MD80 CREW HAD APCH RADAR OUTAGE AT DSM.

Narrative

APCHING DSM AT 5000 FT; WE WERE TOLD THAT RADAR WAS OUT AND EXPECT HOLDING. SINCE WE WERE APCHING THE VOR; I ASKED FOR A CLRNC. ATC SEEMED RELUCTANT TO GIVE ONE; BUT CLRED US TO CLIVE. AFTER THAT; THEY CLRED US TO DSND TO 3000 FT BUT NO OTHER FIX. IT WAS HARD TO TALK TO THE CTLRS AS THEY ALSO HAD A GARBLED XMITTER. THEY WANTED US TO DO A VISUAL FROM OVER CLIVE. THE FREQ WAS VERY CONGESTED. WE FINALLY TOLD THEM WE DID NOT YET HAVE THE ARPT BUT WERE VMC OVER CLIVE. THEY CLRED US FOR THE ILS RWY 13L APCH. WE NEEDED TO REVERSE COURSE FOR THE APCH SO WE TRACKED THE LOC OUTBOUND; AND REVERSED COURSE IN THE DEPICTED HOLDING PATTERN THEN COMPLETED THE APCH. UPON DEBRIEFING THE APCH; WE REALIZED THAT WE DSNDED BELOW 5000 FT USING THE GPS TO IDENT CLIVE. I PROBABLY SHOULD HAVE REVISED THEIR CLRNC AND REQUESTED DIRECT THE VOR FOR THE FULL APCH FROM THE IAF. BUT SINCE WE WERE VMC AND THE CTLR WAS SO BUSY WITH THE RADAR OUTAGE AND POOR COM EQUIP; I WENT RIGHT FOR THE ARPT INSTEAD. SUPPLEMENTAL INFO FROM ACN 442060: IN VICINITY OF DSM VOR AT 5000 FT MSL; WE WERE CLRED TO CLIVE INTXN ON THE RWY 13L ILS. WE USED GPS TO IDENT CLIVE. APCH CTL WAS VERY SATURATED WITH OTHER ACFT; AND THE FREQ SEEMED CONGESTED. ENRTE TO CLIVE; WE WERE GIVEN A DSCNT TO 3000 FT AND ADVISED THE PRIMARY RADAR WAS DOWN. WE WERE ALSO ASKED IF WE COULD ACCEPT A VISUAL APCH. WE ADVISED ARPT NOT IN SIGHT. WE WERE CLRED FOR THE LOC RWY 13L; WHICH THE CAPT HAD COMPLETELY BRIEFED EARLIER. WE DSNDED TO 3000 FT; ESTABLISHED GND CONTACT; EXECUTED A COURSE REVERSAL AND INTERCEPTED THE RWY 13L LOC INBOUND. WE VISUALLY PICKED UP THE ARPT BTWN HUSKR AND CLIVE; CHANGED TO TWR AND LANDED UNEVENTFULLY. IN RETROSPECT; IT MAY HAVE BEEN BETTER TO DECLINE THE APCH CTLR; GO DIRECT TO THE DSM VOR AND RE-FLY THE ENTIRE APCH. HOWEVER; GIVEN THE PRIMARY RADAR OUTAGE; NUMBER OF ACFT IN THE VICINITY OF THE ARPT AND DSM VOR; A VERY BUSY APCH CTLR MADE FOR A VERY DIFFICULT SIT.