Narrative:

Tcu/cumulo nimbus clouds were on most of the route. I was routed around some of it; then RNAV direct to slk. At 15 mi out; there was another buildup; heavy enough I didn't deem it safe to go through to get to the slk VOR; so I asked for direct briel. I was given that and to maintain 6800 ft until briel outbound and cleared for the ILS 23 approach. I did not reprogram the RNAV; I was using the NDB only for navigation. I was in IMC at this point; with moderate turbulence. From previous conversations with the center controller and from onboard radar; I knew there were more buildups north and south of my current position by about 25 mi in either direction. As a result; as soon as I saw the ADF needle turning rapidly; what I believed to be station passage; and started the descent. At 6000 ft I got a call from the center controller saying that I was not outbound from briel and that I was 800 ft low. I stopped the descent; and as I had broken out and was in the valley; could clearly see the field; I canceled the IFR; descended normally and made an uneventful landing. Things I should have done differently: 1) used the VOR/DME as a backup for the information received from the ADF. I believe the ADF was inaccurate due to the mountains. 2) more seriously considered a hold or diversion until the buildups had passed so I didn't have to be so concerned with a descent between 2 buildups. I decided neither of these options were good ones considering the speed at which the buildups were occurring; lateness of the flight (45 mins behind schedule); and flight time (already at 6.6 hours at the time of the decision). I suspected I didn't have the flight time available to divert to plattsburg; wait out the buildups; and still get into saranac lake. Other contributing factors: fatigue -- this shift is a normally-scheduled 13.5 hour duty day that regular goes to 14; and in that shift I fly between 6-8 flight hours single pilot. I believe this is too long a day with too much flying time under difficult conditions.

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Original NASA ASRS Text

Title: SINGLE PLT SMT DESCENDS PRIOR TO CROSSING BRIEL OUTBOUND FOR ILS 23 IAP TO SLK.

Narrative: TCU/CUMULO NIMBUS CLOUDS WERE ON MOST OF THE RTE. I WAS ROUTED AROUND SOME OF IT; THEN RNAV DIRECT TO SLK. AT 15 MI OUT; THERE WAS ANOTHER BUILDUP; HVY ENOUGH I DIDN'T DEEM IT SAFE TO GO THROUGH TO GET TO THE SLK VOR; SO I ASKED FOR DIRECT BRIEL. I WAS GIVEN THAT AND TO MAINTAIN 6800 FT UNTIL BRIEL OUTBOUND AND CLRED FOR THE ILS 23 APCH. I DID NOT REPROGRAM THE RNAV; I WAS USING THE NDB ONLY FOR NAV. I WAS IN IMC AT THIS POINT; WITH MODERATE TURB. FROM PREVIOUS CONVERSATIONS WITH THE CTR CTLR AND FROM ONBOARD RADAR; I KNEW THERE WERE MORE BUILDUPS N AND S OF MY CURRENT POS BY ABOUT 25 MI IN EITHER DIRECTION. AS A RESULT; AS SOON AS I SAW THE ADF NEEDLE TURNING RAPIDLY; WHAT I BELIEVED TO BE STATION PASSAGE; AND STARTED THE DSCNT. AT 6000 FT I GOT A CALL FROM THE CTR CTLR SAYING THAT I WAS NOT OUTBOUND FROM BRIEL AND THAT I WAS 800 FT LOW. I STOPPED THE DSCNT; AND AS I HAD BROKEN OUT AND WAS IN THE VALLEY; COULD CLRLY SEE THE FIELD; I CANCELED THE IFR; DSNDED NORMALLY AND MADE AN UNEVENTFUL LNDG. THINGS I SHOULD HAVE DONE DIFFERENTLY: 1) USED THE VOR/DME AS A BACKUP FOR THE INFO RECEIVED FROM THE ADF. I BELIEVE THE ADF WAS INACCURATE DUE TO THE MOUNTAINS. 2) MORE SERIOUSLY CONSIDERED A HOLD OR DIVERSION UNTIL THE BUILDUPS HAD PASSED SO I DIDN'T HAVE TO BE SO CONCERNED WITH A DSCNT BTWN 2 BUILDUPS. I DECIDED NEITHER OF THESE OPTIONS WERE GOOD ONES CONSIDERING THE SPD AT WHICH THE BUILDUPS WERE OCCURRING; LATENESS OF THE FLT (45 MINS BEHIND SCHEDULE); AND FLT TIME (ALREADY AT 6.6 HRS AT THE TIME OF THE DECISION). I SUSPECTED I DIDN'T HAVE THE FLT TIME AVAILABLE TO DIVERT TO PLATTSBURG; WAIT OUT THE BUILDUPS; AND STILL GET INTO SARANAC LAKE. OTHER CONTRIBUTING FACTORS: FATIGUE -- THIS SHIFT IS A NORMALLY-SCHEDULED 13.5 HR DUTY DAY THAT REGULAR GOES TO 14; AND IN THAT SHIFT I FLY BTWN 6-8 FLT HRS SINGLE PLT. I BELIEVE THIS IS TOO LONG A DAY WITH TOO MUCH FLYING TIME UNDER DIFFICULT CONDITIONS.

Data retrieved from NASA's ASRS site as of May 2009 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.