SV 12.0 upgrade

[kurtfly]

I upgraded my SV to version 12.0 and noticed the SV-XPNDR no longer has a GND mode. With the xpondr in AUTO it statuses on top of screen as ALT mode all the time. I have not flown with this software yet but just wondering if this is expected. I was in the hanger not in motion, the GNS-430W was still acquiring satellites. Change log has the following notes regarding the SV-XPNDR:

Improved: Since "ON" mode is almost never used in mode-S operations, and pilots using that mode likely intend to / should be in ALT, a XPNDR NOT IN ALT MODE alert is presented whenever the SV-XPNDR-26X has been in "ON" mode for >5 seconds.

Improved: Automatic switching of AIR and GROUND modes for the SV-26X-XPNDR when flying at low airspeed.

 

[Dynon]

Which version of the squat switch setting are you using under TRANSPONDER SETUP?

 

[dynonsupport]

You likely have your squat switch misconfigured. It should be "AUTO AIR/GND". If it's in another mode it will do this.

I admit that I don't fully know what will happen if it doesn't have a GPS lock, so there's a chance it's because of that too.

Finally, is your airspeed zero on the PFD? If you are messing with your pitot system this will happen too.

 

[kurtfly]

It was programed to the Automatic air mode. I did not re-check it since the upgrade. I did not connect my squat (WoW) switch to Skyview.

 

[kurtfly]

No airdata checks in progress. Ill check the transponder settings to see if they changed.

 

[kurtfly]

Today I check the Transponder Settings and confirmed it is in "AUTO AIR/GND"  I also confirmed that once the IFR GPS (GNS 430W) has acquired satellites and is ready to navigate the xponder status goes to "GND".  I flew with version 12.0 and otherwise works fine.  It automatically goes to "ALT" during takeoff roll.  After landing and before shutdown I verified the transponder status was in "GND" mode then I turned off the GNS 430W and the transponder immediately goes to "ALT" mode.  I am 99% sure it did not go into "ALT" mode at any other time except when airborne with version 11.1.  So I am not sure having the transponder in "ALT" mode while on the ground when the GPS is off or still initializing / acquiring satellites is proper???
Is this the way Dynon intends this to operate???

 

[NASA515]

The FAA changed the AIM to use "ALT" on the ground some time ago.

FAA Safety Team | Safer Skies Through Education
Updated AIM Information
Notice Number: NOTC4145

Recently a pilot informed us of changes to the Aeronautical Information Manual (AIM) concerning the use of lights and transponder while moving on the surface of an airport. This pilot learned from a Designated Pilot Examiner (DPE). Although it is your individual responsibility to stay aware of procedures in the AIM, we thought you would want to know about this particular safety initiative!

The AIM, which is available at http://www.faa.gov/air_traffic/publi.../aim/Index.htm, is updated in February and July of each year, and included in the last February change was an updated description of the “Operation Lights On” pilot safety program.

..... the use of your transponder while taxiing is recommended in paragraph 4-1-20. It says, in part,

Civil and military transponders should be turned to the “on" or normal altitude reporting position prior to moving on the airport surface to ensure the aircraft is visible to ATC surveillance systems.

After this change came out, I just selected my Xpdr to ALT and haven't changed it since.  Simple.

FWIW, I seem to be tracked on the ground, even though I fly from an un-towered airport a long ways from any known ATC radar site.  My Xpdr "R" light illuminates almost continuously on the ground.  What's more, if I recall my flight from FlightRadar24, it shows my taxi route around the airport, and even stops when I shut off my avionics equipment before I arrive at my hangar.  I thought this might be ADS-B info picked up by nearby receivers, but that doesn't explain the illuminated "R' indicator light.

Bob Bogash
RV-12
N737G

 

[dynonsupport]

We do mean for the transponder to work this way. A Mode-S transponder needs to prefer air mode any time it cannot determine it's on the ground. It was always doing this, but it sometimes said GND when it was in AIR. That's what we fixed in 12.0. So now, when you don't have GPS, and it can't tell it's on the ground, it properly says AIR.

It cannot use just airspeed to know it is on the ground. The FAA requires redundant info to be in GND mode, so both GPS and IAS must read basically zero to be on GND.

Bob,
The AIM could be clearer. AUTO is appropriate with a Mode-S. With a Mode-C, ALT is correct, but with a Mode-S, AUTO is what you want, because GND counts as ALT, but it won't reply to TCAS devices and throw off airliners on final. So you really do want to be in AUTO, not ALT. GND still replies with ALT in the data, it just doesn't respond to everyone.

 

[Schorsch]

A Mode-S transponder needs to prefer air mode any time it cannot determine it's on the ground. It was always doing this, but it sometimes said GND when it was in AIR. That's what we fixed in 12.0. So now, when you don't have GPS, and it can't tell it's on the ground, it properly says AIR.

It cannot use just airspeed to know it is on the ground. The FAA requires redundant info to be in GND mode, so both GPS and IAS must read basically zero to be on GND.

Bob,
The AIM could be clearer. AUTO is appropriate with a Mode-S. With a Mode-C, ALT is correct, but with a Mode-S, AUTO is what you want, because GND counts as ALT, but it won't reply to TCAS devices and throw off airliners on final. So you really do want to be in AUTO, not ALT. GND still replies with ALT in the data, it just doesn't respond to everyone.

I don't think it's fixed... I have mine on AUTO and today I saw my SV-XPNDR switch to GND numerous times while circling in thermals - ie in flight with IAS > 40kts and GPS ALTITUDE way high (though ground speed probably close to zero in tight circles). Can send diag. Logs if helpful

Also requesting a MAP INFO item for ALT AGL, if possible

 

[dynonsupport]

George,
We're looking into this and discussing it with the transponder team. We'll get back to you after Oshkosh.

 

[Schorsch]

I confirmed on further flights that my SV-XPNDR on setting auto atl/Gnd (air data) incorrectly squawks GND while in flight with IAS > 40kts (usually while circling). Hoping for fix soon...

 

[dynonsupport]

George,
We are looking into this. It should not switch until 30 knots, and we have verified in other installs that it does not. We have an idea what may cause this and we'll check ASAP.

 

[dynonsupport]

George,
We believe we found the issue.

The speed that the AUTO AIR/GND was changed for was only changed for light aircraft. I assume you have your aircraft type set to "glider"? We have verified that if it's set as glider, the switch occurs at 60 knots, not 30.

This is a bug that we will fix. For now, you can fix it yourself by setting your aircraft category to Light. If it's a powered glider, then the regs are not clear what you should choose, so light is just as appropriate as glider. If it's a pure sailplane then eventually you'll probably want to set it back once the issue is resolved, but these categories are not used by ATC or traffic displays currently so it's not an issue for now.

Thanks for the report.

 

[Schorsch]

Thx!!!

 

[dynonsupport]

As an FYI, it has been confirmed by our transponder experts that any aircraft with a motor should choose "light" aircraft, not a glider. Glider is for aircraft with no motor that cannot move by themselves when on the surface of an airport.

 

[Schorsch]

Then I' like to request that you make the glider's AND the light AC's "switch" speed 25 kts IAS  because 30 is a tad too high.

 

[dynonsupport]

It's actually 30 MPH, so it is 26 knots already.