Narrative:

On an IFR flight plan for gmu, sc. To meigs field (cgx) chicago. About 100 mi out, listening to cgx ATIS, ATIS was reporting ceiling of 400 ft, below IFR minimums. Continued monitoring gave the same information. Chicago approach indicated meigs was closed and I told them I would take my alternate of mdw airport. I had been descended to 4000 ft MSL and given a vector for the runway 31C approach to mdw. The controller wanted to know how fast I could fly at present. I told him my indicated airspeed was 145 KIAS. He said that was fine and 'keep the speed up.' I noticed on my moving map GPS that he was running me through the localizer. Shortly afterwards, he turned me back to intercept the localizer. He advised me to 'caution for wake turbulence' as I was following a big heavy, and to continue to keep my speed up. He mentioned that if he had forgot to clear me for the approach (which he had forgot to do) that I was cleared and contact mdw tower. When I contacted tower, they informed me that meigs was at 800 ft and did I want a special when I broke out to go to meigs. I told them I would continue on to mdw -- both moving map GPS's and the HSI were centered on the localizer. As the GS started to come alive I put in 1 notch of flaps (approach flaps). The autoplt was holding centerline in approach mode. When the GS centered, I reached over and lowered the gear. I felt the drag as the gear extended. I checked to see that I had 3 green lights -- I did. I checked back to the instruments and found that I was in a 60 degree bank to the left and in a rapid descent. The controller asked what I was doing. I was trying to roll out the bank and stop the descent as I talked to him to tell him we had an autoplt failure. I told him we had an emergency situation. How much he heard, I'm not sure, as I was trying to regain control of the airplane and was not aware of how much I was pushing the push-to-talk button. He told me to turn right to 090 degrees and level at 2500 ft. As we approached the new heading, he changed the altitude to 2000 ft and told me to turn left to 300 degrees and track it in, next to descend to 1500 ft. Before reaching 1500 ft, we broke out of the clouds. He asked if we needed assistance. I said no, that we had an autoplt failure. He said 'have a nice day' as we landed.

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Original NASA ASRS Text

Title: BE36 PLT DIVERTS TO MDW FROM CG FOR WX REASONS THEN LOSES CTL OF ACFT WHEN AUTOPLT FAILS DURING RWY 31C ILS APCH TO MDW, IL.

Narrative: ON AN IFR FLT PLAN FOR GMU, SC. TO MEIGS FIELD (CGX) CHICAGO. ABOUT 100 MI OUT, LISTENING TO CGX ATIS, ATIS WAS RPTING CEILING OF 400 FT, BELOW IFR MINIMUMS. CONTINUED MONITORING GAVE THE SAME INFO. CHICAGO APCH INDICATED MEIGS WAS CLOSED AND I TOLD THEM I WOULD TAKE MY ALTERNATE OF MDW ARPT. I HAD BEEN DSNDED TO 4000 FT MSL AND GIVEN A VECTOR FOR THE RWY 31C APCH TO MDW. THE CTLR WANTED TO KNOW HOW FAST I COULD FLY AT PRESENT. I TOLD HIM MY INDICATED AIRSPD WAS 145 KIAS. HE SAID THAT WAS FINE AND 'KEEP THE SPD UP.' I NOTICED ON MY MOVING MAP GPS THAT HE WAS RUNNING ME THROUGH THE LOC. SHORTLY AFTERWARDS, HE TURNED ME BACK TO INTERCEPT THE LOC. HE ADVISED ME TO 'CAUTION FOR WAKE TURB' AS I WAS FOLLOWING A BIG HVY, AND TO CONTINUE TO KEEP MY SPD UP. HE MENTIONED THAT IF HE HAD FORGOT TO CLR ME FOR THE APCH (WHICH HE HAD FORGOT TO DO) THAT I WAS CLRED AND CONTACT MDW TWR. WHEN I CONTACTED TWR, THEY INFORMED ME THAT MEIGS WAS AT 800 FT AND DID I WANT A SPECIAL WHEN I BROKE OUT TO GO TO MEIGS. I TOLD THEM I WOULD CONTINUE ON TO MDW -- BOTH MOVING MAP GPS'S AND THE HSI WERE CTRED ON THE LOC. AS THE GS STARTED TO COME ALIVE I PUT IN 1 NOTCH OF FLAPS (APCH FLAPS). THE AUTOPLT WAS HOLDING CTRLINE IN APCH MODE. WHEN THE GS CTRED, I REACHED OVER AND LOWERED THE GEAR. I FELT THE DRAG AS THE GEAR EXTENDED. I CHKED TO SEE THAT I HAD 3 GREEN LIGHTS -- I DID. I CHKED BACK TO THE INSTS AND FOUND THAT I WAS IN A 60 DEG BANK TO THE L AND IN A RAPID DSCNT. THE CTLR ASKED WHAT I WAS DOING. I WAS TRYING TO ROLL OUT THE BANK AND STOP THE DSCNT AS I TALKED TO HIM TO TELL HIM WE HAD AN AUTOPLT FAILURE. I TOLD HIM WE HAD AN EMER SIT. HOW MUCH HE HEARD, I'M NOT SURE, AS I WAS TRYING TO REGAIN CTL OF THE AIRPLANE AND WAS NOT AWARE OF HOW MUCH I WAS PUSHING THE PUSH-TO-TALK BUTTON. HE TOLD ME TO TURN R TO 090 DEGS AND LEVEL AT 2500 FT. AS WE APCHED THE NEW HDG, HE CHANGED THE ALT TO 2000 FT AND TOLD ME TO TURN L TO 300 DEGS AND TRACK IT IN, NEXT TO DSND TO 1500 FT. BEFORE REACHING 1500 FT, WE BROKE OUT OF THE CLOUDS. HE ASKED IF WE NEEDED ASSISTANCE. I SAID NO, THAT WE HAD AN AUTOPLT FAILURE. HE SAID 'HAVE A NICE DAY' AS WE LANDED.

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.