Notable Power Flarm saves - Is it 'worth it'?

On Wednesday, May 2, 2018 at 9:23:29 PM UTC-4, Tom BravoMike wrote:
If it's all about software, why can't we have software using the ADS-B transmission (more universal, stronger ergo better visible) to provide us, glider pilots, with the information (visual/acoustic) equal to that produced by FLARM.

I'm pretty sure that it is not 'all about software'. The two other 'biggies' are radio frequency bandwidth (limited) and the rate at which 3-D positions need to be broadcast. Position transmission rate must be limited to avoid saturation of the available bandwidth. To calculate collision avoidance between gliders (that are sharing a thermal), 3-D position broadcasts need to be very frequent, much more frequent than the rate needed for collision avoidance between powered aircraft with nominal separation.

I doubt that ADS-B out transmits frequent enough position reports to compute collision avoidance between gliders. Gliders frequently fly close to other gliders.

So you might ask, 'how come Powerflarm has enough bandwidth to do collision avoidance between proximate aircraft and ADS-B does not?' Part of the answer (I guess) is that Powerflarm uses lower transmission power (so the signal does not travel as far), and there are far fewer Powerflarm transmitters in range of other Powerflarm transmitters, than the number of ADS-B transmitters talking to each other in a Bravo airspace. Another guess is that a Powerflarm transmission is smaller than an ADS-B transmission.

ADS-B transmission is not encrypted, so if anyone would like to try to build Flarm like collision avoidance on top of ADS-B, there is nothing stopping you. I'd love to see that happen, but I'd not under-estimate the obstacles, and I would certainly not delay installing Powerflarm while waiting for something new to come on line.

On Wednesday, May 2, 2018 at 8:04:16 PM UTC-4, wrote:
I may also have to request a new Airworthiness Certificate, moving my glider from Standard to Experimental ...

Surely you're joking? And if not, how is that possible?

On Wednesday, May 2, 2018 at 6:23:29 PM UTC-7, Tom BravoMike wrote:
At the most basic level FLARM is transmitting GPS data and looking at other FLARM units GPS data.... the antennas are not directional etc. It's all about software and focus on the glider community and making the traffic warnings usable/reducing false positives and providing the NMEA based data integration with glider traffic displays and glider flight computers... nothing those other systems can do. (...)

Thank you for taking your time to clarify it to me. You are right, I have not flown in a FLARM equipped glider yet. But I find this your statement very important and revealing to me: "It's all about software and focus on the glider community". So the questions that bothers me all the time is: with the ADS-B becoming so common and mandatory for most aircraft, why should I have two transmitting systems on board (FLARM and a transponder - think about price and power usage). If it's all about software, why can't we have software using the ADS-B transmission (more universal, stronger ergo better visible) to provide us, glider pilots, with the information (visual/acoustic) equal to that produced by FLARM.

Let me make it clear: I am for the safety, visibility, awareness etc. I have a Microair Mode C Transponder and the ATD-300 Traffic Watch working beautifully, and I know it's not enough. I'm not against the idea behind FLARM and I bow down before the guys who invented and implemented it - but now it's the NextGen and ADS-B era - let's adapt to it! If a FLARM device appears on the market with the added ADS-B-Out feature, I'll be among the first to order, ready to invest in it whatever is necessary and justified.

Thanks for equipping with a transponder... that's actually a huge help near airliners, fast jets, military traffic etc. and while within SSR coverage it makes your aircraft visible via TIS-B to properly equipped aircraft (that confusingly need to have ADS-B In *and* Out...remember by complexity comment about ADS-B earlier).

PowerFLARM (with the ADS-B In option, which almost all the units in the USA have) *does* receive ADS-B 1090ES and provide much of the same capabilities as a PowerFLARM-PowerFLARM system. Unfortunately it only receivers 1090ES and not UAT, and not ADS-R or TIS-B services, even if your glider has ADS-B Out to make it a ADS-R or TIS-B Client.... unfortunate European legacy there for where the ADS-B technology in PowerFLARM came from-hopefully FLARM will address in future. But even if all that worked... you can't properly receive ADS-R or TIS-B services unless you have a TABS or 2020 Compliant ADS-B Out system. (See comment earlier about complexity...)

For 2020 Compliant ADS-B Out in a certified glider today you are looking at: Trig TT22 (~$1,900) and TN70 (~$1,900) plus install costs.

For 2020 Complaint ADS-B Out in an experimental glider today you are looking at: Trig TT22 (~$1,900) and TN72 (~$350)

You can also use the TT22 and TN72 and do TABS in the type certified glider, that gets you visibility to other ADS-B in traffic and TIS-B and ADS-R client status, but not visibility to over ADS-B out to ATC and no post-January 1 2020 ADS-B Out airspace privileges. And that's ADS-B out only... can be a great thing for visibility to say GA traffic that increasingly has ADS-B In but not say TCAS the airliners and fast jets have. But to do fully featured Dual-link ADS-B In in a glider today you need a Stratus or Stratux box and a suitable display like Foreflight (my favorite...) today there is no way to integrate that with other glider flight displays... and by then you really risk having too much junk in the cockpit distracting the pilot. There is just no single perfect collision avoidance/awareness system for gliders in the USA. On the other hand we don't need to see more fatal mid-air collisions involving gliders... so we have to do the best we can and pick the technology or combination that works best. Perfect is the enemy of good..... doing nothing because we don't have a perfect systems avaialble is not a good option.

