Parowan midair?

On 7/5/2010 8:46 PM, Darryl Ramm wrote:
On Jul 5, 6:38 pm, wrote:
On Jul 5, 8:25 pm, Darryl wrote:



On Jul 5, 5:35 pm, Mike
wrote:

On 7/5/2010 11:09 AM, Darryl Ramm wrote:

On Jun 16, 11:48 am, wrote:
SSA contest report indicates that 2 gliders made contact on the first
day. If the gliders are identified correctly then one continued to
win the day and the other returned to the airport missing part of one
wing and so far has no log posted.

Any more information available?

Andy.

Maybe worth noting that there was also a mid-air collision at the 31st
Worlds on Day 1 (4th July) between two standard class gliders which
was also caught on IGC flight logs. According to the contest web site
both gliders were able to land and the pilots are OK. See flight logs
for 8K and GX (reported as FX on the score sheet).

According to the contest site, one glider had an anti-collision
device, presumably Flarm, the other did not. One glider was thermaling
and the other appears to join the thermal (or at least try to avoid
the thermal circle?) but misjudges and there is a collision. That
pilot had the day disqualified and a two day suspension for what the
CD determined was dangerous flying.

As with the Parowan mid-air there was a gaggle stacked up above the
collision point and the collision involves at least one of the gliders
entering the thermal. Likely a lot of gliders to look at and I wonder
in both cases how much the pilots may have been distracted from seeing
the gliders at the same altitude by looking up at the gaggle above to
help judge the thermal location.

And as discussed in this thread earlier, continuing on task after a
collision is specifically not allowed by FAI rules (Annex A 4.1.4).
Here one glider did continue back to the contest airport/finish. He
was already on the final leg but did seem to pass up several other
closer options to land. I wonder how the CD interprets the 4.1.4 "land
as soon as practicable" requirement, but moot in this case since the
pilot was disqualified anyhow. I mention that only to point it out,
not to judge, without knowing the condition of the glider and
facilities available at the landing sites I do not know what I would
do.

Darryl

I didn't see any mention that there were additional gliders in the
vicinity of the Parowan mid-air. Is there some further documentation
that describes this?

--
Mike Schumann

Download all the IGC files for that Parowan contest day and play those
in SeeYou (EditAdd Flight and do a multiple select on all the IGC
files). There were at least three gliders in a thermal, one just
starting to leave, and the two gliders in the collision appear to be
joining that thermal below those other gliders. I have _no_ idea if
either pilot of the colliding gliders have ever commented on watching
those gliders above or whether this was a factor.

Darryl

i know one pilot who was under the colliding pilots in the same
thermal.

From the flight traces there appear to be two gliders below the
general are of the collision, neither appear to be actually working
the same thermal so I did not mention them. One of them in particular
flies towards and under the gliders a short time after the collide.

It's worth sitting down with SeeYou on a fast computer and playing
either the Parowan or WGC collision in 3D (complete with all the other
gliders) and imagine looking at that other traffic while joining a
thermal. A healthy reminder how easy this is to happen when there are
enough gliders around trying to work the same thermals.

Darryl

This is an interesting insight into this incident. Based on the
previous posts, I had assumed that this collision had occurred between
two gliders in isolation. This certainly provides some explanation on
what led up to this event.

--
Mike Schumann

On 7/5/2010 8:46 PM, Darryl Ramm wrote:
On Jul 5, 6:38 pm, wrote:
On Jul 5, 8:25 pm, Darryl wrote:



On Jul 5, 5:35 pm, Mike
wrote:

On 7/5/2010 11:09 AM, Darryl Ramm wrote:

On Jun 16, 11:48 am, wrote:
SSA contest report indicates that 2 gliders made contact on the first
day. If the gliders are identified correctly then one continued to
win the day and the other returned to the airport missing part of one
wing and so far has no log posted.

Any more information available?

Andy.

Maybe worth noting that there was also a mid-air collision at the 31st
Worlds on Day 1 (4th July) between two standard class gliders which
was also caught on IGC flight logs. According to the contest web site
both gliders were able to land and the pilots are OK. See flight logs
for 8K and GX (reported as FX on the score sheet).

According to the contest site, one glider had an anti-collision
device, presumably Flarm, the other did not. One glider was thermaling
and the other appears to join the thermal (or at least try to avoid
the thermal circle?) but misjudges and there is a collision. That
pilot had the day disqualified and a two day suspension for what the
CD determined was dangerous flying.

As with the Parowan mid-air there was a gaggle stacked up above the
collision point and the collision involves at least one of the gliders
entering the thermal. Likely a lot of gliders to look at and I wonder
in both cases how much the pilots may have been distracted from seeing
the gliders at the same altitude by looking up at the gaggle above to
help judge the thermal location.

And as discussed in this thread earlier, continuing on task after a
collision is specifically not allowed by FAI rules (Annex A 4.1.4).
Here one glider did continue back to the contest airport/finish. He
was already on the final leg but did seem to pass up several other
closer options to land. I wonder how the CD interprets the 4.1.4 "land
as soon as practicable" requirement, but moot in this case since the
pilot was disqualified anyhow. I mention that only to point it out,
not to judge, without knowing the condition of the glider and
facilities available at the landing sites I do not know what I would
do.

Darryl

I didn't see any mention that there were additional gliders in the
vicinity of the Parowan mid-air. Is there some further documentation
that describes this?

--
Mike Schumann

Download all the IGC files for that Parowan contest day and play those
in SeeYou (EditAdd Flight and do a multiple select on all the IGC
files). There were at least three gliders in a thermal, one just
starting to leave, and the two gliders in the collision appear to be
joining that thermal below those other gliders. I have _no_ idea if
either pilot of the colliding gliders have ever commented on watching
those gliders above or whether this was a factor.

Darryl

i know one pilot who was under the colliding pilots in the same
thermal.

From the flight traces there appear to be two gliders below the
general are of the collision, neither appear to be actually working
the same thermal so I did not mention them. One of them in particular
flies towards and under the gliders a short time after the collide.

It's worth sitting down with SeeYou on a fast computer and playing
either the Parowan or WGC collision in 3D (complete with all the other
gliders) and imagine looking at that other traffic while joining a
thermal. A healthy reminder how easy this is to happen when there are
enough gliders around trying to work the same thermals.

