Narrative:

Flight #XXX msp-bil was flown routinely to bil on 01/01/thur. WX had been reported and forecast as clear and 10 SM visibility. No alternate fuel was boarded, but 46 mins of contingency fuel was on board. At bil, the approach controller reported that visibility was deteriorating. We had briefed for a visual approach to runway 28 with the possibility of an ILS. We were at 11000 ft when approach said visibility was now 2 mi and we were given a descent clearance and then a left turn vector to intercept and clearance for straight-in ILS runway 28. The radios were tuned and idented for the ILS and the ADI GS indicators showed we were above the GS. Gear down and 40 degrees flaps were selected and a rapid descent on the localizer was commenced. Approaching 5000 ft, the first officer stated that he showed we were descending below the GS. My GS indicator on my ADI was still showing full deflection down, but my flight director v-bars were rising. I stopped the descent as we got an aural 'GS' warning and the tower called to say they had an altitude warning on us. I initiated a missed approach and we were vectored for an approach to runway 10L. I then remembered seeing a previous write-up in the logbook for this problem in which the pilot rapped on the ADI to unstick the GS indicator, and maintenance had cleared by testing and saying they could not duplicate. We shot the approach to runway 10L and landed as new WX reported at 1/2 mi visibility and 100 ft broken (local ground fog). Flight instruments all indicated normally. A radio repair station repairman came out to the airplane and tested the ADI and verified that it had stuck in the down position and the condition was intermittent. This incident was aggravated by encountering unforecast bad WX with a suddenly low fuel condition, no current WX reports for nearby airports, a last min approach clearance while high and seeing a local fog condition developing over the airport and feeling urgency to get on the ground before the WX went below minimums.

Google
 

Original NASA ASRS Text

Title: DC9 CREW, ON FINAL, LOST RELIABLE GS INDICATION IN #1 ADI.

Narrative: FLT #XXX MSP-BIL WAS FLOWN ROUTINELY TO BIL ON 01/01/THUR. WX HAD BEEN RPTED AND FORECAST AS CLR AND 10 SM VISIBILITY. NO ALTERNATE FUEL WAS BOARDED, BUT 46 MINS OF CONTINGENCY FUEL WAS ON BOARD. AT BIL, THE APCH CTLR RPTED THAT VISIBILITY WAS DETERIORATING. WE HAD BRIEFED FOR A VISUAL APCH TO RWY 28 WITH THE POSSIBILITY OF AN ILS. WE WERE AT 11000 FT WHEN APCH SAID VISIBILITY WAS NOW 2 MI AND WE WERE GIVEN A DSCNT CLRNC AND THEN A L TURN VECTOR TO INTERCEPT AND CLRNC FOR STRAIGHT-IN ILS RWY 28. THE RADIOS WERE TUNED AND IDENTED FOR THE ILS AND THE ADI GS INDICATORS SHOWED WE WERE ABOVE THE GS. GEAR DOWN AND 40 DEGS FLAPS WERE SELECTED AND A RAPID DSCNT ON THE LOC WAS COMMENCED. APCHING 5000 FT, THE FO STATED THAT HE SHOWED WE WERE DSNDING BELOW THE GS. MY GS INDICATOR ON MY ADI WAS STILL SHOWING FULL DEFLECTION DOWN, BUT MY FLT DIRECTOR V-BARS WERE RISING. I STOPPED THE DSCNT AS WE GOT AN AURAL 'GS' WARNING AND THE TWR CALLED TO SAY THEY HAD AN ALT WARNING ON US. I INITIATED A MISSED APCH AND WE WERE VECTORED FOR AN APCH TO RWY 10L. I THEN REMEMBERED SEEING A PREVIOUS WRITE-UP IN THE LOGBOOK FOR THIS PROB IN WHICH THE PLT RAPPED ON THE ADI TO UNSTICK THE GS INDICATOR, AND MAINT HAD CLRED BY TESTING AND SAYING THEY COULD NOT DUPLICATE. WE SHOT THE APCH TO RWY 10L AND LANDED AS NEW WX RPTED AT 1/2 MI VISIBILITY AND 100 FT BROKEN (LCL GND FOG). FLT INSTS ALL INDICATED NORMALLY. A RADIO REPAIR STATION REPAIRMAN CAME OUT TO THE AIRPLANE AND TESTED THE ADI AND VERIFIED THAT IT HAD STUCK IN THE DOWN POS AND THE CONDITION WAS INTERMITTENT. THIS INCIDENT WAS AGGRAVATED BY ENCOUNTERING UNFORECAST BAD WX WITH A SUDDENLY LOW FUEL CONDITION, NO CURRENT WX RPTS FOR NEARBY ARPTS, A LAST MIN APCH CLRNC WHILE HIGH AND SEEING A LCL FOG CONDITION DEVELOPING OVER THE ARPT AND FEELING URGENCY TO GET ON THE GND BEFORE THE WX WENT BELOW MINIMUMS.

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.