Hi,

I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.

How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?

I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?

Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.

The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?

Thanks,

Paul Remde

On Wednesday, June 30, 2021 at 10:12:10 AM UTC-6, Paul Remde wrote:
> Hi,
>
> I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
>
> How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
>
> I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
>
> Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
>
> The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT.. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
>
> Thanks,
>
> Paul Remde

Hi Paul - I have the Power-FLARM Core installed (updated to the latest FW earlier this year) and run a Mode-C transponder only w/o any issues.

Uli
'AS'

There are quiet a few gliders and tow planes with mode C only.
It is possible to set most displays to only give a short audio alert for mode C instead of distracting alarm. As such I do not recommend completely disabling it.
Incidentally, I just found out that mode C PCAS is not enabled yet in powerflarm Fusion.

Ramy

On Wednesday, June 30, 2021 at 10:04:36 AM UTC-7, AS wrote:
> On Wednesday, June 30, 2021 at 10:12:10 AM UTC-6, Paul Remde wrote:
> > Hi,
> >
> > I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
> >
> > How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
> >
> > I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
> >
> > Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
> >
> > The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem.. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
> >
> > Thanks,
> >
> > Paul Remde
> Hi Paul - I have the Power-FLARM Core installed (updated to the latest FW earlier this year) and run a Mode-C transponder only w/o any issues.
>
> Uli
> 'AS'

On 6/30/21 11:04 AM, AS wrote:
> On Wednesday, June 30, 2021 at 10:12:10 AM UTC-6, Paul Remde wrote:
>> Hi,
>>
>> I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
>>
>> How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
>>
>> I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
>>
>> Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
>>
>> The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
>>
>> Thanks,
>>
>> Paul Remde
>
> Hi Paul - I have the Power-FLARM Core installed (updated to the latest FW earlier this year) and run a Mode-C transponder only w/o any issues.
>
> Uli
> 'AS'
>

Mee too, using aggressive filtering on Mode C. There's plenty of
Cessna's buzzing around below 10K feet, some of which have mode c only.
Mode C allows heavy iron with TCAS to see you, so it provides
considerable benefit.

Dave

> It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?

The mandate is kind of weird, as it's not really a mandate. It's simply an airspace restriction without active authorization. Planes affected by the mandate and not equipped with ADSB cannot fly in:

* Class A, B, and C airspace;
* Class E airspace at or above 10,000 feet msl, excluding airspace at and below 2,500 feet agl;
* Within 30 nautical miles of a Class B primary airport (the Mode C veil);
* Above the ceiling and within the lateral boundaries of Class B or Class C airspace up to 10,000 feet;
* Class E airspace over the Gulf of Mexico, at and above 3,000 feet msl, within 12 nm of the U.S. coast.

unless they contact ATC prior to entry into the airspace.

Good breakdown here: https://www.aopa.org/go-fly/aircraft-and-ownership/ads-b/where-is-ads-b-out-required#:~:text=The%20FAA%20requires%20ADS-B%20Out%20capability%20in%20the,airspace%20up%20to%2010%2C000%20feet%3B%20More%20items...%20

The takeaway is that many people still do not have ADSB, but I have no notion of how big "many" is. I personally know a pilot who flies a Mode-C equipped plane and has no intention of getting ADSB.

On Wednesday, June 30, 2021 at 11:12:10 AM UTC-5, Paul Remde wrote:
> Hi,
>
> I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
>
> How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
>
> I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
>
> Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
>
> The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT.. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
>
> Thanks,
>
> Paul Remde

Paul,

I initially had that problem with our PowerFlarmPortable and the ADSB installed last winter. The fix was to move the PowerFlarm ADSB antenna where it could get a stronger signal from the transponder antenna. According to Flarm Technologies, the Flarm expects to see its own transponder signal strongly, and if it does it doesn't issue the alarm. Seems to me the system would be more fool proof if it checked the ICAO IDs instead. We are now flying with Mode C enabled on the Flarm with not problems.

