On Wednesday, November 25, 2015 at 10:45:05 AM UTC-8, James Metcalfe wrote:
At 21:44 24 November 2015, Andy Blackburn wrote:
... Since you've owned several I guess it's safe to say there's
more benefit
than downside. ...

Sorry to disappoint: I haven't owned any. These were 3 different
units in 2 club-owned two-seaters, flown in the French Alps
where Flarm was mandated by all the clubs in the area.

On balance Flarm *may* indeed be beneficial. But the purpose
of my post was to point out that there *are* significant
downsides. Pilots should be aware of these and avoid indulging
in gratuitously risky practices, under the illusion that Flarm will
protect them. They should also avoid making vigorous evasive
manoeuvres in response to Flarm alone: it is imperative to see
the threat before making anything other than a gentle
manoeuvre, perhaps a small wing-waggle to aid conspicuity.
This applies not only to threats from behind / blind spots. I am
sure that vigorous manoeuvres (unexpected by the other pilot,
who could see that the situation was under control) will result in
collisions - or perhaps already have ("such a shame ... and they
both had Flarm")

Finally I should say that my initial expectation of Flarm (and
BTW I love the technology!) was that it would significantly
reduce effective lookout - I'm afraid that's just my view of
human nature. That may or may not have happened - how could
I tell? However, as soon as I flew with Flarm, I was shocked to
discover what crazy manoeuvres other pilots were making,
which I had not experienced before, and which disappeared
when I next flew without Flarm.

... I guess it depends on how you define [false alarm] ...

No, I didn't mean warnings given about empty space! I meant
collision warnings about a glider opposite me in the thermal, or
established in another, distant, thermal, or 500+ feet above or
below, etc. In other words, when no collision risk existed or
developed, regardless of how 'competitive' I felt.

J.

I am curious about your experience with the interface. Did you just have the BF display, or was the Flarm also displaying targets on a moving map?

I have not had any Flarm warnings that would have saved a midair (3 years with it now). But I have always had Flarm targets displayed on the glide computer moving map, and so nearly always see them long before they could be considered a threat. Two times in those three years I have gotten an unexpected warning, though not close enough to require action to avoid collision. I use those events as a learning experience to see how I need to change my scans and operations, so that they do not happen again.

From this I conclude that the situational awareness, far away from an potential conflict, is more valuable for preventing potential conflicts in the first place than the actual warning facility.

Countless times that Flarm has identified and displayed glider within a km of me that I had not seen and might never have seen.