On Thursday, November 1, 2012 5:45:02 AM UTC-7, Don Johnstone wrote:
At 02:05 01 November 2012, Ramy wrote:

Don, can you back up your claim that Flarm was designed mainly for wave

flying by providing some reference?

Also,can you share with us your actual experience flying with Flarm?



Ramy



The original FLARM was conceived to assist pilots in detecting difficult to

see gliders, particulary in wave where the relative movement is small, the

closure rate is slow and the track of another glider cannot easily be

detected by observing the way it is pointing.

I fly a Discus fitted with FLARM and an LX8000. The LX8000 linked to the

FLARM provides a "radar" display on the moving map. I have found the system

to be useful when flying in wave, I have found it to be less useful, if not

distracting in thermals. On a short 3 mile ridge with 20 or 30 gliders it

is positively lethal.

I do not use the LX8000 display at all when flying a ridge or in thermals..

I have used it when flying in wave, however I still feel the time spent

looking at the LX display and trying to make sense of it would be better

spent looking out.

The most scary thing, even using just the clock lights on the basic system,

is that it is misleading when flying a ridge in higher wind speeds. The

light bears no relation to the direction of the threat so I hear the bleep

and look all round. I have to say that there have been very few occasions

when the alert has sounded and I have not seen the glider causing it before

the alert sounded, lucky maybe?

Lucky, yes.

In a dozen flights I probably picked up 10-15 conflicts that I had not already determined to be a threat visually. Examples include: an LS-8 doing a zoomie from down below my nose after overtaking me from behind/below, a Discus 2 that decided to leave a thermal by cutting through the middle of the circle and across my path from above/behind, a glider a half mile abeam of me that changed to a converging course line. On top of that there were multiple cases of traffic encountered on course and gliders adjusting their circles in thermals, I found most of them immediately useful and a couple were downright sobering.

I never use the radar display in a thermal - it's not good for that and not intended for that, but it is useful in making you aware when a glider you might not have seen is now in your general vicinity. Mis-using the radar display by going heads-down in close quarters is not grounds for a sweeping criticism of the device. You could make the same criticism of an airspeed indicator - staring at it until you fly into an obstacle would be dangerous and dumb, but isn't a reason to remove the instrument from your panel.

I recall the same as UH - that Flarm was developed for Alpine flying, but not especially for wave - (which is a small portion of overall flight time). I always understood Flarm was targeted at a general set of glider collision threat scenarios - all of which would be exacerbated by the traffic funneling that mountain flying of every form tends to generate. I expect Urs could clarify.

9B