Narrative:

I was approaching smx using LORAN guidance. The HSI was switched to the LORAN so the autoplt could track it en route. I contacted vandenberg approach about 10 northwest of mqo for the ILS to smx (WX was reported 500' broken, visibility 6 mi). LORAN course was 128 degrees, maintain VFR at 3500'. After mqo, approach vectored me 090 degrees for spacing, for about 5 mi. Next vector was 240 degrees (ATC did advise base leg). This was a right turn of 150 degrees, rather a radical vector. Tops of the overcast were 1200' MSL; I was advised to descend to 3000'. I tuned and idented the ILS, and set the HSI course printer to the 120 degree inbound ILS course. WX was now reported 400' overcast, visibility 3 min in fog. The turn to the localizer (inbound course 120 degrees) was a 120 degree left turn about 3 mi from the OM, hardly a normal intercept. Cleared for the approach, approach advised radar contact lost, 'contact the tower.' I had not switched the HSI from LORAN to the VOR receiver, and was therefore using the LORAN output as if it were the ILS. Its blue reminder annunciator, which had been on for the entire flight, should have now meant warning, but there is no change to indicate it's more important status during the approach phase. I understand certain systems are wired with an ILS override relay, but mine is not (factory installed systems by xx aircraft corp). I am not sure whether the manufacturer provides such an ILS signal to external devices. My assumption was that the G/south pointers were buried in the bottom of the display because we were in a slamdunk, above the G/south approach. I descended aggressively to reach the G/south. Descent continued until I began to level off at 500' MSL, reaching about 400' MSL (DH is 437' MSL). Still IMC, I noted we were several mi from the field and the G/south had never appeared. I had fixated on getting a G/south and wasn't x-chking altitude. I instituted an immediate climb, declaring a missed approach. Our estimated position at the miss was just inside the OM (though we never heard it). The 128 degree LORAN course would have put us about 1 mi east of the localizer. This position is within a mi of a radio tower at 425' MSL. On the return vector, I realized the error and the second approach completed normally. The unusual vectoring by vandenberg approach, even though we were VMC, was a distraction. If normal procedure for a military facility is to vector for a close-in base leg intercept, then civil pilots should be aware of this and be ready. On the second approach, tower asked us to report the OM; we'd already passed it before the handoff from approach was completed. Corrective actions: 1) IFR proficiency training. Though I've got plenty of IFR experience, a few hours with picky cfii or safety pilot will sharpen my detail skills during the approach phase. Much of our IFR time is spent in cruise and flying relatively simple approachs. Fixation on reaching the G/south was probably due to my mindset caused by the slam dunk approach. This set up an expectation that the G/south would be reached, causing me to ignore the altitude xchk during the descent.

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Original NASA ASRS Text

Title: PLT ON VECTORS FROM MIL FAC CLEARED FOR APCH. MISSET LORAN EQUIPMENT AND DESCENDED BELOW PUBLISHED ALT PRIOR TO GS INTERCEPT. EXECUTED MISSED APCH.

