A pilot reported a traffic position error when his garmin 750 ads-right displayed traffic at 1 o'clo...

Attributes
ACN	1094261
Time
Date	201305
Local Time Of Day	1201-1800
Place
Locale Reference	PCT.TRACON
State Reference	VA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	None
Component
Aircraft Component	Navigational Equipment and Processing
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 55 Flight Crew Total 12000 Flight Crew Type 3000
Events
Anomaly	Aircraft Equipment Problem Less Severe
Miss Distance	Horizontal 0 Vertical 1000

Narrative:

During a VMC cross country from ZZZ to I66 and at a position ~7 NM southwest of the mrb airport at 2;200' MSL traffic was observed approaching from 11 o'clock high on the avidyne TAS-600 displayed on both the avidyne mhd and the garmin gtn-750. The traffic was acquired visually at 11 o'clock. This traffic was not displayed in the same position by the garmin gdl-88 on the garmin GNS-430W. Instead; the traffic from the ads-right was displayed incorrectly at 1 o'clock. The altitude deltas matched. Download of ads-B data confirmed the TAS position but did not substantiate the ads-B position. It appears that the ads-B uplink is providing spurious traffic information and this incorrect information could cause a midair collision in an aircraft not also equipped with TAS or TCAS. The discrepancy was photographed using a 3MP camera setting and the discrepant positions are clearly visible. Checking with the FAA via rand revealed confirmation of the TAS traffic track and no explanation for the ads-right traffic position. It appears that ads-right is defective. Similar occurrences are noted about 5% of the time; two prior ASRS reports on this discrepancy have been filed.

Original NASA ASRS Text

Title: A pilot reported a traffic position error when his Garmin 750 ADS-R displayed traffic at 1 o'clock; but it was acquired visually at 11 o'clock and corresponded with a Avidyne TAS-600 target.

Narrative: During a VMC Cross Country from ZZZ to I66 and at a position ~7 NM southwest of the MRB Airport at 2;200' MSL traffic was observed approaching from 11 o'clock high on the Avidyne TAS-600 displayed on both the Avidyne MHD and the Garmin GTN-750. The traffic was acquired visually at 11 o'clock. This traffic was not displayed in the same position by the Garmin GDL-88 on the Garmin GNS-430W. Instead; the traffic from the ADS-R was displayed incorrectly at 1 o'clock. The altitude deltas matched. Download of ADS-B data confirmed the TAS position but did not substantiate the ADS-B position. It appears that the ADS-B uplink is providing spurious traffic information and this incorrect information could cause a midair collision in an aircraft not also equipped with TAS or TCAS. The discrepancy was photographed using a 3MP camera setting and the discrepant positions are clearly visible. Checking with the FAA via RAND revealed confirmation of the TAS traffic track and no explanation for the ADS-R traffic position. It appears that ADS-R is defective. Similar occurrences are noted about 5% of the time; two prior ASRS reports on this discrepancy have been filed.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A pilot reported a traffic position error when his garmin 750 ads-right displayed traffic at 1 o'clock; but it was acquired visually at 11 o'clock and corresponded with a avidyne TAS-600 target.