Ramy wrote:

One would wish that one of the local US manufactures of glider avionics
or an entrepreneur would have try to license flarm in US. If it is
possible to manufacture and sell TPAS like equipments in the US without
liability concerns, it should be possible to sell Flarms.

This is my belief, also, and perhaps the TPAS manufacturers are the ones
to approach about this. They might be able to convince the FLARM folk
that they could manufacture and sell the units without any liability for
FLARM, or develop one their own. A unit for North America wouldn't need
to be compatible with units in other countries.

I think the biggest problem is disinterest in the US community. In
preparation for a presentation on FLARM at the 2005 SSA convention, I
contacted a number of pilots about potential interest in it. I thought
the Minden pilots would be very excited about it because of the White
Mountains issues, but there was almost no interest in it. I was stunned.

I now think the potential for collision with another glider is widely
perceived (rightly or wrongly) as so low, it's not worth the effort or
cost to use something like FLARM. One way to reduce the cost would be a
FLARM with an IGC secure recorder, so the additional cost of the FLARM
capability is, say, less than $200 (I don't know if that is possible).
Still, since so many pilots already have a secure recorder, it might
take years for a significant number to be in use.

Perhaps a simpler, cheaper, "proximity" alert unit would be more
acceptable in North America. It wouldn't be completely passive, but
would broadcast a periodic weak signal with an ID code that can be
detected a mile or two away. It would receive signals from other units
and estimate their distance by the signal strength (no GPS). TPAS
manufacturers could easily convert their current designs (like the Zaon
MRX) just by fitting a different RF "front end". The box, power supply,
displays, logic, etc would remain the same. This would make it much
cheaper for them to develop and manufacture than a FLARM style unit.

It wouldn't be as effective as a FLARM, but if it were available for
less than $500, there might be a market for it. The Zaon MRX unit, for
example, already has an altimeter function in it, so the altitude could
be broadcast along with the ID code, allowing display of the relative
altitudes of the two gliders.

In the ideal world, this detection capability would be an "add-on" to a
company's standard TPAS unit, allowing detection of transponder equipped
aircraft AND aircraft with just the dual TPAS.

It just occurred to me the reason the TPAS unit manufacturers don't seem
to have a liability issue is their units only alert based on proximity,
and not on predicted flight path. If this is true, perhaps a modified
FLARM could be sold in North America by FLARM folks or a licensed
dealer/manufacturer.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org