GTX345 and missing traffic targets

The ramblings of our community of aviators.

Moderators: Rick, Lance Murray

User avatar
Boatguy
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Russ
Aircraft: DA40NG
Registration: N454M
Airport: O69

Posts: 361
Joined: Mon Jan 22, 2018 4:48 am
Has thanked: 135 times
Been thanked: 255 times

GTX345 and missing traffic targets

Post by Boatguy »

Garmin issued the attached Service Bulletin for the GTX345 last October. I tried to have my plane updated, but the avionics shop told me the update had to come from Diamond. Garmin has issued the software update and Diamond has received it. However, Diamond does not consider this a "safety of flight" issue because the FAA did not issue an AD so they have not bothered to issue an update for Diamond aircraft.

Late last year I had an incident where crossing traffic was identified by ATC (SR22) and crossed 500' directly below me, but never appeared on my display. At the time I was about 45nm NE of KSFO. I attributed the incident to this bug but could not confirm it with the necessary information from Garmin. Today I received the response below from Garmin.

The bottom line is that if you fly in an area where there are more than 200 airplanes within 150nm of your airplane (i.e., a 300nm diameter circle), which is the norm in any major metro area, your traffic display is not showing you all targets. Targets include airplane to airplane ADSB, ADSB relayed through a ground tower, or primary radar targets relayed through a ground tower. A crop duster 100nm away from you picked up as a primary radar target counts towards the 200. Since this is a problem with the 345, not the G1000, even if you're looking at traffic in Foreflight, if the data is coming from a GTX345, you won't see all the targets.

We may have "state of the art" avionics, but we're still "see and avoid" until Diamond issues a software update.

***************************
It was brought to our attention from one of our Sales Managers that you have been waiting on a response for over two weeks to a question regarding what “in range” means with respect to the Service Bulletin 1981 Rev. A GTX 345 ADS-B software version 3.13.

The software fix outlined in Service Bulletin 1981 Rev. A (GTX 345 ADS-B software version 3.13) changed the method in which the GTX 345 tracks traffic targets. In v3.13, the GTX 345 will perform range filtering on received traffic targets when its traffic database reaches its capacity (200 traffic targets). It maintains the range of all traffic targets currently in the traffic database and when new traffic targets are received, and the traffic database has reached capacity, it calculates the range of the new traffic target to the ownship and then searches the traffic database for a target that is farther away from the ownship than the new traffic target. If it finds a traffic target that is further away, it replaces the further target with the new traffic target. The traffic database will maintain traffic targets within 150 nm of the ownship. Prior to v3.13, the 201st traffic target would not be displayed regardless of range from the ownship.

Garmin has reviewed this issue in accordance with our internal policies and procedures. As a result of this internal review, Garmin issued a Service Bulletin to the field to educate operators on the issue and how to correct it with updated software. However, in accordance with FAA AC 90-114A Chg 1, Garmin has not identified this as a safety of flight issue.

******************************

The Garmin explanation is still either not quite clear, or the software has yet another problem (note "further away", rather than "farthest away") and I will see further information from Garmin.
GTX345R SB 1981A_ASDN.pdf
(74.54 KiB) Downloaded 17 times
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
FIRST NAME: Rich
Aircraft: DA40
Registration: N40XE
Airport: S39

Posts: 2393
Joined: Mon Aug 30, 2010 12:40 pm
Has thanked: 64 times
Been thanked: 356 times

Re: GTX345 and missing traffic targets

Post by Rich »

Boatguy wrote:
Mon Mar 30, 2020 10:04 pm

A crop duster 100nm away from you picked up as a primary radar target counts towards the 200.
It's my understanding you won't see Primary or Mode A being retransmitted. This from the Stratus 3 manual:

Mode A transponders and primary radar targets detected by the FAA are not included in rebroadcasted traffic reports.

This exactly matches with what I observe (and don't observe) in my area.
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
User avatar
Boatguy
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Russ
Aircraft: DA40NG
Registration: N454M
Airport: O69

Posts: 361
Joined: Mon Jan 22, 2018 4:48 am
Has thanked: 135 times
Been thanked: 255 times

Re: GTX345 and missing traffic targets

Post by Boatguy »

OK. No crop dusters without transponders.
User avatar
mdieter
3 Diamonds Member
3 Diamonds Member
FIRST NAME: Mark
Aircraft: DA40
Registration: N43LM
Airport: KROC

Posts: 123
Joined: Wed Jul 17, 2013 7:03 pm
Has thanked: 44 times
Been thanked: 19 times

Re: GTX345 and missing traffic targets

Post by mdieter »

For what it's worth, I tried to have the GTX345R software updated on two occasions. In the end we ended up reverting the software to the original version. It is not a simple upgrade when a G1000 is involved.

On the second attempt we got the transponder updated to the latest version via a laptop and USB connection, but then the G1000 would not communicate with the transponder. After more digging, I found that there is a software version manifest that the G1000 keeps that contains validated software versions. The new GTW345 software version was not listed, therefore the G1000 won't communicate with the transponder. It thinks the transponder is invalid. I'm guessing the manifest file has to come from Garmin as a G1000 update. No idea if Garmin has created a manifest file for our aircraft with the proper software versions. My avionics guy didn't seem to know about it.

