On Monday, January 4, 2016 at 11:01:47 AM UTC-8, XC wrote:

Is there really a benefit of tracking a glider on your FLARM display for 4 minutes? Take a situation where there are 4 other gliders in your proximity. Keeping track of them all continuously with FLARM is a lot of heads down time. A lot of the gliders are more than 1000 feet difference in altitude and are no collision threat. Having all that displayed clutters the important info so is really only of tactical benefit.


I think 4 minutes was meant as part of a general visual scan rather than continuously fixating on the display. A scan that returns to the display within about 1/2 the lead time you'd expect to have for a target seems reasonable. If you only scan at the maximum lead-time a target can sneak in pretty close before you pick it up.

Four minutes of situational awareness lead time means scanning every minute or two. One minute of lead time means scanning every 30 seconds and 10 seconds of lead time would require you to have your head down pretty much continuously if you were concerned about nasty surprises. If you want to just wait for a target to become a collision threat and react to the collision alarm then by definition maintaining situational awareness to prevent conflicts is not part of your approach.

Because the "wait for the alarm to go off" makes some of us uncomfortable - the OODA loop is just too long with Flarm alarms in some cases - we prefer to keep track of aircraft in a bigger envelope before they get to alarm mode. Doing that is easier if you don't have to keep going back to the display to see what's new. For instance, I scan more frequently running cloud streets and convergence lines - particularly if I know there is traffic likely ahead because of an out and back course configuration, etc. I know that converging traffic can come up in a hurry and I want to be ahead of it if I can.

9B