Case Study Near Mid Air Glider and C421 - Benefits of PowerFlarm and Transponders

With all the discussion about FLARM, ADS-B and the Pros/Cons, I thought the time is right to bring some facts into the discussion. Last September I had a near mid air with a C421. Since I had recently equipped over the previous winter with a Mode S transponder (Trig T22), I was curious whether: 1) It was working... 2)Did the FAA use my target to call traffic.

Turned out the answer was yes! to both questions. I filed a near mid report to the FAA which resulted in two interviews and this radar ARTCC video with ATC controller audio. I think you'll find it quite interesting.

https://dl.dropbox.com/s/k8ph9wogyif...1 TT.wmv?dl=0

The FAA statement incorrectly identified the twin as a King Air with only (my visual esimate)
horizontal separation estimate of 500ft.

https://dl.dropbox.com/s/e6gvhn6dybx...FAA.pdf?dl =0

According to the radar we passed by at 10,000msl zero vertical and 1300ft horizontal. By pure luck and good scanning technique, I sighted the C421 15 seconds before crossing. PowerFlarm PCAS went off 2-3 seconds later. PowerFlarm would have got my attention if my visual scanning had failed me. No evasive action occurred on my part.

When you listen to the audio/video you will see a red "CA" meaning Conflict Alert going off for the controller. This went off at 33 seconds. If FAA modified their ADS-B ERAM software, they could send out ADS-B packets for aircraft on a collision course. PowerFlarm would then have given plenty of warning without cluttering the bandwidth of ADS-B with unnecessary information.. This recommendation was made to the FSDO FAA representative who interviewed me.

I am complete agreement with Darryl Ramm's analysis of this whole transponder (Mode S) PowerFlarm recommendation. They complement each other quite well... and this is the best solution for the time being. As he has said, the whole ADS-B thing with TABS looming in the near future is in a state of flux. I wouldn't be surprised to see combined Mode-S/ADS-B transponders coming onto the market in abundance within 3 or 4 years.

In case you are wondering ... I did NOT recommend in my response to the FAA NPRM immediately equipage of gliders with transponders. Instead, utilize good airspace practices, training and a short "wait and see" for more affordable equipment to become available. However, if you have the money... by all means equip with a transponder and PowerFlarm.

Walter Rogers "WX" Discus 2A

I forgot one more thing... my analysis of the radar ATC video/audio:

https://dl.dropbox.com/s/xbxo0k4zlzo...s is.txt?dl=0

Walt Rogers WX

At 07:24 20 January 2016, WaltWX wrote:
I forgot one more thing... my analysis of the radar ATC video/audio:

https://dl.dropbox.com/s/xbxo0k4zlzo...s is.txt?dl=0

Walt Rogers WX

Wow. To the lay man this looks just like the controller was waiting for and
watching a collision happen. You were right on track and they didn't tell
the guy to turn away. What is the point of watching the screen if you do
not take action?

Were you turning all the time? If so you should have been easy to see.

On Wednesday, January 20, 2016 at 2:09:34 AM UTC-5, WaltWX wrote:
I had recently equipped over the previous winter with a Mode S transponder (Trig T22), I was curious whether: 1) It was working... 2)Did the FAA use my target to call traffic.

Turned out the answer was yes! to both questions.

I've a Trig T21. An ATC controller told me that I might be filtered/deleted from his display when circling or flying in wave due to my low ground speed.

Does your display on the radar have anything to do with the low traffic where you were flying or ATC knowledge of glider traffic in that area?

More generally, I'd like to have a better idea of when a Mode-S equipped glider is visible to ATC and when it is not visible.

On Wednesday, January 20, 2016 at 7:14:24 AM UTC-8, son_of_flubber wrote:
On Wednesday, January 20, 2016 at 2:09:34 AM UTC-5, WaltWX wrote:
I had recently equipped over the previous winter with a Mode S transponder (Trig T22), I was curious whether: 1) It was working... 2)Did the FAA use my target to call traffic.

Turned out the answer was yes! to both questions.

I've a Trig T21. An ATC controller told me that I might be filtered/deleted from his display when circling or flying in wave due to my low ground speed.

Does your display on the radar have anything to do with the low traffic where you were flying or ATC knowledge of glider traffic in that area?

More generally, I'd like to have a better idea of when a Mode-S equipped glider is visible to ATC and when it is not visible.

The controller was misunderstanding that you have a transponder, or badly misunderstanding how radar works. The 'velocity-doppler filter" is very important and is on primary radar not SSR/transponder returns.

Transponders are the backbone of the ATC surveillance systems, aircraft with them just don't disappear because they slow down.

For gliders without transponders you damn well bet you can disappear from primary radar, especially if the radar needs the velocity-doppler filter turned up to reduce noise, that might be to help filter ou general ground scatter, cars on freeways/highways, wind generator farms, etc. Talking to your local ATC radar facility and seeing what they can and can't see on primary radar is usually interesting, and frequently an eye opener for folks in busy areas to get a damn transponder.

A Mode S or C transponder is "visible" to ATC when you are flying within SSR coverage and the transponder is turned on and correctly working.

son_of_flubber wrote on 1/20/2016 7:14 AM:
I've a Trig T21. An ATC controller told me that I might be
filtered/deleted from his display when circling or flying in wave due
to my low ground speed.