ADS-B has benefits in dense GA environments but it's the most complex and expensive to install. The starting point for glider pilots concerned about airliners, fast jets and military traffic is to equip with a transponder (Mode C is fine). Please talk to the military folks to see what their aircraft are equipped with and if they or ATC can see transponder and how much it will help. For folks mostly concerned about other gliders and towplanes the answer is PowerFLARM but you need multiple community adoption in the local area.

If both "fast jets, airliners, military" and "gliders and tow planes" are concerns then it unfortunately takes both a transponder and PowerFLARM. But it's worth remembering those are usually the first choices, not ADS-B Out and/or In.

The leading edge of ADS-B Out adoption in gliders are folks who already own a suitable Trig transponder and who can install a TN72 GPS Source at relatively low additional cost, and/or who have post January 1 2020 regulatory concerns such as needing to fly in Class A airspace or above Class B/C airspace but below 10,000' and so who will require 2020 Compliant ADS-B Out equipped gliders. Folks who do own a Trig transponder probably should consider adding at least a TN72 at their next annual.

And while Mode C is fine to keep using, any new transponder today should be a Trig TT22 as it provides most ADS-B Out options, and if installing now I'd also install the ~$350 TN72 GPS for 2020 Complaint ADS-B Out in an experimental glider or TABS in a type certified glider... that adds ADS-B Out benefits for a relatively small increase in cost... and while wiring up the transponder you might as well install the TN72.

BTW PowerFLARM (with the ADS-B option) also includes a PCAS capability, so the same PCAS capability as in your ATD-300 for transponder equipped threat aircraft with no 1090ES Out... if the threat has 1090ES Out you get a precise target.

---

And yes all this is the technology side of stuff, yes folks need their head outside the cockpit, and it's my experience that pilots who are safety conscious enough to equip with this stuff are already pretty concerned about traffic and careful about looking outside, and PowerFLARM (and PCAS like your ATD-300) are good at reminding them to do that. And lots of other things can be done to understand traffic risks, develop ops and ATC procedures to try to reduce risks, etc.

On Wednesday, May 2, 2018 at 7:57:16 PM UTC-7, son_of_flubber wrote:
On Wednesday, May 2, 2018 at 9:23:29 PM UTC-4, Tom BravoMike wrote:
If it's all about software, why can't we have software using the ADS-B transmission (more universal, stronger ergo better visible) to provide us, glider pilots, with the information (visual/acoustic) equal to that produced by FLARM.

I'm pretty sure that it is not 'all about software'. The two other 'biggies' are radio frequency bandwidth (limited) and the rate at which 3-D positions need to be broadcast. Position transmission rate must be limited to avoid saturation of the available bandwidth. To calculate collision avoidance between gliders (that are sharing a thermal), 3-D position broadcasts need to be very frequent, much more frequent than the rate needed for collision avoidance between powered aircraft with nominal separation.

I doubt that ADS-B out transmits frequent enough position reports to compute collision avoidance between gliders. Gliders frequently fly close to other gliders.

Nope. ADS-B Out at ~2 Hz, actually transmits at at higher rate than FLARM. It really is mostly "just" about software. And I'm not saying that to minimize stuff, it's actually very hard to do this well. FLARM has invested a lot of work there to get this far.

So you might ask, 'how come Powerflarm has enough bandwidth to do collision avoidance between proximate aircraft and ADS-B does not?' Part of the answer (I guess) is that Powerflarm uses lower transmission power (so the signal does not travel as far), and there are far fewer Powerflarm transmitters in range of other Powerflarm transmitters, than the number of ADS-B transmitters talking to each other in a Bravo airspace. Another guess is that a Powerflarm transmission is smaller than an ADS-B transmission.

ADS-B has the bandwidth. It's transmitting away all those packers already. That is not the issue... and PowerFLARM itself today works on top of 1090ES In signals just fine.

One ADS-B issue is, as it has always been, the cost of doing ADS-B Out. Both the cost of the transmitter and suitable GPS source.... especially if you want that source to be 2020 Complaint. So doing a software layer similar to FLARM, with as much focus on needs of glider pilots, on top of ADS-B Out needs ADS-B Out adoption in gliders, and then somebody to develop software and build out an ecosystem similar to FLARM and do things like sign up OEMs and integration partners, and... oh my. Just ain't likely to happen is it?

ADS-B transmission is not encrypted, so if anyone would like to try to build Flarm like collision avoidance on top of ADS-B, there is nothing stopping you. I'd love to see that happen, but I'd not under-estimate the obstacles, and I would certainly not delay installing PoweFlarm while waiting for something new to come on line.