Where I'm flying there are a fair number of aircraft flying around with mode C only. I think it is wise to keep it ON and fix the Flarm issue.

Rich L.

On Thursday, July 1, 2021 at 6:34:25 AM UTC-7, richali...@gmail.com wrote:
> On Wednesday, June 30, 2021 at 11:12:10 AM UTC-5, Paul Remde wrote:
> > Hi,
> >
> > I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
> >
> > How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
> >
> > I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
> >
> > Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
> >
> > The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem.. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
> >
> > Thanks,
> >
> > Paul Remde
> Paul,
>
> I initially had that problem with our PowerFlarmPortable and the ADSB installed last winter. The fix was to move the PowerFlarm ADSB antenna where it could get a stronger signal from the transponder antenna. According to Flarm Technologies, the Flarm expects to see its own transponder signal strongly, and if it does it doesn't issue the alarm. Seems to me the system would be more fool proof if it checked the ICAO IDs instead. We are now flying with Mode C enabled on the Flarm with not problems.
>
> Where I'm flying there are a fair number of aircraft flying around with mode C only. I think it is wise to keep it ON and fix the Flarm issue.
>
> Rich L.
How do I change my Mode C transponder filtering to "Aggressine"? The FLARM website recomends this but povides no instructions. My current config file contains the following:
$PFLAC,S,MODEC,1
$PFLAC,S,OWNMODEC,0
$PFLAC,S,PCASCALIBRATION,30
$PFLAC,S,XPDR,1
$PFLAC,S,MODESALT,0

Dan C.

On Monday, July 5, 2021 at 11:36:35 AM UTC-4, colto...@gmail.com wrote:
> On Thursday, July 1, 2021 at 6:34:25 AM UTC-7, richali...@gmail.com wrote:
> > On Wednesday, June 30, 2021 at 11:12:10 AM UTC-5, Paul Remde wrote:
> > > Hi,
> > >
> > > I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
> > >
> > > How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
> > >
> > > I suppose there are aircraft without electrical systems (J3 Cubs, etc..) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
> > >
> > > Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
> > >
> > > The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful.. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
> > >
> > > Thanks,
> > >
> > > Paul Remde
> > Paul,
> >
> > I initially had that problem with our PowerFlarmPortable and the ADSB installed last winter. The fix was to move the PowerFlarm ADSB antenna where it could get a stronger signal from the transponder antenna. According to Flarm Technologies, the Flarm expects to see its own transponder signal strongly, and if it does it doesn't issue the alarm. Seems to me the system would be more fool proof if it checked the ICAO IDs instead. We are now flying with Mode C enabled on the Flarm with not problems.
> >
> > Where I'm flying there are a fair number of aircraft flying around with mode C only. I think it is wise to keep it ON and fix the Flarm issue.
> >
> > Rich L.
> How do I change my Mode C transponder filtering to "Aggressine"? The FLARM website recomends this but povides no instructions. My current config file contains the following:
> $PFLAC,S,MODEC,1
> $PFLAC,S,OWNMODEC,0
> $PFLAC,S,PCASCALIBRATION,30
> $PFLAC,S,XPDR,1
> $PFLAC,S,MODESALT,0
>
> Dan C.

Here's a commented version. # lines are comments, starting with $ is instructions. You are set correctly for aggressive Mode C.

# own Mode C signal filtering (to eliminate your own xpdr)
# 0=aggressive (use w/ Mode C Xpdr), 1=normal (no Xpdr or Mode S)
$PFLAC,S,OWNMODEC,0