I know primary radar signals might be filtered based on speed to remove
ground clutter, but never heard that would be done to a transponder
equipped aircraft. Gliders in wave aren't the only thing that can move
slowly - consider helicopters and balloons.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

Eric, I take offense to that statement, helicopters are as fast as gliders, in fact they have a high cruise speed! ) Having said that, one day I flew above LA class Bravo airspace without speaking with control (above 10,000 ft). I was tuned into LA approach and could hear them telling airliners, "I think it is a helicopter, or maybe a small Cessna, but I doubt that". I think back then I still had a mode C transponder.

I have many times been parked in a glider in wave over Julian VOR speaking with ATC who had me on radar, could confirm altitude and position. I would have had nearly zero ground speed and no transponder.
Same in Owens valley, no transponder and no problem with ATC seeing me, circling or not.

I now have a mode S transponder in the glider, plus a power Flarm. Looks like to get ADS-B out I will have to get a fourth GPS.


On Wednesday, January 20, 2016 at 9:12:34 PM UTC-8, Eric Greenwell wrote:
son_of_flubber wrote on 1/20/2016 7:14 AM:
I've a Trig T21. An ATC controller told me that I might be
filtered/deleted from his display when circling or flying in wave due
to my low ground speed.

I know primary radar signals might be filtered based on speed to remove
ground clutter, but never heard that would be done to a transponder
equipped aircraft. Gliders in wave aren't the only thing that can move
slowly - consider helicopters and balloons.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

On Thursday, January 21, 2016 at 9:51:56 AM UTC+3, Jonathan St. Cloud wrote:
Eric, I take offense to that statement, helicopters are as fast as gliders, in fact they have a high cruise speed! )

Depends which helicopter. the Hughes/Schweizer/whatever 300 cruises at 160 km/h. I believe there are plenty of 300+ km glider flights done at higher average speed.

The R22 is a little faster, 90 knots or 167 km/h. I've blasted past them a few times, climbing, with both of us in ridge lift.

My only piston helicopter time is 3 hours in a Bell 47, amazing easy to fly bird, that can actually glide (very unusual for a helicopter). And comparing a piston copter to a glass glider is unfair, they should be compared to Ka-6, 1-26..etc. I believe the 300 and 22 both beat the older birds.

In the turbine machines, a bit more of the same era as glass gliders, cruise is 110 to 150 knots. Not many 200 - 400 nm mile flights in glider are in that speed range. Even in a lowly MD 500 at 64% power (top of green 89%) I would cruise at 120 knots, want to race?



On Thursday, January 21, 2016 at 2:56:45 AM UTC-8, Bruce Hoult wrote:
On Thursday, January 21, 2016 at 9:51:56 AM UTC+3, Jonathan St. Cloud wrote:
Eric, I take offense to that statement, helicopters are as fast as gliders, in fact they have a high cruise speed! )

Depends which helicopter. the Hughes/Schweizer/whatever 300 cruises at 160 km/h. I believe there are plenty of 300+ km glider flights done at higher average speed.

The R22 is a little faster, 90 knots or 167 km/h. I've blasted past them a few times, climbing, with both of us in ridge lift.

On Wednesday, January 20, 2016 at 2:09:34 AM UTC-5, WaltWX wrote:
With all the discussion about FLARM, ADS-B and the Pros/Cons, I thought the time is right to bring some facts into the discussion. Last September I had a near mid air with a C421. Since I had recently equipped over the previous winter with a Mode S transponder (Trig T22), I was curious whether: 1) It was working... 2)Did the FAA use my target to call traffic.

Turned out the answer was yes! to both questions. I filed a near mid report to the FAA which resulted in two interviews and this radar ARTCC video with ATC controller audio. I think you'll find it quite interesting.

https://dl.dropbox.com/s/k8ph9wogyif...1 TT.wmv?dl=0

The FAA statement incorrectly identified the twin as a King Air with only (my visual esimate)
horizontal separation estimate of 500ft.

https://dl.dropbox.com/s/e6gvhn6dybx...FAA.pdf?dl =0

According to the radar we passed by at 10,000msl zero vertical and 1300ft horizontal. By pure luck and good scanning technique, I sighted the C421 15 seconds before crossing. PowerFlarm PCAS went off 2-3 seconds later. PowerFlarm would have got my attention if my visual scanning had failed me. No evasive action occurred on my part.

When you listen to the audio/video you will see a red "CA" meaning Conflict Alert going off for the controller. This went off at 33 seconds. If FAA modified their ADS-B ERAM software, they could send out ADS-B packets for aircraft on a collision course. PowerFlarm would then have given plenty of warning without cluttering the bandwidth of ADS-B with unnecessary information. This recommendation was made to the FSDO FAA representative who interviewed me.

I am complete agreement with Darryl Ramm's analysis of this whole transponder (Mode S) PowerFlarm recommendation. They complement each other quite well... and this is the best solution for the time being. As he has said, the whole ADS-B thing with TABS looming in the near future is in a state of flux. I wouldn't be surprised to see combined Mode-S/ADS-B transponders coming onto the market in abundance within 3 or 4 years.

In case you are wondering ... I did NOT recommend in my response to the FAA NPRM immediately equipage of gliders with transponders. Instead, utilize good airspace practices, training and a short "wait and see" for more affordable equipment to become available. However, if you have the money... by all means equip with a transponder and PowerFlarm.

Walter Rogers "WX" Discus 2A

Wow, sorta scary watching it and listening to what ATC did/didn't say to the other aircraft.

Curious to see if anything else develops on this.

BTW, you "may" want to hide your address/contact info in the PDF.

Oh, glad to see you're still around to discuss this.