Yes, indeed, its all unencrypted, which ends up being an separate issue... for another day. Although spending a few $k on RTCA spec docs will help things go faster. After that it will only take a small fortune of developer time and lots of effort. And if you are doing ADS-B smart stuff the money is not to be made in the glider market.. it's in the GA market today, and maybe large drone/UAV markets. So I'd *really* not hold my breath.

"Surely you're joking? And if not, how is that possible?"

Nope. No joke. As to "how," you go to FAA dot Gov and download FAA Form 8130-6 "Application for US Airworthiness Certificate" and fill it out. Your aircraft must be in compliance with all Airworthiness Directives. You need an inspection by a "Certificated Mechanic," possibly an inspection by an "FAA Designee" or FAA Inspector. There may be a Flight Test period (generally five hours TT for Phase 1). Your Operating Limitations will be spelled out as part of the new certificate and will place certain restrictions on use of the aircraft. A yearly Program Letter must be filed with the local FSDO.

Going from Standard Category to Experimental is relatively simple. Trying to go from Experimental to Standard is nearly impossible, so this decision should be carefully considered, as it may affect the value of your aircraft. However, many gliders operate under "Experimental" limitations without much in the way of restrictions. It is just that certain things are easier to accomplish mechanically with an Experimental Certificate. In this case, as Darryl states:

"For 2020 Compliant ADS-B Out in a certified glider today you are looking at: Trig TT22 (~$1,900) and TN70 (~$1,900) plus install costs.

For 2020 Compliant ADS-B Out in an experimental glider today you are looking at: Trig TT22 (~$1,900) and TN72 (~$350)"

The price point of the TN70 at $1,900 vs $350 for the TN72 is what is driving my decision.

"Thanks for equipping with a transponder..."

Darryl- I have been flying with a Becker 3401/5401 Transponder/ Control Unit for over 9 years. It didn't pass re certification this year due to an undetermined problem (spurious altitude deviations according to the test equipment). Rather than throw money (possibly LOTS of money) at an old piece of equipment, I chose to go with a new Trig TT22. As to adding the TN72, that will depend on whether to go to Experimental Category. For ADS-B In, I am using PowerFlarm and my LXNav S80 display.

If I can determine the problem with the Becker, I will probably fix it and sell it, or possibly sell it "as is" with the caveat that it needs diagnosis, repair and a new approval.

On Wednesday, May 2, 2018 at 10:24:27 PM UTC-7, wrote:
"Thanks for equipping with a transponder..."

Darryl- I have been flying with a Becker 3401/5401 Transponder/ Control Unit for over 9 years. It didn't pass re certification this year due to an undetermined problem (spurious altitude deviations according to the test equipment). Rather than throw money (possibly LOTS of money) at an old piece of equipment, I chose to go with a new Trig TT22. As to adding the TN72, that will depend on whether to go to Experimental Category. For ADS-B In, I am using PowerFlarm and my LXNav S80 display.

If I can determine the problem with the Becker, I will probably fix it and sell it, or possibly sell it "as is" with the caveat that it needs diagnosis, repair and a new approval.

You can always add a TN72, just on a type certified glider it can only do SIL=1/TABS.

On the Becker transponder... the encoder and cabling is always suspect there. Ideally have a technician test it with a know good encoder and cabling on a bench... but it's probably not worth much not working. I've seen used working Becker ATC4401 transponders selling for ~$600 with encoder.... that can be a nice deal for folks who have older gliders and want to add a Mode C transponder.

On Wednesday, May 2, 2018 at 11:39:37 PM UTC-4, Darryl Ramm wrote:
^ BTW PowerFLARM (with the ADS-B option) also includes a PCAS capability

Darryl, can you explain that further, for those of us who are dazed and stupefied when confronted with the FAA's alphabet soup? AFAIK, PF does not transmit anything that the ATC system receives, so how can it give you collision warnings for non-FLARM aircraft, other than the warning about the presence of a transmitting transponder nearby?

Also, you say a cheap used mode C transponder is a good addition to a glider. Can you explain further what that will get you? E.g., will ATC still see you after 2020? Will PowerFLARM devices sense your mode C transponder transmissions? Will the collision-avoidance equipment on airliners detect you, now and in the future?

Off topic, but...

On 5/2/2018 9:59 PM, Darryl Ramm wrote:

One ADS-B issue is, as it has always been, the cost of doing ADS-B Out. Both the cost of the transmitter and suitable GPS source.... especially if you want that source to be 2020 Complaint.

Yeah, and I just bought a WAAS GPS from Amazon
https://www.amazon.com/Dual-Electronics-XGPS150A-Multipurpose-Augmentation/dp/B006M49G80/ref=sr_1_3?s=electronics&ie=UTF8&qid=1525361200&sr =1-3&keywords=waas+gps
for $78.58.Â* I can use that to provide a good signal to my iPad if I
choose to use it in my glider for powered repositioning flights and
using Garmin Pilot software.

Seems to me that the price of a "suitable" GPS source has more to do
with paperwork (TSO) than with technology.
--
Dan, 5J

Air Avionics has recently announced an "Air Traffic" box that combines
Flarm
with GPS suitable for ADS-B Out, at least in EASA land.

https://www.air-avionics.com/?page_id=253