BACKUP RADAR SITES DO NOT PROVIDE ADEQUATE RADAR COVERAGE AT LOWER ALTS.

Narrative

THE KELLER RADAR SITE WAS TAKEN OTS DURING THIS TIME. RADAR TARGETS WERE BEING RECEIVED BY LONG RANGE RADAR AT OKC AND TXK. THIS SIT CAUSED NUMEROUS TARGET JUMPS OF AS MUCH AS PLUS OR MINUS 2 MI SIDE AND FRONT. AT ONE POINT; A PARALLEL TARGET APPEARED 6 MI TO THE SIDE OF ALL TARGETS. THE JUMPS ALSO CAUSED A SIGNIFICANT JUMP IN THE DISPLAYED GND SPD; AS MUCH AS PLUS OR MINUS 60 KTS. USING RADAR SEPARATION TO SEQUENCE ARRS IN THIS SECTOR IS VERY DANGEROUS. SPD AND TARGET JUMPS MAKE THE RADAR VERY UNRELIABLE. 1 PLT QUESTIONED LATERAL SEPARATION. AT THE TIME; THE ACFT WERE AT LEAST 7 MI IN TRAIL. DUE TO THE RADAR PROBS; THE TARGETS REGULARLY JUMPED TO AS CLOSE AS 4.5 MI (OVER 1000 FT VERT AT THE TIME SO 'NO LOSS OF SEPARATION') THEN BACK TO 7 MI. GND SPD DISPLAYED ALSO JUMPED; AVERAGING PLUS OR MINUS 30 KTS BUT AS MUCH AS PLUS OR MINUS 60 KTS. TO RESOLVE THIS PROB; I SUGGEST USING THE GREENVILLE (GVT) RADAR TO SUPPLEMENT CTR RADAR; OR BUILD ANOTHER SUPPLEMENTAL SITE. THE COST EFFECTIVE WOULD BE USING THE GVT RADAR SITE. THIS SITE IS ALREADY CERTIFIED FOR VFR ADVISORIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: CTLR STATES THAT PROB OCCURS WHENEVER THE KELLER RADAR SITE IS SHUT DOWN; NORMALLY FOR ROUTINE MAINT; AND THE OKC AND TXK RADAR SITES ARE USED AS A SUBSTITUTE. THIS IMPACTS 2 SECTORS N OF DFW; THE BLUE RIDGE AND SEAVR SECTORS. THE KELLER SITE IS LOCATED ABOUT 8 MI NW OF DTW. RPTR BELIEVES THAT THE SORT BOXES ARE THE MAIN CAUSE FOR JUMPING TARGETS. NO INCIDENTS OBSERVED OR RPTED TO THE RPTR'S KNOWLEDGE; BUT CTLRS ARE VERY AWARE OF THE PROBS WHEN THESE SITES ARE USED. IT APPEARS THAT THE SITES ARE TOO FAR AWAY TO PROVIDE ADEQUATE RADAR COVERAGE. AIRWAY FACILITIES VERY RESPONSIVE; BUT CAN ONLY DO SO MUCH. DEV IN AIRSPD STILL A PROB; BUT GETTING BETTER. RADAR SYS AT GREENVILLE IS A NON FAA RADAR SITE AND MAY NOT BE COMPATIBLE WITH ARTCC RADAR EQUIP. NORMALLY IMPACTS ACFT AT FL230 AND BELOW. ACFT DEPARTING DEP ARE NOT IDENTED UNTIL AT HIGHER ALTS.