Darryl

This is an interesting insight into this incident. Based on the
previous posts, I had assumed that this collision had occurred between
two gliders in isolation. This certainly provides some explanation on
what led up to this event.

--
Mike Schumann

On Jun 29, 12:17*am, ursus wrote:
On Jun 22, 6:42*am, Mike Schumann
wrote:

There is no inherent reason that ADS-B UAT transceivers using consumer
grade GPS and RF components can't be built for the same general price
point as FLARM units. *The only difference in the hardware is frequency
and transmit power.

The FLARM RF transceiver costs about $5 in parts. The ADS-B UAT
transceiver is how much ???
Most glider pilots are in complete denial about the commercial
realities of the gliding business:
Selling and supporting an *empty* box, with no production costs, to
glider pilots could not be done below USD 600 per unit.
It is not pretty, but that's the reality if your business intends to
still be around in a few years, while supporting and innovating for
the customers...

The MITRE unit
transmits "unknown" for integrity, as that information is not available
from a consumer grade GPS chipset.

The 'consumer grade' GPS chipset in FLARM provides all the information
you ever need:
DOP, accuracy estimates, pseudorange errors, satellite health and
whatever comes in through WAAS / EGNOS...
Some of that information is also transmitted in the FLARM signal and
used for alarm evaluation.
Just because a device is FAA certified does not mean it is better, it
just means it is outdated ;-)

Another note: *FLARM and ADS-B units are not a cure alls for collision
avoidance in competition flying. *The accuracy of the GPS fixes and the
update rates (even for units meeting the FAA's latest approved specs)
are not high enough to provide collision warnings for gliders that are
sharing a thermal in a gagle. *

The update rate and relative (!) precision of the GPS used in FLARM is
by far sufficient to do collision avoidance in glider competitions.
Other factors are more limiting.
However, if you stick various FAA approved GPS's into gliders your
relative position and velocity information will not be nearly as
good...

My dear US friends; we do agree that 'classic' FLARM is not the best
solution for the US. This is why we never launched it there.
Stay tuned for PowerFLARM; it will deliver all you need, soon.www.powerflarm.com

Urs - FLARM

Urs,

QUESTION: Will PowerFLARM only be monitoring ADB-B data from 1090ES
equipped aircraft? That's my understanding after listening to Daryl
Ramm's reply. Will I be able to monitor the lat/lon and altitude of
transponder equipped aircraft from the ADB-B ground stations
rebroadcasting that information (ADS-R or ... Relay feature of the ADB-
B program). If the ADB-B ground stations relay data from both UAT
equipped aircraft and transponder aircraft, then... will I be able to
get collision advisories from the same algorithm used with FLARM to
FLARM equipped gliders?

FYI... I have ordered one of the early delivery PowerFLARMs based on
the assumption that I can hear all the ADS-B and transponder equipped
aircraft.. either directly air-to-air with the 1090ES aircraft over
through the ADS-B ground stations. Is this a correct assumption? It's
really confusing ... all this ADS-B program stuff with dual
frequencies in the U.S.

Urs, my motivation for purchasing PowerFLARM was a near mid-air I had
at the Parowan 2010 Sports Nationals. If you go to the DAY6 IGC files
and look for these logs: 06LC4541.IGC (my log - Walter Rogers : WX a
Discus 2A) and 06LC4131.IGC (Richard Pfiffner: SD a Ventus) you will
see another near mid air coming out of the first turn. Our paths
intersected with about 15 feet vertical separation. Fortunately, I saw
the converging glider at the last moment and made a severe pitch down
to miss him. Richard never saw me... Ironically (or maybe... using
good sense) I decided to purchase my PowerFLARM from Richard.

Urs, we met briefly for dinner with Dave Nadler and Lee Kuhkle at the
SSA convention in Littlerock.

Looking forward to PowerFLARM and any future software upgrades that
will help with ADS-B...

Walt Rogers, WX

On Jul 12, 10:44*pm, WaltWX wrote:
On Jun 29, 12:17*am, ursus wrote:



On Jun 22, 6:42*am, Mike Schumann
wrote:

There is no inherent reason that ADS-B UAT transceivers using consumer
grade GPS and RF components can't be built for the same general price
point as FLARM units. *The only difference in the hardware is frequency
and transmit power.

The FLARM RF transceiver costs about $5 in parts. The ADS-B UAT
transceiver is how much ???
Most glider pilots are in complete denial about the commercial
realities of the gliding business:
Selling and supporting an *empty* box, with no production costs, to
glider pilots could not be done below USD 600 per unit.
It is not pretty, but that's the reality if your business intends to
still be around in a few years, while supporting and innovating for
the customers...

The MITRE unit
transmits "unknown" for integrity, as that information is not available
from a consumer grade GPS chipset.

The 'consumer grade' GPS chipset in FLARM provides all the information
you ever need:
DOP, accuracy estimates, pseudorange errors, satellite health and
whatever comes in through WAAS / EGNOS...
Some of that information is also transmitted in the FLARM signal and
used for alarm evaluation.
Just because a device is FAA certified does not mean it is better, it
just means it is outdated ;-)

Another note: *FLARM and ADS-B units are not a cure alls for collision
avoidance in competition flying. *The accuracy of the GPS fixes and the
update rates (even for units meeting the FAA's latest approved specs)
are not high enough to provide collision warnings for gliders that are
sharing a thermal in a gagle. *

The update rate and relative (!) precision of the GPS used in FLARM is
by far sufficient to do collision avoidance in glider competitions.
Other factors are more limiting.
However, if you stick various FAA approved GPS's into gliders your
relative position and velocity information will not be nearly as
good...

My dear US friends; we do agree that 'classic' FLARM is not the best
solution for the US. This is why we never launched it there.
Stay tuned for PowerFLARM; it will deliver all you need, soon.www.powerflarm.com

Urs - FLARM

Urs,

QUESTION: Will PowerFLARM only be monitoring ADB-B data from 1090ES
equipped aircraft? That's my understanding after listening to Daryl
Ramm's reply. Will I be able to monitor the lat/lon and altitude of
transponder equipped aircraft from the ADB-B ground stations
rebroadcasting that information (ADS-R or ... Relay feature of the ADB-
B program). If the ADB-B ground stations relay data from both UAT
equipped aircraft and transponder aircraft, then... will I be able to
get collision advisories from the same algorithm used with FLARM to
FLARM equipped gliders?

