At 05:01 21 December 2015, wrote:

SNIP
2. The other question is whether Stealth mode reduces safety. OK,
it may,but the real question is by how much? My own opinion is
that it's a very small amount but who really knows?

Chip Bearden
ASW 24 "JB"
U.S.A.

If you have read my other posts on other threads you will realise
that it is by no means a "small" amount but that is not the main
issue.

As part of my enquiry into a mandate stealth mode for competitions
in the UK I communicated with Dr Urban Mäder. Below is what I
learned

"I have been in touch with Dr Urban Mäder, CTO at Flarm. He has
informed me that if Stealth mode is set on any Flarm unit there is a
degredation of the data which that unit transmits to all other FLARM
units. Specifically:

1. The range at which the Stealth mode set unit is detected is
significantly reduced
2. Important information useful for situational awareness is not
transmitted by a unit in Stealth Mode
3. If a Flarm unit is set to stealth mode it effects all other FLARM
units irrespective of their setting."

This is from FLARM itself, and they should know just how much.
They very sensibly DO NOT recommended the use of stealth mode.

You might say why should I care if competition pilots in the USA
bang into each other? I do care but that is not the issue. Setting
stealth mode effects all other units, whether they are set to stealth
mode or not. Competition pilots do not operate in protected
airspace, they share it with all sorts of other users in GA and the
military, who may use FLARM and who may not be aware that their
situational awareness is reduced. They expect the service they get
from FLARM to be normal.
Can you really justify degrading the safety for pilots who may not
have any involvement or knowledge of gliding competition rules, for
any reason, or by any amount? I would be very surprised if you
could.
We cannot uninvent FLARM, we are stuck with what it is. The only
logical move is to accept that it will provide information that it was
not intended to. If everyone has FLARM it is still a level playing field,
the only people who miss out are those who do not.

Note: In the UK GA and the Royal Air Force are fitting FLARM to their
aircraft for the specific purpose of avoiding gliders. I accept that
our airspace may be more "crowded"