FLARM in Stealth Mode at US 15M/Standard Nationals - Loved It!

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 . . .

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

On Saturday, August 8, 2015 at 8:31:38 PM UTC-4, Andy Blackburn wrote:
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.

25 seconds. Stealth mode doesn't reduce the range at which the anti-collision alerts happen. What appears to be true is that you won't see the targets on tactical display until the warning happens.

Evan Ludeman / T8

Hmmm...

Not according to the Flarm Dataport Specification 7.03 released on July 30, 2015 that says no target data is put onto the serial port for targets above 2 km in distance. At 17,000' and 110 kts IAS for two head-to-head targets that's a hair over 10 seconds.

9B

On Saturday, August 8, 2015 at 10:41:24 PM UTC-4, Andy Blackburn wrote:
Hmmm...

Not according to the Flarm Dataport Specification 7.03 released on July 30, 2015 that says no target data is put onto the serial port for targets above 2 km in distance. At 17,000' and 110 kts IAS for two head-to-head targets that's a hair over 10 seconds.

9B

I don't have that document (is it on the web anywhere?), but it sounds like you are looking at the description of the $PFLAA sentence (traffic data).

-Evan

It's the PRIV command spec for Stealth Mode

On Saturday, August 8, 2015 at 11:58:09 PM UTC-4, Andy Blackburn wrote:
It's the PRIV command spec for Stealth Mode

I was promised a copy of the dataport spec that I still haven't received.

I hope this is a documentation screw up. There's no earthly reason to do it this way.

best,
Evan

On Saturday, August 8, 2015 at 7:41:24 PM UTC-7, Andy Blackburn wrote:
Hmmm...

Not according to the Flarm Dataport Specification 7.03 released on July 30, 2015 that says no target data is put onto the serial port for targets above 2 km in distance. At 17,000' and 110 kts IAS for two head-to-head targets that's a hair over 10 seconds.

9B

Without the target data on the serial port, you will not get a voice enunciation of that target from your third party device.

True. In Stealth mode you also won't get speed, track and climb rate info and the altitude will be dithered. That makes it hard for your display device to do anything other than 1mi / 1000 ft traffic alerts - which is what LX does with Stealth off anyway.

I'll have to look up whether collision alarms are calculated and passed to the serial port some how for high closing rate threats outside the 2km limit for stealth target blanking. Even if that's teue it's not at all clear that an alarm would come with any traffic display, since no exceptions are mentioned in the spec for blanking this info outside 2km and not every target on a reciprocal heading generates a collision warning sonita possible for converging traffic to get down to 2km and change course towards you. Flarm extrapolates, but it doesn't anticipate maneuvering. My setup is 8-12 km for head-on, so normally I'd pick up a potential threat a lot further out from a visual scan, voice annunciation not withstanding. I think of gliders making a 180 at a turnpoint as a classic scenario. They're invisible, then they're 10+ seconds away and you have an alarm (but maybe not a target on the display until they close within 2km?).

9B

Andy,
Check out FIRMWARE RELEASE NOTES FLARM 6.02 Firmware. As I read it, for any determined threat even outside 2km and +/- 300m vertically you should get an alarm, relative position, relative altitude, climb rate,track and speed but no ID.
XC