On Jul 24, 3:05*am, "Mike Schumann" mike-nos...@traditions-
nospam.com wrote:
[snip] There is nothing stopping anyone from developing the same or
more
sophisticated traffic warning logic in these attached devices

AIUI, Flarm broadcasts the projected path of its host glider. I think
it recognises the difference betaween thermalling (circles) and
cruising.

Would "these attached devices" be able to transmit that?

Similarly, a Flarm receiving such broadcasts compares them with its
host glider predicted path, and alerts if collision likely, and if not
simply displays what is the nearst unit.

[snip] " . . . I believe that an audio alert that gives you traffic
warnings relative to your current heading and altitude (i.e. "Traffic
closing at 100 knots, 1/2 mile 3 o'clock, 100 ft low and climbing")
would be very useful for glider applications."

Flarm gives indications relative to track, not heading. It does not
know which way the glider is pointing, it only knows the history of
its GPS positions. Mostly this is not a big difference, but ridge or
wave soaring in strong winds make a huge diference. I expect many
pilots have experienced track at almost 90 degrees to heading, and
even 180 degrees in high wave (i.e. flying too slowly! - I certainly
have). I am told, by people who use Flarm in these conditions, that
you get used to the indications being relative to track.(I have had my
Flarm for too short a time to yet experience this.)

What sort of device would be able to indicate relative to heading? Is
anyone going to develop such a device?

On the general point, I have been engaged in dialogue and
correspondence in the UK about Flarm and PCAS. My own conclusions are
that:

In some places, glider-glider (or glider-tug) collisons are far more
likely than glider-unrelated power. For those, if you can only fit
one, fit Flarm. In the UK that is true for almost all gliding clubs.
Most UK glider-glider collisons are over or close to the gliding site
they both took off from. Therefore, it does not take the whole country
fitting them to provide a benefit for the individual pilot - if all
your mates have them, they are the most likely ones for you to collide
with, so it helps with the biggest scenario of risk you have. It could
be beneficially done club by club.

There may be places where glider-unrelated power collisions are a
significant risk. For those, if the unrelated power is likely to have
a transponder, then PCAS provides a degree of assistance. You don't
need a transponder yourself, if you can detect a threat and take
avoiding actions. I don't know about the USA, but in the UK, 3 of the
5 such collisions over the last 39 years were also near or immediately
over the gliding site of the gliding participant. They are also more
likely to incur fatalities - 6 people died in the 5 UK collisions. Too
many winch launch sites have overflights of unrelated powered
aircraft, at or below winch launch heights, and they are sometimes
seen too late by ground crews when a winch launch is taking place -
one of the 5 UK collisions killed two glider pilots while winch
launching. So I think such sites would benefit from having a PCAS on
the ground, at the launch point, too. Mine, when on the ground, has
alerted an overflying airctaft, and has indicated the presence of
approaching ones long before the eye can pick them up.

So if you can afford two units, and the glider can accommodate them, I
think Flarm + PCAS is becoming the best answer. Yes, it needs Flarm to
be widely adopted - but as I said, that can be on a club-by-club
basis.

There may be places where a glider really needs, or at least can
benefit from, having a transponder too. I gather that applies in parts
of the USA. It is not very obvious than it would help most UK glider
pilots to any great extent, but I would have fitted one by now if I
could. Unfortunately, the EASA regulatory regime under which most UK
gliders now operate prevents many, including mine, easily, legally, or
economically doing it. (I am not going to get into the details here -
believe it or not as you wish, but it is a fact.)

I think everybody realises that transponders alone provide no
anticollision protection. They only do so if combined with one or more
of: ATC providing a radar service; TCAS; and/or PCAS or similar. In
the USA, perhaps you can always get radar service, maybe glider pilots
tolerate the workload it takes, and use ATC frequencies instead of
dedicated gliding channels. That is certainly not the case in the UK,
except in a few places where using ATC really helps. Most of us, most
of the time, keep away from airspace where ATC has to be contacted,
and use the radio if at all only on gliding channels.

In the long term, ADS-B may provide a solution that make everything
interoperable with everything else. I suspect that is 10 or more years
away. meanwhile, I would like to see a significant reduction in the
annual death toll of colliding glider pilots. I particularly don't
want to be a statistic myself, while waiting for the dream solution.
So I bought Flarm and PCAS. I think that wowuld bring big benefits to
most glider pilots. If only one, choose the one that addresses the
risk you most encounter, based on accident figures for the sort of
place you mostly fly. (Does anybody have the USA data for glider
collisions, how many and what sort of place?) If you can afford, and
the glider can accommodate, all three, then go for the transponder
too.

IMHO.

Chris N.