Narrative:

I was returning from boone, ia, to fort collins-loveland, co, (fnl) on an IFR flight plan. I had been flying in IMC for about 2 hours and was a few mi east of the gill VOR at 8000' MSL. I requested and received clearance for the VOR DME-a approach into fnl to remain at 7000' until established on the approach. Descending from 8000' to 7000' east of gill VOR, I broke out of the clouds but since it was raining hard, reducing forward visibility I decided to continue the approach. I have flown this approach, both practice and actual many times since fnl is my home airport, so I know the approach. For unknown reasons, I began descent to the intermediate altitude of 6300' at the VOR instead of neffs as shown on the approach plate. I then began a descent to the MDA at neffs instead of ebbie as shown on the approach plate. I realized my error as I passed the tower shown on the approach plate and it was closer in altitude than it should have been. The airport was now in sight so I cancelled IFR and circled to make a normal landing on runway 33 fnl. I did hit some turbulence on the approach, but not enough that it should have been distracting. Nearby thunderstorms also caused some radio static. I had sufficient sleep and the flight had been uneventful except for a temporary autoplt failure to engage early in the flight. Even though I know the correct approach procedure, that day I had it set in my mind to descend at the wrong intxns. I will never take a familiar approach for granted again.

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Original NASA ASRS Text

Title: SMA PLT ON VOR DME APCH DESCENDS TOO SOON, FLIES BELOW PUBLISHED ALT.

Narrative: I WAS RETURNING FROM BOONE, IA, TO FORT COLLINS-LOVELAND, CO, (FNL) ON AN IFR FLT PLAN. I HAD BEEN FLYING IN IMC FOR ABOUT 2 HRS AND WAS A FEW MI E OF THE GILL VOR AT 8000' MSL. I REQUESTED AND RECEIVED CLRNC FOR THE VOR DME-A APCH INTO FNL TO REMAIN AT 7000' UNTIL ESTABLISHED ON THE APCH. DSNDING FROM 8000' TO 7000' E OF GILL VOR, I BROKE OUT OF THE CLOUDS BUT SINCE IT WAS RAINING HARD, REDUCING FORWARD VISIBILITY I DECIDED TO CONTINUE THE APCH. I HAVE FLOWN THIS APCH, BOTH PRACTICE AND ACTUAL MANY TIMES SINCE FNL IS MY HOME ARPT, SO I KNOW THE APCH. FOR UNKNOWN REASONS, I BEGAN DSNT TO THE INTERMEDIATE ALT OF 6300' AT THE VOR INSTEAD OF NEFFS AS SHOWN ON THE APCH PLATE. I THEN BEGAN A DSNT TO THE MDA AT NEFFS INSTEAD OF EBBIE AS SHOWN ON THE APCH PLATE. I REALIZED MY ERROR AS I PASSED THE TWR SHOWN ON THE APCH PLATE AND IT WAS CLOSER IN ALT THAN IT SHOULD HAVE BEEN. THE ARPT WAS NOW IN SIGHT SO I CANCELLED IFR AND CIRCLED TO MAKE A NORMAL LNDG ON RWY 33 FNL. I DID HIT SOME TURB ON THE APCH, BUT NOT ENOUGH THAT IT SHOULD HAVE BEEN DISTRACTING. NEARBY TSTMS ALSO CAUSED SOME RADIO STATIC. I HAD SUFFICIENT SLEEP AND THE FLT HAD BEEN UNEVENTFUL EXCEPT FOR A TEMPORARY AUTOPLT FAILURE TO ENGAGE EARLY IN THE FLT. EVEN THOUGH I KNOW THE CORRECT APCH PROC, THAT DAY I HAD IT SET IN MY MIND TO DSND AT THE WRONG INTXNS. I WILL NEVER TAKE A FAMILIAR APCH FOR GRANTED AGAIN.

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.