Cessna pilot using both tis-B and TAS for traffic avoidance reports erroneous target information fro...

Narrative:

My cessna is nearly unique at this point because it has both a garmin gdl-88 supplying a garmin GNS-430 (tis-B) and an avidyne TAS-600 (TAS) displaying on both a garmin gtn-750 and an avidyne multihazard display (mhd). [Southwest of cmh descending through 2500 feet]; the tis-B produced a TA for traffic inside of a mile and 200 feet below me at 1:30 o'clock and on an intersecting course. No traffic was seen out the window at the 1:30 position. The TAS did not see any traffic at 1:30 o'clock but did locate traffic inside of a mile and going away (same vector as the tis-B) at the same time as the TA and at the same altitude (200 feet below me) but at the 7:30 o'clock position. This traffic was confirmed by visual sighting. It appears that the tis-B misplotted the location of the traffic and generated a fallacious TA. TAS data appears to have been correct. This circumstance repeated itself about 2 minutes later without a TA with tis-B traffic at 2 o'clock and a mile and a half at 500' below my altitude. No traffic was seen at the tis-B report location but new traffic was confirmed at the same altitude and vector on TAS at 8 o'clock and a mile and a half. It appears that the tis-B uplink provided incorrect locations for ads-B traffic that was simultaneously painted by TAS and visually confirmed at the TAS reported altitude; position and vector. Tis-B was incorrect and; in reduced visibility created a high accident potential situation because a turn away from the tis-B traffic would have resulted in closure with the actual TAS traffic and the development of a potential mid-air collision scenario.

Original NASA ASRS Text

Title: Cessna pilot using both TIS-B and TAS for traffic avoidance reports erroneous target information from the TIS-B. The TIS indicated traffic at 1:30 coming toward the reporter and TAS indicated traffic at 7:30 going away on the same heading. The TAS traffic was visually confirmed.

Narrative: My Cessna is nearly unique at this point because it has both a Garmin GDL-88 supplying a Garmin GNS-430 (TIS-B) and an Avidyne TAS-600 (TAS) displaying on both a Garmin GTN-750 and an Avidyne MultiHazard Display (MHD). [Southwest of CMH descending through 2500 feet]; the TIS-B produced a TA for traffic inside of a mile and 200 feet below me at 1:30 o'clock and on an intersecting course. No traffic was seen out the window at the 1:30 position. The TAS did not see any traffic at 1:30 o'clock but did locate traffic inside of a mile and going away (same vector as the TIS-B) at the same time as the TA and at the same altitude (200 feet below me) but at the 7:30 o'clock position. This traffic was confirmed by visual sighting. It appears that the TIS-B misplotted the location of the traffic and generated a fallacious TA. TAS data appears to have been correct. This circumstance repeated itself about 2 minutes later without a TA with TIS-B traffic at 2 o'clock and a mile and a half at 500' below my altitude. No traffic was seen at the TIS-B report location but new traffic was confirmed at the same altitude and vector on TAS at 8 o'clock and a mile and a half. It appears that the TIS-B uplink provided incorrect locations for ADS-B traffic that was simultaneously painted by TAS and visually confirmed at the TAS reported altitude; position and vector. TIS-B was incorrect and; in reduced visibility created a high accident potential situation because a turn away from the TIS-B traffic would have resulted in closure with the actual TAS traffic and the development of a potential mid-air collision scenario.

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.

Attributes
ACN	1086090
Time
Date	201304
Local Time Of Day	1201-1800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Direct
Flight Plan	None
Component
Aircraft Component	Traffic Collision Avoidance System (TCAS)
Person 1
Qualification	Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 82 Flight Crew Total 11800 Flight Crew Type 4500
Events
Anomaly	Aircraft Equipment Problem Critical
Miss Distance	Horizontal 2500 Vertical 200

Cessna pilot using both tis-B and TAS for traffic avoidance reports erroneous target information from the tis-B. The tis indicated traffic at 1:30 coming toward the reporter and TAS indicated traffic at 7:30 going away on the same heading. The TAS traffic was visually confirmed.