On Oct 19, 6:49*am, Darryl Ramm wrote:
On Oct 18, 9:25*pm, Derek C wrote:





On Oct 19, 4:35*am, Darryl Ramm wrote:

On Oct 18, 7:17*pm, Derek C wrote:

Darryl- Hide quoted text -

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Yes, but in one area in Europe where transponders are mandatory for
gliders, the ATC controllers often ask the pilots to turn them off on
busy gliding days because of information overload on their screens!
Hence they are a total waste of money and battery power! *Now if we
could get a cheap, low power instrument that provides a universal
electronic collision avoidance system, that would be different.

Derek C

The situation with the Schiphol TMA has come up in this thread earlier
and it should never have happened. There are various filters that
could have been put in place/developed for the screen display data to
avoid that overload. It should have been tested before the deployment..
It should be an embarrassment to the Dutch authorities and a caution
to others but it is not a fundamental problem with transponders or ATC
systems.

The search for low-cost universal device is a dangerous red herring.
That's what has caused so much confusion and mis-set expectations
around ADS-B and UATs in the USA. There are separate threat scenarios
and legacy technologies (transponders, SSR, TCAS, etc.) and new
systems (ADS-B) coming that are *not* replacements for those legacy
systems (and in Europe the ADS-B link layer is Mode S/1090ES) and then
we have innovative technology like Flarm. The challenge is exactly how
all the different parts fits together and what the most important
threats to address for each pilots own situation.

And we can't just ignore legacy technology (like TCAS) for scenarios
where it is important--some of the silliest comments I've seen are
things along the line of dismissing "transponders as old technology"--
they have an important role to fill, especially with that TCAS
compatibility.

The discussion on "universal" collision avoidance technology starts
and ends with there is just no such thing. There are products that
combine different technology (like PowerFLARM) but a full solution
there would still takes multiple products, will not be "low cost" and
such an approach is going to not be justified for most gliders.

BTW that is one reason I worry about blanket national/federal
regulations for any of this stuff and much prefer to see local
voluntary adoption of appropriate technology for these scenarios.
Where that does not happen then consider mandating use but I'd hate to
see that pushed out nationally. e.g. if needed because voluntary
adoption fails I could support putting a transponder TMZ around a busy
mixed airliner/glider location or mandating Flarm in busy contests.
But I'd hate to see national ...

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If ATC are filtering out the transponder returns from gliders to avoid
screen clutter, then there is no point in gliders carrying these
expensive, power hungry and difficult to service bits of kit!

No they filter by altitude band, by assigned controller, etc. And as
I've pointed out in this thread before the TCAS in the airliners keep
working regardless of what the controller sees.



Generally I am happy with the UK situation where Commercial Air
Traffic flies under IFR in Class A to D airspace and gliders fly VFR
in Class G. This keeps me separated from the airliners. Problem is
that low cost carriers such as Ryanair are increasing flying into
minor regional airfields and creating a demand for more and more
controlled airspace. We are being squeezed into what's left, with a
greater risk of mid-air collisions with GA and military aircraft that
are also largely forced to use the same airspace.

If a low cost/low power collision alert device can be developed, I
would welcome it, especially if it gives me more access to Class D
airspace.

Yes and that device will look and smell like a transponder. If not
what kind of device do you think it will be that can interoperate with
SSR radar and TCAS etc. or be a link in future for 1090ES? I don't see
anybody making something significantly cheaper than a Trig TT21 or
similar Transponder? I don't know how Trig and others keep the costs
down on such small volumes as they are.

The Americans seem to be forcing Mode S transponders on the whole
World purely because of problems around Reno Nevada!

The Americans are doing nothing to you. Ryanair maybe.



The original poster in this thread sort of suggested that because of
an alleged near miss between a Ryanair jet and a glider near
Frankfurt, all gliders should carry transponders and that is
irresponsible not to do so. While I would not like to be responsible
for bringing down a passenger jet, there are other procedural and
technical ways of addressing this almost infinitesimally small risk.
The vast majority of glider mid-air collisions are with other gliders
and light GA aircraft, which transponders don't help with.

Derek C