SMT IS FORCED TO EXECUTE MISSED APCH AFTER FINDING HIMSELF MORE THAN 4000 FT ABOVE THE ARPT WHILE FLYING AN ILS APCH.

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DSNDING TO ILS APCH RWY 22 RPTED WX 4600 SCATTERED; HIGHER (7000?) BROKEN; LIGHT RAIN EXPECTING HIGH RATE OF DSCNT (2500 FPM) TO BELOW CLOUDS AND PROCEED VISUALLY; WHILE MONITORING ILS ON AUTOPLT. HVY RAIN EXPERIENCED AFTER LOC INTERCEPT HIGH DSCNT RATE THROUGH GS CAUSED AUTOPLT TO PULL UP QUICKLY AFTER GOING 3 DOTS BELOW GS; AUTOPLT PULL-UP RESULTED IN TOO QUICK CLB AND I DISCONNECTED AUTOPLT TO FLY MANUALLY. AFTER 30-45 SECONDS OF MAINTAINING WITHIN 1 DOT LOC AND A CONSISTENT 1 DOT HIGH ON GS; GS STARTING FLUCTUATING WILDLY FULL SCALE BOTH DIRECTIONS. I THEN CALLED TWR TO ASK IF THERE HAD BEEN ANY GS PROBLEMS; AND HE SAID NO; AND THAT I WAS OVER THE ARPT AND TO SAY INTENTIONS (I WAS ABOUT 4000-4500 FT AGL IN IMC). I ASKED FOR VECTORS FOR ANOTHER APCH; AND MADE AN UNEVENTFUL HAND-FLOWN ILS. CEILING WAS ABOUT 1200 FT VISIBILITY 4600 SCATTERED THAT HAD BEEN RPTED. SINCE THE EVENT; I CONTACTED A FORMER INSTRUCTOR OF MINE AND RELATED THIS EPISODE TO HIM; SINCE I WAS CONFUSED AS TO WHAT HAD HAPPENED; AS I THOUGHT I WAS MAINTAINING A GOOD APCH PATH (THOUGH I DID KNOW I HAD PASSED THE OM; I DID NOT RECHK MY ALT -- ONLY AIRSPD; VERT SPD; AND HSI/GS). HE IMMEDIATELY ASSESSED THE SITUATION AS A 'FALSE GS'; SOMETHING THAT APPARENTLY OCCURS DURING AN ILS CAPTURE FROM A HIGH ALT. I WAS NOT AWARE OF THIS ANOMALY. TO PREVENT FURTHER OCCURRENCES I WILL: 1) NOT TRY EITHER A MANUAL OR AUTOPLT HIGH DSCNT RATE ILS CAPTURE. 2) EXPECT WORSE WX THAN RPTED (I WAS NOT MENTALLY PREPARED FOR THE FULL PROC). 3) XCHK ALT AT OM; AND DURING FINAL APCH. 4) RESPECT THE POSSIBILITY OF A 'FALSE GS'; AND NOT ATTEMPT CAPTURING GS FROM HIGH ALT.