Narrative:

At various and random times the data block will disassociate itself from the primary (altitude remains) target and advance across the radar (BRITE) scope at what seems to be 1000 mph for about 10 mi. It will then reacquire to its original and correct target and continue as normal. This situation has caused apprehension on my part at least once when I, because the first arrival was more than 5 mi away, cleared an air carrier for takeoff. When the aircraft was lining up for departure I looked at the BRITE only to see what appeared to be another air carrier on about a 1/2 mi final. At the time it was VFR and a look out the window eliminated my fears; however, had it been IMC, the situation could have been quite different. Callback conversation with reporter revealed the following: reporter says that this is an intermittent problem that has been ongoing for approximately 2 months. He said that it occurs about 2-3 times/day in various areas. It is not confined to only the final approach. He doesn't know if ord is also having the problem. No ucr has been filed, but each time it has occurred, the supervisor was alerted. Reporter said the aircraft involved was an medium large transport landing on runway 31L. No loss of sep or incident has been caused by this problem so far.

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Original NASA ASRS Text

Title: DATA BLOCK PROBLEM AT AIR TRAFFIC FAC ON BRITE RADAR DISPLAY.

Narrative: AT VARIOUS AND RANDOM TIMES THE DATA BLOCK WILL DISASSOCIATE ITSELF FROM THE PRIMARY (ALT REMAINS) TARGET AND ADVANCE ACROSS THE RADAR (BRITE) SCOPE AT WHAT SEEMS TO BE 1000 MPH FOR ABOUT 10 MI. IT WILL THEN REACQUIRE TO ITS ORIGINAL AND CORRECT TARGET AND CONTINUE AS NORMAL. THIS SITUATION HAS CAUSED APPREHENSION ON MY PART AT LEAST ONCE WHEN I, BECAUSE THE FIRST ARR WAS MORE THAN 5 MI AWAY, CLRED AN ACR FOR TKOF. WHEN THE ACFT WAS LINING UP FOR DEP I LOOKED AT THE BRITE ONLY TO SEE WHAT APPEARED TO BE ANOTHER ACR ON ABOUT A 1/2 MI FINAL. AT THE TIME IT WAS VFR AND A LOOK OUT THE WINDOW ELIMINATED MY FEARS; HOWEVER, HAD IT BEEN IMC, THE SITUATION COULD HAVE BEEN QUITE DIFFERENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR SAYS THAT THIS IS AN INTERMITTENT PROB THAT HAS BEEN ONGOING FOR APPROX 2 MONTHS. HE SAID THAT IT OCCURS ABOUT 2-3 TIMES/DAY IN VARIOUS AREAS. IT IS NOT CONFINED TO ONLY THE FINAL APCH. HE DOESN'T KNOW IF ORD IS ALSO HAVING THE PROB. NO UCR HAS BEEN FILED, BUT EACH TIME IT HAS OCCURRED, THE SUPVR WAS ALERTED. RPTR SAID THE ACFT INVOLVED WAS AN MLG LNDG ON RWY 31L. NO LOSS OF SEP OR INCIDENT HAS BEEN CAUSED BY THIS PROB SO FAR.

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.