Narrative: I WAS APCHING SMX USING LORAN GUIDANCE. THE HSI WAS SWITCHED TO THE LORAN SO THE AUTOPLT COULD TRACK IT ENRTE. I CONTACTED VANDENBERG APCH ABOUT 10 NW OF MQO FOR THE ILS TO SMX (WX WAS RPTED 500' BROKEN, VISIBILITY 6 MI). LORAN COURSE WAS 128 DEGS, MAINTAIN VFR AT 3500'. AFTER MQO, APCH VECTORED ME 090 DEGS FOR SPACING, FOR ABOUT 5 MI. NEXT VECTOR WAS 240 DEGS (ATC DID ADVISE BASE LEG). THIS WAS A RIGHT TURN OF 150 DEGS, RATHER A RADICAL VECTOR. TOPS OF THE OVCST WERE 1200' MSL; I WAS ADVISED TO DSND TO 3000'. I TUNED AND IDENTED THE ILS, AND SET THE HSI COURSE PRINTER TO THE 120 DEG INBND ILS COURSE. WX WAS NOW RPTED 400' OVCST, VISIBILITY 3 MIN IN FOG. THE TURN TO THE LOC (INBND COURSE 120 DEGS) WAS A 120 DEG LEFT TURN ABOUT 3 MI FROM THE OM, HARDLY A NORMAL INTERCEPT. CLRED FOR THE APCH, APCH ADVISED RADAR CONTACT LOST, 'CONTACT THE TWR.' I HAD NOT SWITCHED THE HSI FROM LORAN TO THE VOR RECEIVER, AND WAS THEREFORE USING THE LORAN OUTPUT AS IF IT WERE THE ILS. ITS BLUE REMINDER ANNUNCIATOR, WHICH HAD BEEN ON FOR THE ENTIRE FLT, SHOULD HAVE NOW MEANT WARNING, BUT THERE IS NO CHANGE TO INDICATE IT'S MORE IMPORTANT STATUS DURING THE APCH PHASE. I UNDERSTAND CERTAIN SYSTEMS ARE WIRED WITH AN ILS OVERRIDE RELAY, BUT MINE IS NOT (FACTORY INSTALLED SYSTEMS BY XX ACFT CORP). I AM NOT SURE WHETHER THE MANUFACTURER PROVIDES SUCH AN ILS SIGNAL TO EXTERNAL DEVICES. MY ASSUMPTION WAS THAT THE G/S POINTERS WERE BURIED IN THE BOTTOM OF THE DISPLAY BECAUSE WE WERE IN A SLAMDUNK, ABOVE THE G/S APCH. I DSNDED AGGRESSIVELY TO REACH THE G/S. DSNT CONTINUED UNTIL I BEGAN TO LEVEL OFF AT 500' MSL, REACHING ABOUT 400' MSL (DH IS 437' MSL). STILL IMC, I NOTED WE WERE SEVERAL MI FROM THE FIELD AND THE G/S HAD NEVER APPEARED. I HAD FIXATED ON GETTING A G/S AND WASN'T X-CHKING ALT. I INSTITUTED AN IMMEDIATE CLB, DECLARING A MISSED APCH. OUR ESTIMATED POS AT THE MISS WAS JUST INSIDE THE OM (THOUGH WE NEVER HEARD IT). THE 128 DEG LORAN COURSE WOULD HAVE PUT US ABOUT 1 MI E OF THE LOC. THIS POS IS WITHIN A MI OF A RADIO TWR AT 425' MSL. ON THE RETURN VECTOR, I REALIZED THE ERROR AND THE SECOND APCH COMPLETED NORMALLY. THE UNUSUAL VECTORING BY VANDENBERG APCH, EVEN THOUGH WE WERE VMC, WAS A DISTR. IF NORMAL PROC FOR A MIL FAC IS TO VECTOR FOR A CLOSE-IN BASE LEG INTERCEPT, THEN CIVIL PLTS SHOULD BE AWARE OF THIS AND BE READY. ON THE SECOND APCH, TWR ASKED US TO RPT THE OM; WE'D ALREADY PASSED IT BEFORE THE HDOF FROM APCH WAS COMPLETED. CORRECTIVE ACTIONS: 1) IFR PROFICIENCY TRNING. THOUGH I'VE GOT PLENTY OF IFR EXPERIENCE, A FEW HRS WITH PICKY CFII OR SAFETY PLT WILL SHARPEN MY DETAIL SKILLS DURING THE APCH PHASE. MUCH OF OUR IFR TIME IS SPENT IN CRUISE AND FLYING RELATIVELY SIMPLE APCHS. FIXATION ON REACHING THE G/S WAS PROBABLY DUE TO MY MINDSET CAUSED BY THE SLAM DUNK APCH. THIS SET UP AN EXPECTATION THAT THE G/S WOULD BE REACHED, CAUSING ME TO IGNORE THE ALT XCHK DURING THE DSNT.

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.