FYI... I have ordered one of the early delivery PowerFLARMs based on
the assumption that I can hear all the ADS-B and transponder equipped
aircraft.. either directly air-to-air with the 1090ES aircraft over
through the ADS-B ground stations. Is this a correct assumption? It's
really confusing ... all this ADS-B program stuff with dual
frequencies in the U.S.

Urs, my motivation for purchasing PowerFLARM was a near mid-air I had
at the Parowan 2010 Sports Nationals. If you go to the DAY6 IGC files
and look for these logs: 06LC4541.IGC (my log - Walter Rogers : WX a
Discus 2A) and 06LC4131.IGC (Richard Pfiffner: SD a Ventus) you will
see another near mid air coming out of the first turn. *Our paths
intersected with about 15 feet vertical separation. Fortunately, I saw
the converging glider at the last moment and made a severe pitch down
to miss him. Richard never saw me... Ironically (or maybe... using
good sense) I decided to purchase my PowerFLARM from Richard.

Urs, we met briefly for dinner with Dave Nadler and Lee Kuhkle at the
SSA convention in Littlerock.

Looking forward to PowerFLARM and any future software upgrades that
will help with ADS-B...

Walt Rogers, WX

Walt

I'm nor sure you meant to broadcast this but I'll try to answer
(reconfirm what I think you already know?) on the more generic ADS-B
and PCAS part of your question. [And standard apology for the length
of my posts...]

PowerFLARM to the extent it has PCAS capabilities can see other
transponders being interrogated by ground (SSR Radar and in some
places multilateration systems) and airborne interrogators (TCAS, TCAD
etc). This would give you no direction information for that traffic.

PowerFLARM has a 1090ES receiver so can "see" with high accuracy
aircraft with 1090ES ADS-B data-out. That will over time include all
the airliners, fast jets, any traffic flying over FL 180, and I expect
it to include many GA aircraft who I expect will go with 1090ES data
out and not UAT to meet the ADS-B carriage requirement. Since there is
nothing else involved the line of sight range on this may be quite
significant, well beyond PCAS and FLARM (and ADS-R and TIS-B).

PowerFLARM has a 1090ES receiver so *if* you also have an ADS-B
transmitter properly configured to transmit your GPS position and ADS-
B receiver capability codes (i.e. set to show your aircraft receives
1090ES) then the ADS-B ground infrastructure will rebroadcast UAT data-
out equipped traffic over 1090ES that it is aware of within a cylinder
around your aircraft. The size of this cylinder is significantly less
than the ultimate range of UAT or 1090ES direct transmissions so this
one damper on anybody thinking they can track their glider buddies
over very long ranges in the air if there is mixed UAT and 1090ES
involved. The ADS-B data-out/transmitter you need for this would
typically be something like the Trig TT21 Mode S/1090ES transponder
but could be a UAT transmitter (or transceiver).

For the PowerFLARM or any other ADS-B receiver to see SSR radar
targets via TIS-B again the ADS-B ground infrastructure needs to know
where you are so it can broadcast possible threats in a cylinder
around you. But it will only broadcast traffic that the SSR radar
system (or multilateration in some areas - like the newly announced
Alaska deployment) can "see". There seems to be a common misconception
that ADS-B TIS-B will show transponder equipped threats over vast
areas, but it cannot show any TIS-B threats near you if you are flying
outside of traditional SSR radar (or multilateration) coverage. Again
the ADS-B data-out needed to tell the ground infrastructure where you
are would today normally be a Mode S /1090ES transponder.

One point of confusion with ADS-B traffic is some people talk about
TIS-B as if it means any traffic you see on ADS-B, it specifically
means just the SSR radar (or multilateration) traffic information
retransmitted on ADS-B. Traffic information via UAT or 1090ES data-out
direct and ADS-R is not "TIS-B" traffic.

I am concerned that in many cases pilots will not be able to tell ADS-
B receivers are not working correctly when they do not also have an
ADS-B transmitter. Gosh they will see ADS-B direct and ADS-R and TIS-B
traffic but the later two will only be traffic around other aircraft,
not necessarily yours. Unfortunately there are ADS-B receiver vendors,
especially USA based UAT receiver manufactures, who are not making
this requirement extremely clear. Some of those vendors seem to have
only woken up to this recently and are repositioning their UAT
receiver only "traffic systems" as "weather receivers" -- wanna guess
why? :-( I hope PowerFLARM in the USA makes very clear the need for an
ADS-B transmitter to enable full ADS-B traffic data-in. In Europe
today this is irrelevant so not surprising it is not called out in
European marketing material. Of course the PowerFLARM should work as a
FLARM-FLARM detector, PCAS detector and 1090ES direct traffic receiver
without any separate ADS-B transmitter.

There are large areas of the USA airspace we use where there is no SSR
coverage to enable ADS-R but even there you may get a PCAS alert
because of airborne interrogators. As more aircraft equip with ADS-B
(and I expect many will be 1090ES) you will see 1090ES targets replace
those directionless PCAS threats and unlike with PCAS you don't need
an external interrogator to see those 1090ES threats (because they
"squitter" their position ever second). It's trivial to deduplicate a
Mode S and 1090ES threat so something like PowerFLARM should be able
to suppress the PCAS warning for those 1090ES equipped threats. Even
as we pass the ADS-B carriage mandate there will be some aircraft that
stay equipped with say Mode C transponders and don't equip with ADS-B
anything, in which case there are times when you won't receive any
warnings from those aircraft. That's a scenario worth remembering with
some gliders equipped with Mode C transponders where there is no ADS-B
carriage mandate. If the transponders are not being interrogated a
PowerFLARM can't do anything for you -- you need those other gliders
to have a PowerFLARM (for FLARM-FLARM) or ADS-B data-out capability.

