Narrative:

I had an air carrier X on radar vectors for a visual approach runway 11 at ewr at 3000 MSL. Another controller working a combined position took radar on another aircraft Y from another facility. This was not SOP. Bad radar coverage caused aircraft Y ARTS IIIA tag to drop. Since other controller was busy due to combined position, the controller did not notice such. Aircraft Y tag re-acquired co-located with air carrier X on my frequency. Air carrier X took a sharp turn to avoid a midair. The supervisor called in sick which left the sector with 1 data aide, 7 fpl, 1 controller in charge. This is very understaffed and more controllers would have prevented this situation.

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Original NASA ASRS Text

Title: TRACON INTERFAC COORD ACFT Y UNCOORD UNAUTH PENETRATION OF AIRSPACE HAD LTSS WITH ACR X EVASIVE ACTION TAKEN. SYS ERROR.

Narrative: I HAD AN ACR X ON RADAR VECTORS FOR A VISUAL APCH RWY 11 AT EWR AT 3000 MSL. ANOTHER CTLR WORKING A COMBINED POS TOOK RADAR ON ANOTHER ACFT Y FROM ANOTHER FACILITY. THIS WAS NOT SOP. BAD RADAR COVERAGE CAUSED ACFT Y ARTS IIIA TAG TO DROP. SINCE OTHER CTLR WAS BUSY DUE TO COMBINED POS, THE CTLR DID NOT NOTICE SUCH. ACFT Y TAG RE-ACQUIRED CO-LOCATED WITH ACR X ON MY FREQ. ACR X TOOK A SHARP TURN TO AVOID A MIDAIR. THE SUPVR CALLED IN SICK WHICH LEFT THE SECTOR WITH 1 DATA AIDE, 7 FPL, 1 CIC. THIS IS VERY UNDERSTAFFED AND MORE CTLRS WOULD HAVE PREVENTED THIS SIT.

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.