ATC RADAR EQUIP PROB RADAR ARTS MODE C UNRELIABLE.

Narrative

THE MODE C AT LFT HAS BEEN SHOWING 'XXX' VERY FREQUENTLY INSTEAD OF AN ALT READOUT. THIS SIT HAS BEEN OCCURRING FOR ABOUT 6 MONTHS. WITHIN THE LAST 2 WKS THE MODE C HAD BEEN ERRONEOUS AS WELL AS THE 'XXX'S.' THE ERRONEOUS ALT RPTS OR NO READOUT AT ALL HAS CAUSED SEVERAL SITS THAT COULD HAVE RESULTED IN A NEAR MISS OR A COLLISION. NO ONE SEEMS TO KNOW WHY THE READOUTS ARE A PROB. IT HAS YET TO BE DETERMINED WHETHER THE PROB LIES IN THE HARDWARE OR SOFTWARE. THE SW REGIONAL OFFICE HAS BECOME AWARE OF THE PROB AND ORDERED THE FACILITY TO INHIBIT THE MODE C READOUT. THIS SIT IS ALSO UNACCEPTABLE. THE WORKLOAD HAS INCREASED THREEFOLD. MORE TIME IS SPENT COORDINATING THAN VIEWING THE TFC. THIS SIT NEEDS TO BE CORRECTED ASAP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: PLANNING AND PROCS SPECIALIST WAS CONTACTED ABOUT MODE C PROB. HE STATED THE MODE C WAS TAKEN OTS BEFORE A FACILITY EVALUATION. ARTS MODE C WAS RETURNED TO SVC IN 30 DAYS. REASON FOR MODE C UNRELIABILITY WAS NOT DETERMINED. FAA MAINT CHANGED SOME COMPONENTS AND THE MODE C WORKED CORRECTLY.