Maybe with the collision at Parowan, and at the World contest, and
other near misses (like yours) at both contests it may well be time to
start mandating FLARM/PowerFLARM in Contests to deal with this glider-
on-glider threat. In my mind that is a problem Flarm addresses just
about as good as it ever can be done. ADS-B futureware is really about
interacting with ATC and other traffic, and hopefully useful for long
distance tracking/SAR etc.

And we are focused on glider-on-glider issues here. Remember if the
issue is airliners and fast-jets the only thing that works properly
against those aircraft TCAS systems is a transponder (which could be a
Mode S/1090ES unit). The TCAS in those fast jets and airliners and
military transports etc. will not issue an resolution advisory (RA)
against a UAT equipped aircraft that does not also have a transponder.
The place where ATC bureaucracy and ADS-B technology meet seems to
have missed us, it really assumes your ADS-B transmitter is a
transponder or you have a separate transponder if UAT equipped.


Darryl

Darryl,

A question arising from your reply to Walt, specifically concerning
TIS-B. From your reply and PowerFLARM's literatu

A. It appears that this unit will give accurate direction, range and
relative altitude info to FLARM equipped planes, and it also will
broadcast FLARM signals to other aircraft.

B. It also appears that it will give you estimated range, relative
altitude, but no direction to Mode C and Mode S transponders that are
being interrogated.

C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info to ADS-B data-out equipped planes once a second around
other aircraft.

D. If your aircraft does have a Mode S with ADS-B out transponder,
you will get accurate direction, range and relative altitude info to
nearby aircraft with ADS-B data-out transponders once a second around
your aircraft.

We'd like point D2 to also include getting TIS-B data, meaning "SSR
radar (or multilateration) traffic information retransmitted on ADS-
B", but I can't find anywhere that PowerFLARM claims to do this. I
have an e-mail from Dr. Thomas Wittig, the developer of a competing
product (Funkwerk TM250 Traffic Monitor), that says his system
supports "ADS-B IN via Mode S 1090, but not TIS-B or TIS".

Does PowerFLARM really do TIS-B?

-John






On Jul 13, 3:23 am, Darryl Ramm wrote:
PowerFLARM to the extent it has PCAS capabilities can see other
transponders being interrogated by ground (SSR Radar and in some
places multilateration systems) and airborne interrogators (TCAS, TCAD
etc). This would give you no direction information for that traffic.

PowerFLARM has a 1090ES receiver so can "see" with high accuracy
aircraft with 1090ES ADS-B data-out. That will over time include all
the airliners, fast jets, any traffic flying over FL 180, and I expect
it to include many GA aircraft who I expect will go with 1090ES data
out and not UAT to meet the ADS-B carriage requirement. Since there is
nothing else involved the line of sight range on this may be quite
significant, well beyond PCAS and FLARM (and ADS-R and TIS-B).

PowerFLARM has a 1090ES receiver so *if* you also have an ADS-B
transmitter properly configured to transmit your GPS position and ADS-
B receiver capability codes (i.e. set to show your aircraft receives
1090ES) then the ADS-B ground infrastructure will rebroadcast UAT data-
out equipped traffic over 1090ES that it is aware of within a cylinder
around your aircraft. The size of this cylinder is significantly less
than the ultimate range of UAT or 1090ES direct transmissions so this
one damper on anybody thinking they can track their glider buddies
over very long ranges in the air if there is mixed UAT and 1090ES
involved. The ADS-B data-out/transmitter you need for this would
typically be something like the Trig TT21 Mode S/1090ES transponder
but could be a UAT transmitter (or transceiver).

For the PowerFLARM or any other ADS-B receiver to see SSR radar
targets via TIS-B again the ADS-B ground infrastructure needs to know
where you are so it can broadcast possible threats in a cylinder
around you. But it will only broadcast traffic that the SSR radar
system (or multilateration in some areas - like the newly announced
Alaska deployment) can "see". There seems to be a common misconception
that ADS-B TIS-B will show transponder equipped threats over vast
areas, but it cannot show any TIS-B threats near you if you are flying
outside of traditional SSR radar (or multilateration) coverage. Again
the ADS-B data-out needed to tell the ground infrastructure where you
are would today normally be a Mode S /1090ES transponder.

One point of confusion with ADS-B traffic is some people talk about
TIS-B as if it means any traffic you see on ADS-B, it specifically
means just the SSR radar (or multilateration) traffic information
retransmitted on ADS-B. Traffic information via UAT or 1090ES data-out
direct and ADS-R is not "TIS-B" traffic.

Nuts - I messed up the summary of this complex subject. Please correct
C and D, would you, Darryl?

The question still stands, though - Does PowerFLARM really do TIS-B?

-John

John

I'm not sure I corrected C and D to what you meant, but here goes.

On Jul 13, 6:55 am, jcarlyle wrote:
Darryl,

A question arising from your reply to Walt, specifically concerning
TIS-B. From your reply and PowerFLARM's literatu

A. It appears that this unit will give accurate direction, range and
relative altitude info to FLARM equipped planes, and it also will
broadcast FLARM signals to other aircraft.

B. It also appears that it will give you estimated range, relative
altitude, but no direction to Mode C and Mode S transponders that are
being interrogated.

C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info to ADS-B data-out equipped planes once a second around
other aircraft.

CORRECTED C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info *FROM* all 1090ES data-out eqipped aircraft once per
second.
You *MAY ALSO IF LUCKY* see *UAT* data-out equipped planes once a
second
but only around other *SUITABLY EQUIPPED* aircraft.

I'd hope people look at that scenario as completely unreliable since
the proximity/threat cylinder used by the ground infrastucture while
reasonably large in radius is likely relatively limited in altitude so
you could easily not "see" traffic via ADS-R and TIS-B even if you
might otherwise think it is relatively close. I am not sure there is a
hard commitment for this "threat cylinder" or service volume size but
typical numbers are around 15 nautical mile radius but only +/- 3,500'
around an suitable equipped aircraft. So the other nearby ADS-B data-
out equipped aircraft has to be relatively close to your altitude for
this to work. Think of it working "by accident" at times but not
something we should not every think about relying on.

