information.

4. To detect ADS-B equipped aircraft so that they can be displayed on
ATC radar displays.


--
Mike Schumann

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

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

On Oct 29, 11:30*am, Mike Schumann
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

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

"Mike Schumann" wrote in message
...
What evidence do you have that there are plans to turn off TIS-B after 2020?
Some TIS stations are already gone. See this AOPA blurb:
http://www.aopa.org/whatsnew/newsite...051101tis.html Google for more.

Vaughn

On Oct 29, 2:53*pm, "vaughn" wrote:
"Mike Schumann" wrote in message

... What evidence do you have that there are plans to turn off TIS-B after 2020?

Some TIS stations are already gone. See this AOPA blurb:http://www.aopa.org/whatsnew/newsite...is.html*Google for more.

Vaughn

Vaughn

Actual this is talking about Mode S TIS (sometimes incorrectly called
TIS-S). Which is not related to ADS-B TIS-B although some of the
concepts are similar. ("concepts" is my favorite work at the
moment...)

Mode S TIS is (or was if your local service has been decommissioned) a
great service used in the USA that uplinks terminal/approach radar
traffic information to a Mode S transponder capable of receiving TIS
data. (Yes Mode S transponders are fancy enough the can receive uplink
data as well as downlink data, but the uplink is not the same as
1090ES data-in).

Mode S TIS transponder advertise to the approach radar that is has TIS
capability then the approach radar TIS processor calculates threats
within an ~8nm radius cylinder +/- 3k' or so (its actually more
complex than that but I'll spare you the pain) around the client
aircraft and uplinks that data to the client transponder (using
relative distance and direction). This requires you are within
coverage of a TIS equipped SSR terminal (not enroute) radar and you
have a Mode S transponder that supports TIS and it is connected to a
compatible display. Enroute radar can't provide TIS for multiple
reasons including the slow scan/update rates, traffic volumes, etc.

The Mode S TIS decommissioning issue was as the FAA upgraded some
terminal SSR systems they did not want to pay to add the TIS support
to those systems, even if the SSR radar they were upgrading had
previously had it. To me this was a very poor decision since Mode S
TIS was encouraging many GA aircraft to equip with traffic displays
and encouraging pilots to use traffic awareness systems - which would
have been a good segway into ADS-B. To rub salt into this the are some
realtively low-cost add-on Mode S TIS processor systems that use
omnidirectional antennas (the Mode S TIS data-uplink does not has to
go though the SSR radar directional antenna) that companies proposed
to the FAA and were turned down on. But in the FAA's defense here is
they are just a funding starved organization trying to do a lot. Maybe
too much, but that is debatable.

Around the places like the San Francisco Bay Area where I live Mode S
TIS still provides very useful traffic information to many GA
aircraft. The other advantage of Mode S TIS is is is relatively a low-
cost feature to add to any Mode S transponder. For example the pretty
standard Garmin GTX 33 and GTX 330 transponders come with it included.
The Trig TT21 that is being used in gliders also comes with Mode S TIS
-- but you need to connect it to display that support the "TIS serial
protocol" -- e.g. something like my Gamin 496 -- and that's the same
whole issue that the UAT and 1090ES receivers not designed for glider
cockpits have with not supporting the Flarm serial dataport protocol
that is widely supported by display products in our cockpits.

Darryl

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

Darryl, by the way, the USAF (and I assume USN/Marines/Army) is in the
process of installing Mode S (with 1090 ES) in many (if not all) of
it's planes. C-17s are already using this mode in Europe, as can be
seen on the sites that show Mode S tracks. And I personally know that
F-15Es are being equipped with Mode S.

What this means is that there is the potential for using the
PowerFLARM 1090 ES detection capability to provide accurate and timely
warning of military aircraft - such as fighters on low level routes,
and in MOAs. That would be awesome - I'm sure we have all been
surprised by a pair of fighters at some time.

What we may need is for SSA to push the DOD to require all military
aircraft equipped with Mode S transponders to use them at all times
when practicable and explain why.

This capability in itself makes a PowerFLARM a necessity in some
areas!

Cheers,

Kirk

On Oct 29, 2:27*pm, "kirk.stant" wrote:
Darryl, by the way, the USAF (and I assume USN/Marines/Army) is in the
process of installing Mode S (with 1090 ES) in many (if not all) of
it's planes. *C-17s are already using this mode in Europe, as can be
seen on the sites that show Mode S tracks. *And I personally know that
F-15Es are being equipped with Mode S.

What this means is that there is the potential for using the
PowerFLARM 1090 ES detection capability to provide accurate and timely
warning of military aircraft - such as fighters on low level routes,
and in MOAs. *That would be awesome - I'm sure we have all been
surprised by a pair of fighters at some time.

What we may need is for SSA to push the DOD to require all military
aircraft equipped with Mode S transponders to use them at all times
when practicable and explain why.

This capability in itself makes a PowerFLARM a necessity in some
areas!

Cheers,

Kirk

Kirk

Thanks for the info.

BTW if you look at current goodies like the BAE F15 CIT it is a
combined Mode 4 IFF transponder *and* interrogator that also does Mode
S etc. i.e. it can interrogate a Mode C or Mode S transponder in your
glider and paint you on the tactical display and you can also see
their Mode S transponder. All assuming they want to let you see them
of course. See pdf brochure at http://tiny.cc/alo9f its a sexy piece
of technology. I believe that system is going into recent F15
refreshes.

Effectively all the heavy transports and tankers have Mode S, because
the USAF has equipped them with TCAS II systems with require Mode S in
the TCAS equipped aircraft (but will work with Mode C or Mode S in the
threat aircraft) and also probably for compatibility with ATC in
Europe and elsewhere. With Europe mandating 1090ES data out for
aircraft over 5,700kg it makes sense for large military transports to
equip with that even ahead of USA domestic requirements - even if the
military may be technically exempt from requirements. In any serious
threat situation that transponder and especially 1090ES data-out is
going to be turned off, they have "aim here" written all over them. It
will be interesting to see what military transports etc. do with ADS-B
data-in/CDTI to enhance TCAS II displays.

I agree that seeing both transport and fast military traffic via long-
range 1090ES data-in like that in the PowerFLARM could be very useful
- especially in knowing general areas where this traffic is operating.
But if military traffic is a major concern maybe a more effective
thing you can do is to equip with a Mode C or Mode S transponder.
Effectively all heavy military transports and tankers have TCAS II
equivalent that can see your transponder and provide RA instructions
to the crew, military controllers can see your transponder on their
SSR radar and many tactical aircraft equipped with radar/IFF can see
you transponder systems - *if* they have the IFF in the right
interrogator mode, which they might not in all situations. I would
talk to the flight ops or RAPCON etc. at the military facility about
their aircraft equipment and operating proceeds. I'd much rather have
ATC controllers, TCAS II and IFF systems keep us separated than rely
on doing something to avoid them at the last minute.

One of our local traffic concern are heavy transport and busy mixed GA
around Travis AFB and all that traffic effectively has TCAS II and the
local RAPCON sees all out transponder equipped gliders but is blind in
large areas due to radar scatter from windmills and cannot see any
primary glider targets. They provide great service, including flight
following to gliders and are very easy to work with. Oh yes and when
are all those USAF RAPCON getting ADS-B critical services so they can
see UAT equipped traffic (without transponders). Who knows, again my
head hurts too much thinking about that (OK I lied I'm asking around
on that one).

Darryl