Narrative:

Departed ont and proceeded on assigned heading of 255 degrees and 4000 ft. Upon reaching 4000 ft; I was assigned a heading of 210 degrees for traffic. I was then assigned a heading of 230 degrees to join V186 as per our original clearance. About 30-60 seconds later; I was queried by ATC as to why I was deviating from the original assigned heading of 210 degrees. I stated to ATC that I was assigned heading 230 degrees to intercept V186 and that I repeated the assignment and was not corrected. I was then told that I was not supposed to have deviated from the original 210 degree heading. At this point I was confused as to what was happening since I fully believed I was complying with ATC instructions. I did turn back to a heading of 210 degrees as directed. The controller also asked why I would turn to the right when a left turn would be required to intercept V186. I observed the 'active' leg on the onboard garmin 530 GPS which directed me to turn right to intercept the airway. Thus; the controller was saying a left turn was required to join and according to the onboard GPS; a right turn seemed appropriate. Based on this conflict; I decided to revert to my #2 navigation to establish position on the airway. I then established myself on V186 and was then issued a phone number to call upon landing to the ATC area manager. I believe that I made every effort to comply with ATC instructions. I repeated virtually every assignment given and was not corrected. If a deviation occurred; it was by no means intentional. I did not observe a traffic conflict. However; upon talking to ATC by phone; they advised me that they had lost separation with another aircraft. No other conflicts or deviations occurred for the remainder of the flight. Every effort was made to comply and/or rectify the situation. However; I cannot say for sure what caused the incident. At this point; I can only be even more cautious about ATC assignments and positional awareness. Contributing factors might include: high pilot workload (departure process); pilot familiarity to area; possible equipment programming error (GNS530); ATC not clarifying/correcting readback of assignments. Use of secondary navigation system could be helpful in situational awareness and will be utilized henceforth. Company was notified and an irregularity report filed.

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Original NASA ASRS Text

Title: AN APPARENTLY MISPROGRAMMED GPS CONTRIBUTES TO AN UNWITTING TRACK DEVIATION FOLLOWED BY A REPRIMAND FROM ATC FOR A SMA PLT.

Narrative: DEPARTED ONT AND PROCEEDED ON ASSIGNED HDG OF 255 DEGS AND 4000 FT. UPON REACHING 4000 FT; I WAS ASSIGNED A HDG OF 210 DEGS FOR TFC. I WAS THEN ASSIGNED A HDG OF 230 DEGS TO JOIN V186 AS PER OUR ORIGINAL CLRNC. ABOUT 30-60 SECONDS LATER; I WAS QUERIED BY ATC AS TO WHY I WAS DEVIATING FROM THE ORIGINAL ASSIGNED HDG OF 210 DEGS. I STATED TO ATC THAT I WAS ASSIGNED HDG 230 DEGS TO INTERCEPT V186 AND THAT I REPEATED THE ASSIGNMENT AND WAS NOT CORRECTED. I WAS THEN TOLD THAT I WAS NOT SUPPOSED TO HAVE DEVIATED FROM THE ORIGINAL 210 DEG HDG. AT THIS POINT I WAS CONFUSED AS TO WHAT WAS HAPPENING SINCE I FULLY BELIEVED I WAS COMPLYING WITH ATC INSTRUCTIONS. I DID TURN BACK TO A HDG OF 210 DEGS AS DIRECTED. THE CTLR ALSO ASKED WHY I WOULD TURN TO THE R WHEN A L TURN WOULD BE REQUIRED TO INTERCEPT V186. I OBSERVED THE 'ACTIVE' LEG ON THE ONBOARD GARMIN 530 GPS WHICH DIRECTED ME TO TURN R TO INTERCEPT THE AIRWAY. THUS; THE CTLR WAS SAYING A L TURN WAS REQUIRED TO JOIN AND ACCORDING TO THE ONBOARD GPS; A R TURN SEEMED APPROPRIATE. BASED ON THIS CONFLICT; I DECIDED TO REVERT TO MY #2 NAV TO ESTABLISH POS ON THE AIRWAY. I THEN ESTABLISHED MYSELF ON V186 AND WAS THEN ISSUED A PHONE NUMBER TO CALL UPON LNDG TO THE ATC AREA MGR. I BELIEVE THAT I MADE EVERY EFFORT TO COMPLY WITH ATC INSTRUCTIONS. I REPEATED VIRTUALLY EVERY ASSIGNMENT GIVEN AND WAS NOT CORRECTED. IF A DEV OCCURRED; IT WAS BY NO MEANS INTENTIONAL. I DID NOT OBSERVE A TFC CONFLICT. HOWEVER; UPON TALKING TO ATC BY PHONE; THEY ADVISED ME THAT THEY HAD LOST SEPARATION WITH ANOTHER ACFT. NO OTHER CONFLICTS OR DEVS OCCURRED FOR THE REMAINDER OF THE FLT. EVERY EFFORT WAS MADE TO COMPLY AND/OR RECTIFY THE SITUATION. HOWEVER; I CANNOT SAY FOR SURE WHAT CAUSED THE INCIDENT. AT THIS POINT; I CAN ONLY BE EVEN MORE CAUTIOUS ABOUT ATC ASSIGNMENTS AND POSITIONAL AWARENESS. CONTRIBUTING FACTORS MIGHT INCLUDE: HIGH PLT WORKLOAD (DEP PROCESS); PLT FAMILIARITY TO AREA; POSSIBLE EQUIP PROGRAMMING ERROR (GNS530); ATC NOT CLARIFYING/CORRECTING READBACK OF ASSIGNMENTS. USE OF SECONDARY NAV SYS COULD BE HELPFUL IN SITUATIONAL AWARENESS AND WILL BE UTILIZED HENCEFORTH. COMPANY WAS NOTIFIED AND AN IRREGULARITY RPT FILED.

Data retrieved from NASA's ASRS site as of May 2009 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.