GTX345 and missing traffic targets
Posted: Mon Mar 30, 2020 10:04 pm
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.
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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.
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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.
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.