Narrative:

ATC was contacted 3 mi east of abc at 2300 ft MSL with ATIS inbound. Closer in I was advised that the mode C was erratic. Both the left and right runways were in use at the time. I was then cleared for a left base entry for runway 7L and cleared #2 to land. I was too high so advised the tower that I wanted a 360 degree left to lose excess altitude and speed. The landing clearance was canceled and the turn was approved. Upon completion I was again cleared for a left base entry for runway 7L and cleared #2 to land. On base approaching the turn to final with the traffic in sight; I looked right to clear myself and saw what appeared to be a cirrus or lancair on final at my 1-2 O'clock position; converging and not moving relative to my windshield. I took evasive action and turned toward the aircraft's tail to avoid a possible midair collision. A left turn toward final would have placed my right wing in my line of sight of converging traffic and would have impaired my ability to see and avoid. It also would have violated three of the right-of-way rules; (91.112(B);(D) and (G); and in my judgement might involve a collision. In the course of this maneuver I crossed the extended runway line of runway 7L. As I neared the extended runway line of runway 7R; I could see that the subject traffic was for the right and not the left runway. At this point I turned back to my final for runway 7L and executed the touch and go. Based on my perception of the situation; I feel I did the only safe thing I could have. As a result; at no time was safe separation compromised. I acted early in the situation at a point where separation could be maintained. I had erred in my air to air distance perception. Runway separation is minimal at ZZZ.

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Original NASA ASRS Text

Title: A BL30 PLT ON A PARALLEL VFR APCH TO A CLOSELY SPACE RWY CHANGED HDG TOWARD THE OTHER RWY'S CTRLINE AVOIDING CONFLICTING TFC.

Narrative: ATC WAS CONTACTED 3 MI E OF ABC AT 2300 FT MSL WITH ATIS INBOUND. CLOSER IN I WAS ADVISED THAT THE MODE C WAS ERRATIC. BOTH THE L AND R RWYS WERE IN USE AT THE TIME. I WAS THEN CLRED FOR A L BASE ENTRY FOR RWY 7L AND CLRED #2 TO LAND. I WAS TOO HIGH SO ADVISED THE TWR THAT I WANTED A 360 DEG L TO LOSE EXCESS ALT AND SPD. THE LNDG CLRNC WAS CANCELED AND THE TURN WAS APPROVED. UPON COMPLETION I WAS AGAIN CLRED FOR A L BASE ENTRY FOR RWY 7L AND CLRED #2 TO LAND. ON BASE APCHING THE TURN TO FINAL WITH THE TFC IN SIGHT; I LOOKED R TO CLR MYSELF AND SAW WHAT APPEARED TO BE A CIRRUS OR LANCAIR ON FINAL AT MY 1-2 O'CLOCK POS; CONVERGING AND NOT MOVING RELATIVE TO MY WINDSHIELD. I TOOK EVASIVE ACTION AND TURNED TOWARD THE ACFT'S TAIL TO AVOID A POSSIBLE MIDAIR COLLISION. A L TURN TOWARD FINAL WOULD HAVE PLACED MY R WING IN MY LINE OF SIGHT OF CONVERGING TFC AND WOULD HAVE IMPAIRED MY ABILITY TO SEE AND AVOID. IT ALSO WOULD HAVE VIOLATED THREE OF THE RIGHT-OF-WAY RULES; (91.112(B);(D) AND (G); AND IN MY JUDGEMENT MIGHT INVOLVE A COLLISION. IN THE COURSE OF THIS MANEUVER I CROSSED THE EXTENDED RWY LINE OF RWY 7L. AS I NEARED THE EXTENDED RWY LINE OF RWY 7R; I COULD SEE THAT THE SUBJECT TFC WAS FOR THE R AND NOT THE L RWY. AT THIS POINT I TURNED BACK TO MY FINAL FOR RWY 7L AND EXECUTED THE TOUCH AND GO. BASED ON MY PERCEPTION OF THE SITUATION; I FEEL I DID THE ONLY SAFE THING I COULD HAVE. AS A RESULT; AT NO TIME WAS SAFE SEPARATION COMPROMISED. I ACTED EARLY IN THE SITUATION AT A POINT WHERE SEPARATION COULD BE MAINTAINED. I HAD ERRED IN MY AIR TO AIR DISTANCE PERCEPTION. RWY SEPARATION IS MINIMAL AT ZZZ.

Data retrieved from NASA's ASRS site as of January 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.