On Saturday, August 8, 2015 at 4:43:49 PM UTC-7, wrote:
This is how I see it.
People are talking about situational awareness, and being able to look at your flarm scope and see where other gliders are (without climb rates etc).. Okay so, think about all the years that contests had a waiting list because they filled up, so there were a ton of gliders all flying in close proximity without flarm and they didn't have an overwhelming amount of mid-airs, pretty much because everyone was looking out the window. Now if every one has flarm with just gliders no climb rates, altitudes, or contest ids. Now people are going to be looking at their flarm scope for traffic and not looking out the window, where that guy who's flarm antenna got obstructed is, or that power traffic who doesn't use flarm is . . .


That's been hypothesized a lot, but so far the statistics don't bear it out - nor does the science.

The problem is that the human central vision that has detail and allows you to pick out a target is only 2 degrees wide - that's about two thumb widths at arms length. Even if you are looking diligently, scientific studies by NASA, the USAF and the Australian Trasport Safety Bureau (these are just the ones I've read) indicate that your odds of picking up a target that's on a collision course are less than 50/50, possibly as low as 1 in 4, depending on the scenario.

It's easy to pick up targets that AREN'T going to hit you because your peripheral vision is quite broad and designed to pick up movement (collision threats don't move until the wingtips spread apart in your field of vision in the last 2-4 seconds). Because we see a lot of non-threat targets out there, we think that our scan is pretty good. It's not - at least on when it matters the most.

Ask Ramy Yanetz about his near miss over the Sierras. Both pilots had detected the other's Flarm target. Both knew where to look. Neither ever saw the other until they were already passing (angular movement). Only a radio call between a known set of contest IDs - "TG is turning right" - kept them apart. This fact, by the way, is a reason to mandate Flarm (even in Stealth) having contest ID's available rather than hiding them - a radio call "everybody turn right!" is not so useful in in response to an urgent head-to-head alarm at your altitude. Under stealth mode (at least at western TASs) you'll have about 10 seconds to figure out who should zig and who should zag - assuming the alarm happens at max stealth range, rather than because somebody you never saw coming made a turn in your direction.

So, despite the fact that most people are trained on the 1920s doctrine of see-and-avoid, and based on that assert that looking at your Flarm display puts you at greater risk, it is quite likely that in any scenario outside thermalling with other gliders, staring at your Flarm display may be the best thing you can do to avoid running into someone. With ASD-B equipage coming in 2020, it will likely also hold true for power traffic.

No - I am not advocating everyone put their head in the cockpit 100% of the time. A healthy scan certainly is always a good idea - and especially with targets in close. Plus hawks don't carry ADS-B - yet.

9B