It also will only work if the aircraft you are "close" enough to
either has 1090ES or UAT data-out and is transmitting the 1090ES
capability code bit -- that will cause the ground infrastructure to
transmit TIS-B around that aircraft. The ground infrastructure would
also transmit ADS-R data for UAT equipped target aircraft around that
other receiver equipped aircraft -- unless that other receiving
aircraft also happens to have a UAT receiver and is properly
transmitting the UAT capability code bit. In which case the ground
infrastructure should suppress the ADS-R data because the other
aircraft would receive the UAT data directly. Confused yet? :-) Repeat
after me... for ADS-B receivers to work properly in the USA your
aircraft must also have an ADS-B transmitter sending your GPS location
and have properly configured capability class bits (to describe your
aircraft's ADS-B receiver link type).

BTW it is also maybe worth noting that above FL180 all aircraft will
be assumed to have 1090ES (not UAT) data-out as required in the ADS-B
mandate and therefore I expect the ground infrastructure won't do ADS-
R for UAT or TIS-B to UAT receivers at these altitudes. That seems to
be backed up by some documentation I've seen. That may make UAT
devices in gliders useless in wave windows for traffic awareness/
avoidance (and the issue there may really be glider traffic staying
outside the wave window).

D. If your aircraft does have a Mode S with ADS-B out transponder,
you will get accurate direction, range and relative altitude info to
nearby aircraft with ADS-B data-out transponders once a second around
your aircraft.

Yes that is correct but technically an over-requirement. If you have a
PowerFLARM with a 1090ES receiver you will directly see other 1090ES
transmitting aircraft and in that specific scenario you do not need a
local 1090ES transponder to receive that other traffic since it comes
via ADS-B direct not ADS-R. However clearly the the other aircraft
have no chance of seeing you via 1090ES, and having a 1090ES receiver
while not transmitting any ADS-B data-out signals is a huge problem
for ADS-R and TIS-B as I've hopefully flogged to death already.

We'd like point D2 to also include getting TIS-B data, meaning "SSR
radar (or multilateration) traffic information retransmitted on ADS-
B", but I can't find anywhere that PowerFLARM claims to do this. I
have an e-mail from Dr. Thomas Wittig, the developer of a competing
product (Funkwerk TM250 Traffic Monitor), that says his system
supports "ADS-B IN via Mode S 1090, but not TIS-B or TIS".

Does PowerFLARM really do TIS-B?

I cannot speak for PowerFLARM specifically but any device that has a
1090ES receiver essentially gets TIS-B and ADS-R for "free" if the
aircraft also has the proper ADS-B data-out equipment - which yes, is
not "free" to you since you gave to buy that ADS-B data-out device.
The receiver can tell from the data if a traffic message is ADS-B
direct, ADS-R or TIS-B. The SSR radar (or multilateration) derived
positional accuracy of TIS-B is much worse that the GPS derived ADS-B
direct or ADS-R positional data and I have no idea how specific
traffic awareness/collision avoidance products will handle display and
warning for TIS-B traffic. Remember the portable avionics market is
the wild-west there is no strict standard how any of this traffic data
is handled or displayed. One option would be to ignore all TIS-B
traffic but I would be very surprised by a vendor doing this. This
problem is similar to and a bit more complex than the same problem
with the positional accuracy of Mode S TIS where the TIS system is
careful to display a threat "on top of you" when it is gets close to
you within a reasonable margin of error.


To the Funkwerk comment...

"TIS" means the Mode S TIS used in the USA where *some* terminal/
approach radars communicate SSR radar traffic to aircraft equipped
with Mode S transponders that have TIS capabilities. I never would
expect an add-on receiver box to do Mode S TIS. That capability
requires the Mode S transponder to broadcast it has TIS receive
capability and then the TIS ground infrastructure sends directed
messages to that transponder about the relative position of nearby
Mode C or Mode S equipped traffic. Because of how this works it
happens within the Mode S transponder. Most modern Mode S transponders
will support TIS. Likely of most interest in the USA is the Trig
TT21/22 transponders that do support Mode S TIS, and there are some
glider pilots in the USA starting to play with TIS traffic data from
their TT21 transponders. Clearly this is only of interest around busy
terminal/approach radar coverage areas and getting that traffic
displayed is an issue since it not the glider defacto-standard Flarm
serial port data protocol.

"Does no support TIS-B" could mean several things and it may be worth
clarifying the vendor's statement...

0. The information from the vendor could be wrong (I've managed to get
clearly wrong capability claims/misinformation from vendors in this
early market). But presumably given the source of this claim it is
accurate that the device does not support TIS-B.
1. The vendor does not want to claim TIS-B support becasue they do not
know for sure your aircraft has the proper ADS-B data-out capability
to support this.
2. The vendor has decided to suppress all TIS-B traffic data because
they do not want to handle the relative imprecise or otherwise
problematic TIS-B position reports (that would surprise me). For
European manufactures that TIS-B is not important in Europe may be a
factor here.
3. The vendor has decided to suppresses all TIS-B traffic data because
they have not yet developed the capability to handle the relatively
imprecise TIS-B position reports (and maybe other technical issues
like target ghosting/deduplication) and/or since TIS-B is not
important in a device in Europe and they have chosen to delay
implementing TIS-B support. (The question would then be when is this
support coming?).

It would not be good for an ADS-B receiver devices for sale in the USA
to not support TIS-B. It's already a confusing enough mess out there
(have I proven that yet?? :-)) without having devices selectively not
implement this. However given that we don't have ADS-B ground
infrastructure widely deployed at the moment, if this device
limitation was clearly explained by the vendor with a "coming in a
firmware update in future" promise then that would be a different
matter.

Again please get specific answers from Butterfly/PowerFLARM or
Funkwerks etc. I have never used either vendors ADS-B products.


Regards


Darryl

Darryl,

The item C and D corrections were exactly what I had in mind - thank
you! The extra comments are much appreciated, too. The situation is
truly a confusing mess; thanks for trying to make sense of it all for
us.

Regarding the ability of PowerFLARM to display TIS-B, I'll follow your
advice and send an e-mail to Butterfly. The previous message in this
thread from Urs of FLARM strongly hints that PowerFLARM is intended
mainly for the US market, so presumably PowerFLARM either does (or
will shortly) support TIS-B.

