Ian,

Yes we would very much like to have your views, if you send them to me by
e-mail I will see that they reach the correct people.

Thank you for your posting.

Regards,

Bill.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Ian" wrote in message
news
On Wed, 09 Aug 2006 17:48:00 +0000, Gerhard Wesp wrote:


Ian Strachan wrote:


aircraft worldwide. A smart avionics engineer should be able to design
a special low-powered transmitter that would take an NMEA or other
output from existing GPS equipment and automatically transmit the data
on (electronic) request. This could be a practical step towards the


I'm sure most here know FLARM http://www.flarm.com/index_en.html .

While I'd not suggest it to the CAA for ATC because of it's limited
range, it is actually a step in this direction.


I have a both a Flarm and Mode C Transponder in my glider.

For those who have not flown with Flarm, I can confirm that they work
exceeding well. The major limitation is the fact that not all gliders
at our club are equipped with it.

There are some clever tricks in Flarms. The transmitters use the clock
signal from the GPS receiver to synchronize their transmissions so that
there are no "collisions". This allows a large number of Flarms to share
a limited amount of bandwidth. I think Flarm technology, coupled with a
higher power transmitter, could go a long way to making transponders
redundant.

I use the transponder on wave days. We can get clearance into a
"window" in controlled airspace, but we have to squawk. We have to talk
to ATC at the same time and we very soon know if they can't see us.
Unfortunately this has happened more often than I like, both with my own
glider and with others at our club.

The problems can be tracked down to many sources:

- Battery problems. (The most common). Even if a battery is fully
charged with healthy voltage on the ground, it does not mean that it is
capable of delivering it's rated current for the duration of a flight.
Having two is essential, but I have had two fully charged, apparently
healthy, batteries fail on the same flight. Often when a battery is under
performing, there is no clear indication - the transponder appears to be
working normally - but ATC can't see me until I swap onto the spare
battery.

- Wiring issues. Space in gliders is cramped and access to the available
space if often very difficult. It is just not possible to install heavy
cable racks and heavy connectors with wire locked retaining screws. Hence
the installations in gliders are, on average, less reliable than those in
power aircraft.

- Antenna issues. There is not much volume inside a glider to mount a
transponder antenna and things are worse for those with carbon fuselages.
Many gliders in our club have antenna mounted behind the instrument panel
which is far from ideal. Mine is mounted in the fuselage where other
gliders might have a pop-up engine. But access there is a major issue and
there is still significant shielding from the retracted under-carriage.
Those with external antenna are subject to damage during outlandings,
trailering, rigging and general ground handling.

Perhaps the biggest issue is that we have no means of testing
transponders before flight, we only find out if there is a problem when we
talk to ATC. (Here Flarm has a major advantage over the transponders. We
have receivers as well as transmitters and we can soon detect if one of
them is not working.) I would not be surprised if there are pilots flying
transponder equipped gliders, who squawk regularly in the belief that the
heavy a/c will pick them up on their warning receivers, but in actual fact
are not being seen.

I think it would be very short sighted to assume that if all gliders were
equipped with transponders that they would all be detected by ground
and/or airborne radar. If heavy aircraft are routed between the gliders
that are detected, their could be some surprises.

On the other hand, if all gliders were equipped with high power Flarms, we
would have a very useful glider/glider midair proximity warning system at
the same time as providing an indication of our presence to others.

Ian

(I would be happy to submit my opinions to the UK authorities, but I fly
in South Africa, so would they even consider it?)