Meeting to discuss FLARM in the USA

"Eric Greenwell" wrote in message
news:LOsUi.39$MW.24@trndny05...
Mark Dickson wrote:
On Oct 26, 8:32 am, 5Z wrote:
I understand FLARM does a good job of recognizing
which gliders in the
gaggle may pose a threat. Correct?

-Tom
Incorrect.
Flarm is merely a distraction in gaggles. Its value
is between thermals and approaching them. The makers
obviously believe this aswell because it has a 5 minute
mute facility specifically intended for use gaggles.

Does it warn you when a new glider approaches to join the gaggle? That
would be useful, even if the gliders already in the gaggle were muted.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Keep in mind that Flarm, and for that matter ADS-B, are basically systems
for aircraft to exchange position information in real time. What the
receiving aircraft does with that information is determined by software.
Software, by its nature, is constantly under development.

This means that we can expect constant improvement in how traffic conflict
is determined and how that information is displayed. We're still very early
in this game.

Bill Daniels

As someone else noted, ADS-B is purely a way to broadcast the position,
speed, direction, and altitude of all aircraft. The ability to interpret
this data and display or announce it in a way that is meaningful to a pilot
will vary greatly from one potential implementation to another.

Obviously, gliders need some very specialized collision avoidance algorithms
on the receiving end, as we tend to intentionally fly in close proximity to
one another. However, that does not mean that the system should be turned
off in a gaggle. Rather it means that we need more intelligence in glider
specific ADS-B units, so we can determine if there is a collision threat in
a gaggle, or if there is an orderly structure to the gliders in the thermal
that does not pose any issues. There are lots of times that I am in a
gaggle and lose sight of the other glider(s). It would be great to have a
way to know where the gliders are that I can't see, in a way that does not
provide sensory overload.

It would be very interesting if someone could come up with a low cost ADS-B
transceiver that had an interface to a PDA (if desired) to handle the
processing and display of inbound traffic and weather data. That would make
it easy for a lot of different people to get very creative with innovative
collision avoidance software, without incurring the big costs associated
with hardware development and with certification issues.

Mike Schumann

"5Z" wrote in message
ups.com...
On Oct 25, 1:57 pm, "Mike Schumann" mike-nos...@traditions-
nospam.com wrote:
We don't need FLARM. What we need is a low cost version of ADS-B that is
affordable for glider pilots.

I agree.

But... I doubt ADS-B will have the smarts to provide intelligent
warnings and ignore false alerts due to the close proximity we fly in.

I understand FLARM does a good job of recognizing which gliders in the
gaggle may pose a threat. Correct?

-Tom




--
Posted via a free Usenet account from http://www.teranews.com

If you mute Flarm it mutes all contacts. The problem
with it in a gaggle (all Flarm equipped) is that it
is constantly going off and it is difficult if not
impossible to be sure who it is warning you about;
it would certainly not be possible to tell whether
the conflict was in the gaggle or joining (at least
not with my Swiss Flarm). That said, I don't mute
mine and it is a valuable aid to lookout. When thermalling
alone or with one other glider it gives early warning
of other gliders approaching your thermal and overall
it is a valuable addition to a good lookout; as long
as others have it. I have only had limited use of
mine and my experiences may well be contradicted by
others.

At 21:18 26 October 2007, Eric Greenwell wrote:
Mark Dickson wrote:
On Oct 26, 8:32 am, 5Z wrote:
I understand FLARM does a good job of recognizing
which gliders in the
gaggle may pose a threat. Correct?

-Tom
Incorrect.
Flarm is merely a distraction in gaggles. Its value
is between thermals and approaching them. The makers
obviously believe this aswell because it has a 5 minute
mute facility specifically intended for use gaggles.

Does it warn you when a new glider approaches to join
the gaggle? That
would be useful, even if the gliders already in the
gaggle were muted.

--
Eric Greenwell - Washington State, USA
* Change 'netto' to 'net' to email me directly
* 'Transponders in Sailplanes' http://tinyurl.com/y739x4
* 'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org

We have been using Flarm devices for the last two seasons and are very
satisfied with its performance, between thermals, near airports and in
gaggles. Yes it does warn you of threats in a gaggle and it tends to
be surprisingly appropriate (risque de resource intempestive for
instance). There may be situations where alarms bother more than they
inform, but it's not very frequent, and I personally don't care the
extra noise. It's always a shock when you pass a glider coming from
the front without having the warning (because it is not equipped with
flarm); and despite looking out you surprise yourself not having
noticed that particular glider. Don't hesitate: try it in different
situations, and you will see how effective the algorithms are. I have
been using it for x-country flights, competitions and passenger
flights near the airport, at home and abroad (France): not without any
more on a day with hundreds of gliders in the air.
In addition, cables, towers and other obstacles are listed; flying in
the Alps knowing the flarm will tell you about these terrible dangers
is so much better. No, you can't rely entirely on flarm warnings, but
it does add a lot to your own vigilance.