Regards,
John

On Jul 13, 2:29 pm, Darryl Ramm wrote:
John

I'm not sure I corrected C and D to what you meant, but here goes.

On Jul 13, 6:55 am, jcarlyle wrote:



Darryl,

A question arising from your reply to Walt, specifically concerning
TIS-B. From your reply and PowerFLARM's literatu

A. It appears that this unit will give accurate direction, range and
relative altitude info to FLARM equipped planes, and it also will
broadcast FLARM signals to other aircraft.

B. It also appears that it will give you estimated range, relative
altitude, but no direction to Mode C and Mode S transponders that are
being interrogated.

C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info to ADS-B data-out equipped planes once a second around
other aircraft.

CORRECTED C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info *FROM* all 1090ES data-out eqipped aircraft once per
second.
You *MAY ALSO IF LUCKY* see *UAT* data-out equipped planes once a
second
but only around other *SUITABLY EQUIPPED* aircraft.

I'd hope people look at that scenario as completely unreliable since
the proximity/threat cylinder used by the ground infrastucture while
reasonably large in radius is likely relatively limited in altitude so
you could easily not "see" traffic via ADS-R and TIS-B even if you
might otherwise think it is relatively close. I am not sure there is a
hard commitment for this "threat cylinder" or service volume size but
typical numbers are around 15 nautical mile radius but only +/- 3,500'
around an suitable equipped aircraft. So the other nearby ADS-B data-
out equipped aircraft has to be relatively close to your altitude for
this to work. Think of it working "by accident" at times but not
something we should not every think about relying on.

It also will only work if the aircraft you are "close" enough to
either has 1090ES or UAT data-out and is transmitting the 1090ES
capability code bit -- that will cause the ground infrastructure to
transmit TIS-B around that aircraft. The ground infrastructure would
also transmit ADS-R data for UAT equipped target aircraft around that
other receiver equipped aircraft -- unless that other receiving
aircraft also happens to have a UAT receiver and is properly
transmitting the UAT capability code bit. In which case the ground
infrastructure should suppress the ADS-R data because the other
aircraft would receive the UAT data directly. Confused yet? :-) Repeat
after me... for ADS-B receivers to work properly in the USA your
aircraft must also have an ADS-B transmitter sending your GPS location
and have properly configured capability class bits (to describe your
aircraft's ADS-B receiver link type).

BTW it is also maybe worth noting that above FL180 all aircraft will
be assumed to have 1090ES (not UAT) data-out as required in the ADS-B
mandate and therefore I expect the ground infrastructure won't do ADS-
R for UAT or TIS-B to UAT receivers at these altitudes. That seems to
be backed up by some documentation I've seen. That may make UAT
devices in gliders useless in wave windows for traffic awareness/
avoidance (and the issue there may really be glider traffic staying
outside the wave window).

D. If your aircraft does have a Mode S with ADS-B out transponder,
you will get accurate direction, range and relative altitude info to
nearby aircraft with ADS-B data-out transponders once a second around
your aircraft.

Yes that is correct but technically an over-requirement. If you have a
PowerFLARM with a 1090ES receiver you will directly see other 1090ES
transmitting aircraft and in that specific scenario you do not need a
local 1090ES transponder to receive that other traffic since it comes
via ADS-B direct not ADS-R. However clearly the the other aircraft
have no chance of seeing you via 1090ES, and having a 1090ES receiver
while not transmitting any ADS-B data-out signals is a huge problem
for ADS-R and TIS-B as I've hopefully flogged to death already.

We'd like point D2 to also include getting TIS-B data, meaning "SSR
radar (or multilateration) traffic information retransmitted on ADS-
B", but I can't find anywhere that PowerFLARM claims to do this. I
have an e-mail from Dr. Thomas Wittig, the developer of a competing
product (Funkwerk TM250 Traffic Monitor), that says his system
supports "ADS-B IN via Mode S 1090, but not TIS-B or TIS".

Does PowerFLARM really do TIS-B?

I cannot speak for PowerFLARM specifically but any device that has a
1090ES receiver essentially gets TIS-B and ADS-R for "free" if the
aircraft also has the proper ADS-B data-out equipment - which yes, is
not "free" to you since you gave to buy that ADS-B data-out device.
The receiver can tell from the data if a traffic message is ADS-B
direct, ADS-R or TIS-B. The SSR radar (or multilateration) derived
positional accuracy of TIS-B is much worse that the GPS derived ADS-B
direct or ADS-R positional data and I have no idea how specific
traffic awareness/collision avoidance products will handle display and
warning for TIS-B traffic. Remember the portable avionics market is
the wild-west there is no strict standard how any of this traffic data
is handled or displayed. One option would be to ignore all TIS-B
traffic but I would be very surprised by a vendor doing this. This
problem is similar to and a bit more complex than the same problem
with the positional accuracy of Mode S TIS where the TIS system is
careful to display a threat "on top of you" when it is gets close to
you within a reasonable margin of error.

To the Funkwerk comment...

"TIS" means the Mode S TIS used in the USA where *some* terminal/
approach radars communicate SSR radar traffic to aircraft equipped
with Mode S transponders that have TIS capabilities. I never would
expect an add-on receiver box to do Mode S TIS. That capability
requires the Mode S transponder to broadcast it has TIS receive
capability and then the TIS ground infrastructure sends directed
messages to that transponder about the relative position of nearby
Mode C or Mode S equipped traffic. Because of how this works it
happens within the Mode S transponder. Most modern Mode S transponders
will support TIS. Likely of most interest in the USA is the Trig
TT21/22 transponders that do support Mode S TIS, and there are some
glider pilots in the USA starting to play with TIS traffic data from
their TT21 transponders. Clearly this is only of interest around busy
terminal/approach radar coverage areas and getting that traffic
displayed is an issue since it not the glider defacto-standard Flarm
serial port data protocol.

"Does no support TIS-B" could mean several things and it may be worth
clarifying the vendor's statement...

