Narrative:

Approaching dsm at 5000 ft, we were told that radar was out and expect holding. Since we were approaching the VOR, I asked for a clearance. ATC seemed reluctant to give one, but cleared us to clive. After that, they cleared us to descend to 3000 ft but no other fix. It was hard to talk to the controllers as they also had a garbled transmitter. They wanted us to do a visual from over clive. The frequency was very congested. We finally told them we did not yet have the airport but were VMC over clive. They cleared us for the ILS runway 13L approach. We needed to reverse course for the approach so we tracked the localizer outbound, and reversed course in the depicted holding pattern then completed the approach. Upon debriefing the approach, we realized that we descended below 5000 ft using the GPS to identify clive. I probably should have revised their clearance and requested direct the VOR for the full approach from the IAF. But since we were VMC and the controller was so busy with the radar outage and poor communication equipment, I went right for the airport instead. Supplemental information from acn 442060: in vicinity of dsm VOR at 5000 ft MSL, we were cleared to clive intersection on the runway 13L ILS. We used GPS to identify clive. Approach control was very saturated with other aircraft, and the frequency seemed congested. En route to clive, we were given a descent to 3000 ft and advised the primary radar was down. We were also asked if we could accept a visual approach. We advised airport not in sight. We were cleared for the localizer runway 13L, which the captain had completely briefed earlier. We descended to 3000 ft, established ground contact, executed a course reversal and intercepted the runway 13L localizer inbound. We visually picked up the airport between huskr and clive, changed to tower and landed uneventfully. In retrospect, it may have been better to decline the approach controller, go direct to the dsm VOR and re-fly the entire approach. However, given the primary radar outage, number of aircraft in the vicinity of the airport and dsm VOR, a very busy approach controller made for a very difficult situation.

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Original NASA ASRS Text

Title: 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.

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.