Narrative:

I was conducting out at the ffo sh sector, and at approximately XA10Z air carrier X reported turbulence at FL370 and requested ride reports. Shortly thereafter, the ind radar clearance delivery (common digitizer) failed causing many of our radar targets to disappear, and new 'ghost' targets to appear tracking approximately 90 degrees left of the actual target. Not recognizing air carrier Y as traffic, the trainee descended air carrier X to FL330. Air carrier X's real target had disappeared and it appeared as if an imminent situation was developing between air carrier X and air carrier Z. However, air carrier X was tracking on a ghost target and was nowhere near air carrier Z. Air carrier X was 'nose to nose' with air carrier Y. When I realized that something was wrong, I immediately told air carrier X to stay at FL370. It took several mins for all targets to correlate on their original, 'true' targets. At one instant, a mode C intruder appeared at FL370. It turned out to be another air carrier, who was still abeam indianapolis 80 mi west. This was a very scary situation especially since conflict alert activated between air carrier Z and air carrier X who were really not traffic. The natural reaction would have been to descend air carrier X, but that would have been disastrous with air carrier Y.

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Original NASA ASRS Text

Title: RADAR COMMON DIGITIZER FAILS CAUSING GHOST TARGETS TO OFFSET ACTUAL TARGETS. CTLR ISSUED DSCNT BASED UPON FALSE TARGETS TOWARDS OPPOSITE DIRECTION TFC BELOW. CTLR INSTRUCTOR STOPPED THE DSCNT BEFORE LOSS OF SEPARATION.

Narrative: I WAS CONDUCTING OUT AT THE FFO SH SECTOR, AND AT APPROX XA10Z ACR X RPTED TURB AT FL370 AND REQUESTED RIDE RPTS. SHORTLY THEREAFTER, THE IND RADAR CD (COMMON DIGITIZER) FAILED CAUSING MANY OF OUR RADAR TARGETS TO DISAPPEAR, AND NEW 'GHOST' TARGETS TO APPEAR TRACKING APPROX 90 DEGS L OF THE ACTUAL TARGET. NOT RECOGNIZING ACR Y AS TFC, THE TRAINEE DSNDED ACR X TO FL330. ACR X'S REAL TARGET HAD DISAPPEARED AND IT APPEARED AS IF AN IMMINENT SIT WAS DEVELOPING BTWN ACR X AND ACR Z. HOWEVER, ACR X WAS TRACKING ON A GHOST TARGET AND WAS NOWHERE NEAR ACR Z. ACR X WAS 'NOSE TO NOSE' WITH ACR Y. WHEN I REALIZED THAT SOMETHING WAS WRONG, I IMMEDIATELY TOLD ACR X TO STAY AT FL370. IT TOOK SEVERAL MINS FOR ALL TARGETS TO CORRELATE ON THEIR ORIGINAL, 'TRUE' TARGETS. AT ONE INSTANT, A MODE C INTRUDER APPEARED AT FL370. IT TURNED OUT TO BE ANOTHER ACR, WHO WAS STILL ABEAM INDIANAPOLIS 80 MI W. THIS WAS A VERY SCARY SIT ESPECIALLY SINCE CONFLICT ALERT ACTIVATED BTWN ACR Z AND ACR X WHO WERE REALLY NOT TFC. THE NATURAL REACTION WOULD HAVE BEEN TO DSND ACR X, BUT THAT WOULD HAVE BEEN DISASTROUS WITH ACR Y.

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.