On Monday, July 5, 2021 at 9:39:54 AM UTC-7, Dan Daly wrote:
> On Monday, July 5, 2021 at 11:36:35 AM UTC-4, colto...@gmail.com wrote:
> > On Thursday, July 1, 2021 at 6:34:25 AM UTC-7, richali...@gmail.com wrote:
> > > On Wednesday, June 30, 2021 at 11:12:10 AM UTC-5, Paul Remde wrote:
> > > > Hi,
> > > >
> > > > I have a question or 2 that are related to PowerFLARM and Mode C and would love some feedback from U.S. glider pilots.
> > > >
> > > > How many aircraft are there in the USA now that are Mode C only (not Mode S and not ADS-B OUT)? I'm not looking for actual numbers, just a feeling as to whether it is none or few or many. It is my understanding that all aircraft in the USA are FAA mandated now to have ADS-B OUT now (except gliders and small aircraft without electrical systems like J3 Cubs). Is that correct?
> > > >
> > > > I suppose there are aircraft without electrical systems (J3 Cubs, etc.) that are exempt from the need to have a transponder at all, but only a few of them are likely to be Mode C only - right?
> > > >
> > > > Likewise, how many gliders in the USA are Mode C only (not Mode S and not ADS-B OUT)? I'm sure there are some, but my guess is that there aren't too many.
> > > >
> > > > The reason I ask is that some PowerFLARM Core users have (for years) had issues with the PowerFLARM Core seeing their own glider and thinking it is traffic - giving annoying warnings that are distracting and not helpful. I have 2 customers right now that have Mode S transponders, but not ADS-B OUT. Some gliders with Mode S and ADS-B 1090 OUT are seeing the same problem. They have verified that the Mode S ID in their transponder matches the Mode S ID entered into their PowerFLARM Core. One of them found that if he turns off Mode C warnings, the issue goes away. My fear until now has been that turning off Mode C warnings would reduce safety - because you wouldn't be warned of gliders and aircraft that are Mode C only. But since most small aircraft must have ADS-B OUT now - I'm thinking that it may be OK to turn off Mode C warnings. What do you think?
> > > >
> > > > Thanks,
> > > >
> > > > Paul Remde
> > > Paul,
> > >
> > > I initially had that problem with our PowerFlarmPortable and the ADSB installed last winter. The fix was to move the PowerFlarm ADSB antenna where it could get a stronger signal from the transponder antenna. According to Flarm Technologies, the Flarm expects to see its own transponder signal strongly, and if it does it doesn't issue the alarm. Seems to me the system would be more fool proof if it checked the ICAO IDs instead. We are now flying with Mode C enabled on the Flarm with not problems.
> > >
> > > Where I'm flying there are a fair number of aircraft flying around with mode C only. I think it is wise to keep it ON and fix the Flarm issue.
> > >
> > > Rich L.
> > How do I change my Mode C transponder filtering to "Aggressine"? The FLARM website recomends this but povides no instructions. My current config file contains the following:
> > $PFLAC,S,MODEC,1
> > $PFLAC,S,OWNMODEC,0
> > $PFLAC,S,PCASCALIBRATION,30
> > $PFLAC,S,XPDR,1
> > $PFLAC,S,MODESALT,0
> >
> > Dan C.
> Here's a commented version. # lines are comments, starting with $ is instructions. You are set correctly for aggressive Mode C.
>
> # own Mode C signal filtering (to eliminate your own xpdr)
> # 0=aggressive (use w/ Mode C Xpdr), 1=normal (no Xpdr or Mode S)
> $PFLAC,S,OWNMODEC,0
Thanks Dan D.

I am now thinking that the issue I am having is that the Transponder antenna placement is poor. FLARM antennas are in front of instrument cluster in nose of glider and transponder antenna placement is behind cockpit near flood beneath all the control linkages and other mechanisms. FLARM website lists antenna placement as the other main issue to look for.

FLARM web site says: "If the above items do not help and it's strictly necessary to enable Mode-C processing, it may help to move the 1090 MHz receiver antenna of PowerFLARM into line-of-sight of the own transponder antenna. If the antennas are shielded from each other, e.g. by being on different sides of the aircraft (top vs. bottom), PowerFLARM may think that it's another aircraft because the signal is too weak. Just make sure to always keep at least 30 cm between the antennas."

Dan C.