Data block problem at air traffic facility on BRITE radar display.

Attributes
ACN	143216
Time
Date	199004
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mdw
State Reference	IL
Altitude	msl bound lower : 3500 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mdw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Experience	controller non radar : 8 flight time last 90 days : 15 flight time total : 180
ASRS Report	143216
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other
Situations
ATC Facility	other physical facility

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.

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.