Another FLARM thread

On Aug 13, 3:04*pm, johngalloway wrote:
On 13 Aug, 19:00, Andy wrote:



The FLARM in US thread has taken so may twist and turns I decided to
start a new one.

I was prompted by a discussion on u.r.a.s to read the SGU FLARM trial
report again. *I had read it when it was first published but since
FLARM was not available in US at that time I quicky forgot about it.
It's worth a read:

http://flarm.net/news/SGU_Flarm_Report.pdf

I know that John, one of the trial participants, drops in on ras
sometimes and would ask him to comment whether there has been an
update to this report or whether any of the suggested software changes
were implemented. *I'm particularly interested in whether a usable
heading referenced display was ever developed.

The uras thread that brought me back to the SGU trial report was a
heated discussion on what to do when FLARM alerts to a head on
situation. * It seems that, despite the increased use of FLARM in UK,
there is no standardized training in how to respond to its indications
and alerts.

That thread can be found at

http://uras.gliderpilot.net/?op=s2&id=30079&vt=

Do FLARM user in other counties have any sort of standardized training
in FLARM use or is it generally a case of read the manual and go fly
with it?

How many manufacturers have a current FLARM product? *Do all FLARM
manufacturers use the same algorithms or will the system response in a
given situation be manufacturer dependent? *So far I'm only aware of
one manufacturer interested in the US market but it may be important
to know the answer when referencing reports of user experience with
other FLARM *systems.

Andy

Andy,

We have not published any follow up to the 2007 SGU trial and there
has been no modification to the Flarm software or hardware to correct
the direction of the alert display from track to heading. *In practice
the track versus heading issue that we identified is only a
significant problem when the crabbing angle is very noticeable such as
low airspeed ridge or wave soaring. * It rarely shows in thermal
soaring.

I think that the 2007 trial report is still valid - the main
difference is that Version 4.** software, released later, seems to be
subtly better in terms of appropriateness of alerts.

There is as yet no formalised training in the UK for Flarm users.
Some of us think that this is very important - especially as we now
have a generation of ab initios who are learning to fly in Flarm
equipped gliders.

There are several manufacturers who sell equipment that includes Flarm
functionality under license. *As Darryl explains, they all use the
same algorithm. * Given the close proximity that gliders operate in
and their distinctive modes of flight it would make no sense to use
different algorithms within one region otherwise there could easily
arise the situation that one unit predicts a collision risk whereas
the other does not.

I see Flarm as primarily being the glider-optimised collision alert
software and the discussions of "Flarm versus ADSB" as a red herring
because whatever hardware platform is used a *single common predictive
algorithm is essential. *Any ADSB manufacturer/s that wished to
include an effective glider anti-collision system alternative to Flarm
would have to arrange between manufacturers to write and agree common
algorithms ( could they do that and would they have the gliding
expertise?) or use the Flarm algorithm under license - which would
make far more sense.

As regards the u.r.a.s. debate about how to respond to head on
alerts, *the main thing to emphasise is that Flarm is an aid to see
and avoid. *The alert tone is far more important to me than the
directional display. *In the cruise when an alert sounds look out and
around. *If the alert is from ahead it will usually be from a glider
that you can acquire visually very quickly. *If not then a quick
glance at the display is helpful. *If the the other glider is in our
blind spot then my personal view is that a small but early correction
according to the internationally recognised rules of the air is the
best action. * When thermalling with other Flarm equipped gliders the
Flarm audio alert mainly serves as an intermittent warning to keep
looking out and the visual display is of limited use - as the Flarm
manual points out.

As regards the view that Flarm is no use unless all gliders have one,
I don't think that is entirely true - the value is basically in
proportion to the fraction of gliders that have it, but that value is
magnified for an individual if he tends to fly in the company of
specific other gliders that are also Flarm equipped. *All, I think, of
the gliders at our club that I am likely to fly cross country with
have Flarms as do all the club two seaters - the most intensive
circuit fliers. So although there are still many non-Flarmed glides
gliders the ones that I am most likely to encounter are Flarm
equipped.

John Galloway

A question, to John or anyone who knows-
FLARM has skipped the US but now we hope PowerFlarm will come (I have
one on order). For some the cost of PowerFlarm will be too much but
the cost of Flarm only (no mode c detection) would make it more likely
to get bought/installed. Do we think Flarm only is a coming soon? I
see that Butterfly makes them.

Brian