Pascal Duport
Geneva
Groupe genevois de vol à voile - Montricher

Aviation Consumer's current issue has an article on traffic-detection
systems. It points out that mode S is already going away and ADS-B in
only just beginning to be installed. and that a defect of ADS-B is
that several seconds may elapse between the time aircraft A replies to
the radar facility, the facility processes the signal and calculates
vector information, and then broadcasts this. So this isn't going to
help as much as we'd like in gaggles, never mind that it won't be
available everywhere for a long time.

It sounds as though FLARM is available and functional. It might be
possible for pilots to cooperatively use it without an FAA
imprimateur, though the FTC will have jurisdiction over the use of
frequency.

Dan

On Oct 26, 4:53 pm, "Mike Schumann" mike-nos...@traditions-
nospam.com wrote:
As someone else noted, ADS-B is purely a way to broadcast the position,
speed, direction, and altitude of all aircraft. ...

...we need more intelligence in glider specific ADS-B units,
so we can determine if there is a collision threat in
a gaggle, or if there is an orderly structure to the gliders in the thermal
that does not pose any issues....

On Oct 25, 1:57 pm, "Mike Schumann" wrote:
We don't need FLARM. What we need is a low cost version of ADS-B that is
affordable for glider pilots.

I agree.

But... I doubt ADS-B will have the smarts to provide intelligent
warnings and ignore false alerts due to the close proximity we fly in.

-Tom

We should be able to attend the SSA convention in February.
If you wish we can make a presentation about FLARM.
We have no reservation whatsoever to sell FLARM in the US, legal
questions can be solved, but we would like to get positive feedback
from the US soaring community before doing so.

Some comments about the recent r.a.s. posts:

The frequency in all FLARM units can be set by software, therefore all
units work worldwide.
The transceiver is designed to meet FCC rules, but we have not yet
fully verified this.
It transmits at less than 1% duty cycle and (currently) 10mW.

"Nuisance alarms" versus "real alarms" will always be a hot topic for
any collision warning device in soaring.
1) We can and will further reduce "nuisance alarms" based on pilot
feedback and our own continuing research.
2) If the pilot "behaves well" in a gaggle he is much less likely to
suffer from "nuisance alarms" as the predicted trajectory will not
cross someone else's.
3) One of the unique features of FLARM is that each aircraft performs
and transmits its own trajectory prediction based on aircraft type,
flight path history and other parameters. This results in superior
system performance, especially in high density or heterogeneous
traffic environments.
It also safes a lot of processing power as each unit only needs to do
one sophisticated prediction and then just compares all received
trajectories to it.
Position and velocity vector is not sufficient information for a smart
collision alert, and don't get me started on the cheap "transponder
sniffer" devices... ;-)

Urs --- FLARM

danlj wrote:
Aviation Consumer's current issue has an article on traffic-detection
systems. It points out that mode S is already going away and ADS-B in
only just beginning to be installed. and that a defect of ADS-B is
that several seconds may elapse between the time aircraft A replies to
the radar facility, the facility processes the signal and calculates
vector information, and then broadcasts this. So this isn't going to
help as much as we'd like in gaggles, never mind that it won't be
available everywhere for a long time.

I haven't read the article, but the above is only partially correct.
This only refers to the case of an ADS-B equipped aircraft detecting a
nearby Mode C or S equipped aircraft. When two ADS-B (more correctly,
UAT) equipped aircraft are in proximity, they communicate directly with
minimal delay, the ground network and radar facilities are not involved.

It sounds as though FLARM is available and functional. It might be
possible for pilots to cooperatively use it without an FAA
imprimateur, though the FTC will have jurisdiction over the use of
frequency.

If a FLARM-like device using an FCC approved frequency was available, we
could use it without FAA approval. But, our glider population density
is much lower than Europe, except in a few areas, and other aircraft are
a hazard these days in many areas. ADS-B UAT is a FLARM-like device
with regulatory issues that make it difficult to develop a low cost
device. It seems to me that the best thing to do is attack the
regulatory problem, so that gliders, balloons, light sport aircraft,
etc. can all participate in the system at a lower cost...

Marc

wrote:
Position and velocity vector is not sufficient information for a smart
collision alert,

What more information are you using besides position, pressure altitude,
and GPS-derived velocity vector to calculate a trajectory prediction?
If adequate information and processing power is available, than it
should not matter in the least whether the prediction is made by the
transmitter or receiver...

Marc

On 26 Oct, 18:18, Ramy wrote:
On Oct 26, 9:07 am, Ian wrote:
SNIP

[1] and have no intention of doing so: I'm profoundly sceptical about
a further increase in the number of things to fiddle with and focus on
inside the glider. Why not just look out?

Because your human eyes can't detect most threats on time to avoid it,
especially gliders and especially if they are comming from behind or
the side.

The pilots of these gliders should be able to see me - if they are not
busy concentrating on yet another electronic gadget in the cockpit.
Anyway, my human eyes have successfully detected /all/ threats in time
to avoid them so far. How common are midair glider collisions?


Ian

On 27 Oct, 17:08, pascal wrote:

It's always a shock when you pass a glider coming from
the front without having the warning (because it is not equipped with
flarm); and despite looking out you surprise yourself not having
noticed that particular glider.

I wonder how well you look (ie one looks) out when a little part of
the brain assumes that flarm would have reacted to anything that
mattered?

Ian