0. The information from the vendor could be wrong (I've managed to get
clearly wrong capability claims/misinformation from vendors in this
early market). But presumably given the source of this claim it is
accurate that the device does not support TIS-B.
1. The vendor does not want to claim TIS-B support becasue they do not
know for sure your aircraft has the proper ADS-B data-out capability
to support this.
2. The vendor has decided to suppress all TIS-B traffic data because
they do not want to handle the relative imprecise or otherwise
problematic TIS-B position reports (that would surprise me). For
European manufactures that TIS-B is not important in Europe may be a
factor here.
3. The vendor has decided to suppresses all TIS-B traffic data because
they have not yet developed the capability to handle the relatively
imprecise TIS-B position reports (and maybe other technical issues
like target ghosting/deduplication) and/or since TIS-B is not
important in a device in Europe and they have chosen to delay
implementing TIS-B support. (The question would then be when is this
support coming?).

It would not be good for an ADS-B receiver devices for sale in the USA
to not support TIS-B. It's already a confusing enough mess out there
(have I proven that yet?? :-)) without having devices selectively not
implement this. However given that we don't have ADS-B ground
infrastructure widely deployed at the moment, if this device
limitation was clearly explained by the vendor with a "coming in a
firmware update in future" promise then that would be a different
matter.

Again please get specific answers from Butterfly/PowerFLARM or
Funkwerks etc. I have never used either vendors ADS-B products.

Regards

Darryl

Butterfly has very good customer support friendly and prompt!

They told me that PowerFLARM does not yet display TIS-B information.
The hardware supports it, but their target for displaying TIS-B is
Summer 2011, via a software update.

Reinforcing what Darryl has said, to get TIS-B data sent to your
plane you need a proper GPS connected to a Mode S transponder, with
the transponder configured to (1) send ADS-B Out with position data
and (2) send the ADS-B In capability bit.

-John

On Jul 13, 4:35 pm, jcarlyle wrote:
Darryl,

The item C and D corrections were exactly what I had in mind - thank
you! The extra comments are much appreciated, too. The situation is
truly a confusing mess; thanks for trying to make sense of it all for
us.

Regarding the ability of PowerFLARM to display TIS-B, I'll follow your
advice and send an e-mail to Butterfly. The previous message in this
thread from Urs of FLARM strongly hints that PowerFLARM is intended
mainly for the US market, so presumably PowerFLARM either does (or
will shortly) support TIS-B.

Regards,
John

On Jul 13, 2:29 pm, Darryl Ramm wrote:

John

I'm not sure I corrected C and D to what you meant, but here goes.

On Jul 13, 6:55 am, jcarlyle wrote:

Darryl,

A question arising from your reply to Walt, specifically concerning
TIS-B. From your reply and PowerFLARM's literatu

A. It appears that this unit will give accurate direction, range and
relative altitude info to FLARM equipped planes, and it also will
broadcast FLARM signals to other aircraft.

B. It also appears that it will give you estimated range, relative
altitude, but no direction to Mode C and Mode S transponders that are
being interrogated.

C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info to ADS-B data-out equipped planes once a second around
other aircraft.

CORRECTED C. If your aircraft does not have a Mode S with ADS-B out
transponder, you will still get accurate direction, range and relative
altitude info *FROM* all 1090ES data-out eqipped aircraft once per
second.
You *MAY ALSO IF LUCKY* see *UAT* data-out equipped planes once a
second
but only around other *SUITABLY EQUIPPED* aircraft.

I'd hope people look at that scenario as completely unreliable since
the proximity/threat cylinder used by the ground infrastucture while
reasonably large in radius is likely relatively limited in altitude so
you could easily not "see" traffic via ADS-R and TIS-B even if you
might otherwise think it is relatively close. I am not sure there is a
hard commitment for this "threat cylinder" or service volume size but
typical numbers are around 15 nautical mile radius but only +/- 3,500'
around an suitable equipped aircraft. So the other nearby ADS-B data-
out equipped aircraft has to be relatively close to your altitude for
this to work. Think of it working "by accident" at times but not
something we should not every think about relying on.

It also will only work if the aircraft you are "close" enough to
either has 1090ES or UAT data-out and is transmitting the 1090ES
capability code bit -- that will cause the ground infrastructure to
transmit TIS-B around that aircraft. The ground infrastructure would
also transmit ADS-R data for UAT equipped target aircraft around that
other receiver equipped aircraft -- unless that other receiving
aircraft also happens to have a UAT receiver and is properly
transmitting the UAT capability code bit. In which case the ground
infrastructure should suppress the ADS-R data because the other
aircraft would receive the UAT data directly. Confused yet? :-) Repeat
after me... for ADS-B receivers to work properly in the USA your
aircraft must also have an ADS-B transmitter sending your GPS location
and have properly configured capability class bits (to describe your
aircraft's ADS-B receiver link type).

BTW it is also maybe worth noting that above FL180 all aircraft will
be assumed to have 1090ES (not UAT) data-out as required in the ADS-B
mandate and therefore I expect the ground infrastructure won't do ADS-
R for UAT or TIS-B to UAT receivers at these altitudes. That seems to
be backed up by some documentation I've seen. That may make UAT
devices in gliders useless in wave windows for traffic awareness/
avoidance (and the issue there may really be glider traffic staying
outside the wave window).

D. If your aircraft does have a Mode S with ADS-B out transponder,
you will get accurate direction, range and relative altitude info to
nearby aircraft with ADS-B data-out transponders once a second around
your aircraft.

Yes that is correct but technically an over-requirement. If you have a
PowerFLARM with a 1090ES receiver you will directly see other 1090ES
transmitting aircraft and in that specific scenario you do not need a
local 1090ES transponder to receive that other traffic since it comes
via ADS-B direct not ADS-R. However clearly the the other aircraft
have no chance of seeing you via 1090ES, and having a 1090ES receiver
while not transmitting any ADS-B data-out signals is a huge problem
for ADS-R and TIS-B as I've hopefully flogged to death already.

We'd like point D2 to also include getting TIS-B data, meaning "SSR
radar (or multilateration) traffic information retransmitted on ADS-
B", but I can't find anywhere that PowerFLARM claims to do this. I
have an e-mail from Dr. Thomas Wittig, the developer of a competing
product (Funkwerk TM250 Traffic Monitor), that says his system
supports "ADS-B IN via Mode S 1090, but not TIS-B or TIS".

Does PowerFLARM really do TIS-B?