Anyone else had any experiences?
Mark
N43LM
DA40.1047
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
FIRST NAME: Rich
Aircraft: DA40
Registration: N40XE
Airport: S39

Posts: 2393
Joined: Mon Aug 30, 2010 12:40 pm
Has thanked: 64 times
Been thanked: 356 times

Re: GTX345 and missing traffic targets

Post by Rich »

Boatguy wrote:
Mon Mar 30, 2020 10:04 pm
Late last year I had an incident where crossing traffic was identified by ATC (SR22) and crossed 500' directly below me, but never appeared on my display.
Out of curiosity, do you know if this SR22 was an ADS-B emitter or would it need to have been relayed as TIS-B?
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
User avatar
Boatguy
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Russ
Aircraft: DA40NG
Registration: N454M
Airport: O69

Posts: 361
Joined: Mon Jan 22, 2018 4:48 am
Has thanked: 135 times
Been thanked: 255 times

Re: GTX345 and missing traffic targets

Post by Boatguy »

No way to know for sure, but it was about 15nm from the KSFO Mode C veil on a heading to be inside the veil within about 4min, on an IFR flight plan, two weeks before the ADSB mandate took effect. Seems pretty likely.
User avatar
Charles K
3 Diamonds Member
3 Diamonds Member
FIRST NAME: Charles
Aircraft: DA40
Registration: N5WU
Airport: KCCR

Posts: 149
Joined: Mon Feb 21, 2011 7:46 pm
Has thanked: 5 times
Been thanked: 22 times

Re: GTX345 and missing traffic targets

Post by Charles K »

When one of us is involved in a mid-air (hopefully never) because software in our GTX-345R had a bug that was known - but classified as not 'safety of flight' - the lawsuit will forever change what they consider safety of flight.
Charles
KCCR Based
N5WU - 2004 G1000 DA40 40.400, GTX345R ADS-B
IFR and ME Rated - Advanced Ground Instructor Rated
User avatar
Boatguy
4 Diamonds Member
4 Diamonds Member
FIRST NAME: Russ
Aircraft: DA40NG
Registration: N454M
Airport: O69

Posts: 361
Joined: Mon Jan 22, 2018 4:48 am
Has thanked: 135 times
Been thanked: 255 times

Re: GTX345 and missing traffic targets

Post by Boatguy »

mdieter wrote:
Tue Mar 31, 2020 5:51 pm
For what it's worth, I tried to have the GTX345R software updated on two occasions. In the end we ended up reverting the software to the original version. It is not a simple upgrade when a G1000 is involved.

On the second attempt we got the transponder updated to the latest version via a laptop and USB connection, but then the G1000 would not communicate with the transponder. After more digging, I found that there is a software version manifest that the G1000 keeps that contains validated software versions. The new GTW345 software version was not listed, therefore the G1000 won't communicate with the transponder. It thinks the transponder is invalid. I'm guessing the manifest file has to come from Garmin as a G1000 update. No idea if Garmin has created a manifest file for our aircraft with the proper software versions. My avionics guy didn't seem to know about it.
That's why my avionics shop told me they couldn't do the update.

Based on my conversations with Garmin and Diamond, the software has been available to Diamond since last year, but apparently they can't distribute it without approval from Transport Canada and they have not made that request because they've been focused on getting approvals for new aircraft.

I suggest every Diamond owner sign up with Garmin for updates on their avionics as you'll never get this information from Diamond. At least with the information from Garmin we know we're not seeing all the traffic.
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
FIRST NAME: Rich
Aircraft: DA40
Registration: N40XE
Airport: S39

Posts: 2393
Joined: Mon Aug 30, 2010 12:40 pm
Has thanked: 64 times
Been thanked: 356 times

Re: GTX345 and missing traffic targets

Post by Rich »

Boatguy wrote:
Tue Mar 31, 2020 7:22 pm
No way to know for sure, but it was about 15nm from the KSFO Mode C veil on a heading to be inside the veil within about 4min, on an IFR flight plan, two weeks before the ADSB mandate took effect. Seems pretty likely.
Likely, but not assured. I used to fly out of KPAE, which lurks within the SEA Mode C veil. It was a common occurrence for the tower to admonish: "I'm not picking up your transponder". Response: "Uh, OK, let me recycle it". Tower: "OK, receiving now". There are many pilots who routinely fly around with transponders turned off (or on standby) unless they think they need it.

This really is a sidebar to the issue you raise, which is legitimate. The simplest algorithm would be if the new target is closer than the furthest target in the database, toss the furthest target and add the new one. That may be what they meant to say. I could think of some situations where this might be overly simplistic. But it's far batter than the current situation.

It also seems like 150 nm is an awfully large distance to be concerned with. It would take a closing speed of 18,000 knots for such a target to be a problem in the next 30 seconds.
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
User avatar
Lance Murray
5 Diamonds Member
5 Diamonds Member
FIRST NAME: Lance
Aircraft: DA40

Posts: 1049
Joined: Tue Jul 06, 2010 11:25 pm
Has thanked: 2 times
Been thanked: 72 times

Re: GTX345 and missing traffic targets

Post by Lance Murray »

You are still see and avoid. No matter if you have TCAS II, ADS-B, TAS, whatever. See and avoid is the rule when VFR.
Post Reply