Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 55; Flight Crew Total 12000; Flight Crew Type 3000
Troubleshooting; Situational Awareness; Distraction
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Equipment / Tooling
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.
The reporter stated that he believes his TAS-600 to be problem free so far but he has had several flights where the ADS-R traffic reported by the Garmin 750 was inaccurately positioned.
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.