Narrative:

On jul/sat/04, I was working potomac TRACON, chesapeake sector, wooly position. Air carrier X, a CRJ1, located 10 mi north of baltimore was instructed to cross baltimore at one zero thousand ft. I later observed a non-ARTS tag squawking XXXX at one zero thousand ft, 10 mi west of baltimore, heading eastbound. If the target was real, it would have been a direct conflict with air carrier X crossing baltimore at 10000 ft. I amended the altitude of air carrier X, and told him to stay at his present altitude of one two thousand ft. A fellow controller called me on the land line to ask if I also saw that target squawking XXXX at one zero thousand ft. I called an adjacent sector (ensue) to see if they had a 'runway.' they did not and did not observe the 'ghost' target. The 'ghost' target finally disappeared. After full routing the transponder code, it appears that target (XXXX) was about 40 mi northwest of baltimore. I feel there is a problem with the radar coverage at potomac TRACON. Management was alerted to this instance and others in the past. They deny there is a radar problem. How can controllers safely separate aircraft if 'ghost' targets appear? What if we turn an aircraft to avoid hitting a 'ghost' target only to put that aircraft in conflict with a 'real' target? This radar problem needs to be addressed in the interest of safety.

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Original NASA ASRS Text

Title: PCT CTLR EXPRESSED CONCERN REGARDING FALSE SECONDARY RADAR TARGET WHICH INDICATED TFC CONFLICTION.

Narrative: ON JUL/SAT/04, I WAS WORKING POTOMAC TRACON, CHESAPEAKE SECTOR, WOOLY POS. ACR X, A CRJ1, LOCATED 10 MI N OF BALTIMORE WAS INSTRUCTED TO CROSS BALTIMORE AT ONE ZERO THOUSAND FT. I LATER OBSERVED A NON-ARTS TAG SQUAWKING XXXX AT ONE ZERO THOUSAND FT, 10 MI W OF BALTIMORE, HDG EBOUND. IF THE TARGET WAS REAL, IT WOULD HAVE BEEN A DIRECT CONFLICT WITH ACR X XING BALTIMORE AT 10000 FT. I AMENDED THE ALT OF ACR X, AND TOLD HIM TO STAY AT HIS PRESENT ALT OF ONE TWO THOUSAND FT. A FELLOW CTLR CALLED ME ON THE LAND LINE TO ASK IF I ALSO SAW THAT TARGET SQUAWKING XXXX AT ONE ZERO THOUSAND FT. I CALLED AN ADJACENT SECTOR (ENSUE) TO SEE IF THEY HAD A 'RWY.' THEY DID NOT AND DID NOT OBSERVE THE 'GHOST' TARGET. THE 'GHOST' TARGET FINALLY DISAPPEARED. AFTER FULL ROUTING THE XPONDER CODE, IT APPEARS THAT TARGET (XXXX) WAS ABOUT 40 MI NW OF BALTIMORE. I FEEL THERE IS A PROB WITH THE RADAR COVERAGE AT POTOMAC TRACON. MGMNT WAS ALERTED TO THIS INSTANCE AND OTHERS IN THE PAST. THEY DENY THERE IS A RADAR PROB. HOW CAN CTLRS SAFELY SEPARATE ACFT IF 'GHOST' TARGETS APPEAR? WHAT IF WE TURN AN ACFT TO AVOID HITTING A 'GHOST' TARGET ONLY TO PUT THAT ACFT IN CONFLICT WITH A 'REAL' TARGET? THIS RADAR PROB NEEDS TO BE ADDRESSED IN THE INTEREST OF SAFETY.

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.