Sean, one thought. If you do nothing (except, of course, look) as the unit progresses up the alerting scale, it is telling you it is increasingly likely that you WILL collide (your current speed and altitude are partly causing it; since you can't the sure the other lady or gentleman will change, you should (IMHO) (you both should, hopefully using the rules of the road as a guide)). If I can't quickly pick up the target, I aggressively maneuver to avoid it (generally by changing altitude; if it's higher, I dive, if lower, I pull up, energy permitting). If on the ridge, it becomes more interesting...

I am aware that the OSTIV Training and Safety Panel (TSP) is working on recommended actions on receipt of flarm alerts, and multiple versions have been proposed (I've seen 3)... but, there isn't agreement on final text, as far as I know.

Finally, the warnings - from the latest PF manual (3.40):
"FLARM-warnings are issued in accordance with the time remaining to a possible collision, not the geometric distance between the aircraft. The first warning is typically issued between 19 and 25 seconds in advance to the calculated possible collision with aircraft or obstacle (time to impact); the second is issued 14 to 18 seconds in advance, and the third 6 to 8 seconds in advance. Warnings are sustained as long as the threat remains as calculated. Depending upon the prediction, the threat may be downgraded or deleted. Warnings are selective, i.e. they are only issued if the calculation detects a high probability of a collision in the immediate future." page 5 of manual.

2D