Narrative:

Dulles was in a limited radar capacity using cenrap radar. On 2 occasions during my time on this position, my a/north's and virgiles 'flickered.' I, and other controllers in my facility were having problems tracking radar targets. I was routinely losing virgiles, and on many occasions lost both virgiles and a/north's. A few aircraft (maybe 3 or 4) that were supposed to be in the limits of my radar coverage, went into 'CST' status for 2 or more sweeps. Air carrier X came into my airspace over robrt at 10000 ft. I instructed air carrier X to 'expect visual approach runway 1R, cross 20 mi northwest of armel at 5000 ft.' approximately 5 mi south of the fdk VOR, air carrier X informed me 'air carrier X is filing a near midair now.' I then told air carrier X that I observed a VFR target small aircraft Y 6 O'clock less than 1 mi, nebound, estimated, indicating 5700 ft unverified. I did not issue the traffic prior to air carrier X report, nor was traffic observed prior to air carrier X report. I informed the supervisor, as did I inform him of the radar problems I was experiencing prior to the incident. Callback conversation with reporter revealed the following: reporter stated that air carrier X took evasive action because of TCASII RA. Reporter failed to issue traffic because with the radar problems she was taking a manual radar handoff from another position and was distracted.

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Original NASA ASRS Text

Title: ATC EQUIP PROB RADAR ACR X TCASII RA WITH VFR SMA Y. EVASIVE ACTION TAKEN.

Narrative: DULLES WAS IN A LIMITED RADAR CAPACITY USING CENRAP RADAR. ON 2 OCCASIONS DURING MY TIME ON THIS POS, MY A/N'S AND VIRGILES 'FLICKERED.' I, AND OTHER CTLRS IN MY FACILITY WERE HAVING PROBS TRACKING RADAR TARGETS. I WAS ROUTINELY LOSING VIRGILES, AND ON MANY OCCASIONS LOST BOTH VIRGILES AND A/N'S. A FEW ACFT (MAYBE 3 OR 4) THAT WERE SUPPOSED TO BE IN THE LIMITS OF MY RADAR COVERAGE, WENT INTO 'CST' STATUS FOR 2 OR MORE SWEEPS. ACR X CAME INTO MY AIRSPACE OVER ROBRT AT 10000 FT. I INSTRUCTED ACR X TO 'EXPECT VISUAL APCH RWY 1R, CROSS 20 MI NW OF ARMEL AT 5000 FT.' APPROX 5 MI S OF THE FDK VOR, ACR X INFORMED ME 'ACR X IS FILING A NEAR MIDAIR NOW.' I THEN TOLD ACR X THAT I OBSERVED A VFR TARGET SMA Y 6 O'CLOCK LESS THAN 1 MI, NEBOUND, ESTIMATED, INDICATING 5700 FT UNVERIFIED. I DID NOT ISSUE THE TFC PRIOR TO ACR X RPT, NOR WAS TFC OBSERVED PRIOR TO ACR X RPT. I INFORMED THE SUPVR, AS DID I INFORM HIM OF THE RADAR PROBS I WAS EXPERIENCING PRIOR TO THE INCIDENT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR STATED THAT ACR X TOOK EVASIVE ACTION BECAUSE OF TCASII RA. RPTR FAILED TO ISSUE TFC BECAUSE WITH THE RADAR PROBS SHE WAS TAKING A MANUAL RADAR HDOF FROM ANOTHER POS AND WAS DISTRACTED.

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.