Narrative:

On visual approach to manassas, handed off from dulles approach, reported northeast of manassas city inbound for landing on west side of field. Local controller advised unable west side (runway 16R) then cleared to fly left base runway 16L, report 2 mi. Later, but prior to 2 mi report, controller reissued instructions, but this time specified #2 to follow other aircraft to runway 16R. Other aircraft reported traffic not in sight, continuing downwind. Controller apparently then confused call signs or position of aircraft in pattern, or both. Aircraft on extended downwind turned to base, head-on to my flight path, same altitude. Controller issued 360 degree turn to a third aircraft and cleared my callsign to land runway 16R, but apparently meaning other aircraft, and the other aircraft turned final. Runway 16R. I reported 2 mi, turned final for runway 16L and so stated in report. Controller was clearly rattled/confused about traffic. Landing was uneventful. After clear of active runway. Controller turned me over to ground for extended taxi back to west ramp. Controller failed to maintain awareness of traffic in pattern, causing potential midair collision.

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Original NASA ASRS Text

Title: ATCT HEF LCL CTLR CONFUSES A C172 IFR ON A VISUAL APCH WITH ANOTHER INBOUND ACFT CAUSING A POTENTIAL MIDAIR COLLISION.

Narrative: ON VISUAL APCH TO MANASSAS, HANDED OFF FROM DULLES APCH, RPTED NE OF MANASSAS CITY INBOUND FOR LNDG ON W SIDE OF FIELD. LCL CTLR ADVISED UNABLE W SIDE (RWY 16R) THEN CLRED TO FLY L BASE RWY 16L, RPT 2 MI. LATER, BUT PRIOR TO 2 MI RPT, CTLR REISSUED INSTRUCTIONS, BUT THIS TIME SPECIFIED #2 TO FOLLOW OTHER ACFT TO RWY 16R. OTHER ACFT RPTED TFC NOT IN SIGHT, CONTINUING DOWNWIND. CTLR APPARENTLY THEN CONFUSED CALL SIGNS OR POS OF ACFT IN PATTERN, OR BOTH. ACFT ON EXTENDED DOWNWIND TURNED TO BASE, HEAD-ON TO MY FLT PATH, SAME ALT. CTLR ISSUED 360 DEG TURN TO A THIRD ACFT AND CLRED MY CALLSIGN TO LAND RWY 16R, BUT APPARENTLY MEANING OTHER ACFT, AND THE OTHER ACFT TURNED FINAL. RWY 16R. I RPTED 2 MI, TURNED FINAL FOR RWY 16L AND SO STATED IN RPT. CTLR WAS CLRLY RATTLED/CONFUSED ABOUT TFC. LNDG WAS UNEVENTFUL. AFTER CLR OF ACTIVE RWY. CTLR TURNED ME OVER TO GND FOR EXTENDED TAXI BACK TO W RAMP. CTLR FAILED TO MAINTAIN AWARENESS OF TFC IN PATTERN, CAUSING POTENTIAL MIDAIR COLLISION.

Data retrieved from NASA's ASRS site as of July 2007 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.