I cannot speak for PowerFLARM specifically but any device that has a
1090ES receiver essentially gets TIS-B and ADS-R for "free" if the
aircraft also has the proper ADS-B data-out equipment - which yes, is
not "free" to you since you gave to buy that ADS-B data-out device.
The receiver can tell from the data if a traffic message is ADS-B
direct, ADS-R or TIS-B. The SSR radar (or multilateration) derived
positional accuracy of TIS-B is much worse that the GPS derived ADS-B
direct or ADS-R positional data and I have no idea how specific
traffic awareness/collision avoidance products will handle display and
warning for TIS-B traffic. Remember the portable avionics market is
the wild-west there is no strict standard how any of this traffic data
is handled or displayed. One option would be to ignore all TIS-B
traffic but I would be very surprised by a vendor doing this. This
problem is similar to and a bit more complex than the same problem
with the positional accuracy of Mode S TIS where the TIS system is
careful to display a threat "on top of you" when it is gets close to
you within a reasonable margin of error.

To the Funkwerk comment...

"TIS" means the Mode S TIS used in the USA where *some* terminal/
approach radars communicate SSR radar traffic to aircraft equipped
with Mode S transponders that have TIS capabilities. I never would
expect an add-on receiver box to do Mode S TIS. That capability
requires the Mode S transponder to broadcast it has TIS receive
capability and then the TIS ground infrastructure sends directed
messages to that transponder about the relative position of nearby
Mode C or Mode S equipped traffic. Because of how this works it
happens within the Mode S transponder. Most modern Mode S transponders
will support TIS. Likely of most interest in the USA is the Trig
TT21/22 transponders that do support Mode S TIS, and there are some
glider pilots in the USA starting to play with TIS traffic data from
their TT21 transponders. Clearly this is only of interest around busy
terminal/approach radar coverage areas and getting that traffic
displayed is an issue since it not the glider defacto-standard Flarm
serial port data protocol.

"Does no support TIS-B" could mean several things and it may be worth
clarifying the vendor's statement...

0. The information from the vendor could be wrong (I've managed to get
clearly wrong capability claims/misinformation from vendors in this
early market). But presumably given the source of this claim it is
accurate that the device does not support TIS-B.
1. The vendor does not want to claim TIS-B support becasue they do not
know for sure your aircraft has the proper ADS-B data-out capability
to support this.
2. The vendor has decided to suppress all TIS-B traffic data because
they do not want to handle the relative imprecise or otherwise
problematic TIS-B position reports (that would surprise me). For
European manufactures that TIS-B is not important in Europe may be a
factor here.
3. The vendor has decided to suppresses all TIS-B traffic data because
they have not yet developed the capability to handle the relatively
imprecise TIS-B position reports (and maybe other technical issues
like target ghosting/deduplication) and/or since TIS-B is not
important in a device in Europe and they have chosen to delay
implementing TIS-B support. (The question would then be when is this
support coming?).

It would not be good for an ADS-B receiver devices for sale in the USA
to not support TIS-B. It's already a confusing enough mess out there
(have I proven that yet?? :-)) without having devices selectively not
implement this. However given that we don't have ADS-B ground
infrastructure widely deployed at the moment, if this device
limitation was clearly explained by the vendor with a "coming in a
firmware update in future" promise then that would be a different
matter.

Again please get specific answers from Butterfly/PowerFLARM or
Funkwerks etc. I have never used either vendors ADS-B products.

Regards

Darryl

On Jul 14, 7:57*am, jcarlyle wrote:
Butterfly has very good customer support friendly and prompt!

They told me that PowerFLARM does not yet display TIS-B information.
The hardware supports it, but their target for displaying TIS-B is
Summer 2011, via a software update.

Reinforcing what Darryl has said, to get TIS-B data sent to your
plane you need a proper GPS connected to a Mode S transponder, with
the transponder configured to (1) send ADS-B Out with position data
and (2) send the ADS-B In capability bit.

Just to be clear on terminology. With the ADS-B "-B" revision devices
i.e. DO-260B (1090ES) and DO-282B (UAT) which we will all really be
dealing with there is not an "ADS-B In" capability bit, there are
separate capability code bits for 1090ES-in and UAT-in. The Mode S/
1090ES transponder or UAT transmitter/transceiver needs to be
configured to transmit the correct capability code bit (or bits) that
reflects what ADS-B receiver(s) with traffic display/warning
capabilities are in use. In the case of having a PowerFLARM in your
cockpit you would set the "1090ES-in" bit in whatever ADS-B
transmitter(s) you have on board.

"-A" rev devices currently on the market will have an "ADS-B in"
capability bit, say in a Mode S/1090ES transponder that says the
aircraft has a 1090ES receiver. The Trig TT21/22 is such an example,
and I understand Trig will be coming out with a "-B" firmware update
(until then nothing stops TT21/22 users playing with ADS-B/109ES if
they want to including with a PowerFLARM when available, it should all
work fine). And kudos to Trig for making it very easy to configure the
capability code, with a simple menu on the Transponder and having this
clearly documented.

--

BTW remembering this is the wild west, there is no standard for how
you set these bits, or even a guarantee that the end-user can
configure this in their ADS-B transmitters as they say add or remove a
portable device like a PowerFLARM in their cockpit (this is likely an
issue that should be looked at in whatever the SSA is doing with ADS-
B). Some modern glass panel aircraft might well just not allow the
pilot to change these bits in their 1090ES transponder so a portable
1090ES or UAT *receiver* just won't work properly in that aircraft.
Not that there is likely anything that will clue the hapless pilot
into this. Something all the makers of portable ADS-B receiver only
traffic systems should be being clear to potential users about (and
maybe related to why some of those UAT receiver vendors seem to be
repositioning their products to be mostly weather vs. traffic
awareness products). ADS-B receiver products should also be at least
looking at their own link-layer and confirming the local aircraft is
transmitting the capability code bit for that receiver and clearly
warning the user if it can't detect this. You would think this is
actually a RTCA standards requirement, or at least an obvious safety
issue and simple to do so vendors would be doing this,.... ah don't
hold your breath (likely another issue that should be looked at in
whatever the SSA is working on with ADS-B).


Darryl