Narrative:

I was being vectored for the VOR/DME runway 9 approach into ryy; when I was vectored through the final approach course; which was indicated on my VOR course needle. Atl approach asked; which approach I was doing; and I responded that I wanted the VOR approach; and they responded by saying; 'sorry; I just sent you through final; but I guess you see that.' I replied that I did see it. They turned me to a heading of 090 degrees; and intercepted the final approach course. Then I was cleared for the VOR/DME runway 9 approach; maintain 3000 ft until established. Approach came back on; and said that I appeared to be left of course; and asked if I concurred. My course needle was centered; so I did not concur. They asked me to turn right; which I did; and my needle didn't change; even though approach told me I was on course. I had a VFR-only GPS on board; so I began to look to that for backup guidance; since I no longer fully trusted my VOR. I was past the FAF; on course; so I began my descent to the MDA. I began to break out at around 1900 ft MSL; which in hindsight was my MDA; but I had looked over the ILS or localizer approach into runway 27 also; and I had 1540 ft MSL in my head as the MDA. Since I thought I had plenty of altitude room to go; I continued to descend from 1900 ft to 1540 ft; so I could be completely clear of clouds. At that point; I had been switched to ryy tower; and the controller said; 'mooney X; altitude alert; do you have the runway in sight?' I stated that I did not; but that I had vertical contact. He asked me if I meant that I had the ground in sight; and I replied that I was in the clear; with the ground in sight; and that I could see the airport. I couldn't yet make out the runway; but I did see the beacon; and the airport environment. I quickly did acquire the runway; and I reported it in sight. I was then cleared to land. I continued to land without incident. My major mistake was to continue the approach when I was having an indication problem with my VOR/obs. I was confident in my position given the GPS; but since it was not IFR certified; I should not have trusted it. Unfortunately; the clouds at my position were lower than advertised; and I went below the published MDA attempting to stay clear of clouds once I could see the ground. Contributing to the incident was the fact that I had looked over the runway 27 approach as well; and had gotten the runway 27 MDA in my mind; which was over 300 ft lower than the MDA for the approach I was on. Factors affecting my performance were a nervousness about being IFR on 'round dials' given that I work at a regional airline flying in a glass cockpit. I haven't shot a true VOR approach without an FMS or mfd in 2 yrs; and I should get more practice doing so before I go out and shoot approachs in actual down to minimums. My theory on the VOR is that the VOR receiver installed on this aircraft is old; and isn't sensitive enough to pick up the VOR from where the rmg VOR is. Since it had been working in-flight; I believe that if I had come around for the localizer runway 27 approach; it would have worked fine given that the signal would have been strong and more precise. I should have gone missed; and gotten vectors for the localizer runway 27; circle to land runway 9; which the airport had the minimums for. Even a tailwind landing would have been safer than what I did. I learned a lot from this flight; and I appreciate the opportunity to contribute my scenario to help aviation safety.

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Original NASA ASRS Text

Title: M20 PILOT REPORTS VOR RECEIVER MALFUNCTION AND DESCENT BELOW MDA DURING VOR DME RWY 9 APPROACH TO RYY.

Narrative: I WAS BEING VECTORED FOR THE VOR/DME RWY 9 APCH INTO RYY; WHEN I WAS VECTORED THROUGH THE FINAL APCH COURSE; WHICH WAS INDICATED ON MY VOR COURSE NEEDLE. ATL APCH ASKED; WHICH APCH I WAS DOING; AND I RESPONDED THAT I WANTED THE VOR APCH; AND THEY RESPONDED BY SAYING; 'SORRY; I JUST SENT YOU THROUGH FINAL; BUT I GUESS YOU SEE THAT.' I REPLIED THAT I DID SEE IT. THEY TURNED ME TO A HDG OF 090 DEGS; AND INTERCEPTED THE FINAL APCH COURSE. THEN I WAS CLRED FOR THE VOR/DME RWY 9 APCH; MAINTAIN 3000 FT UNTIL ESTABLISHED. APCH CAME BACK ON; AND SAID THAT I APPEARED TO BE L OF COURSE; AND ASKED IF I CONCURRED. MY COURSE NEEDLE WAS CTRED; SO I DID NOT CONCUR. THEY ASKED ME TO TURN R; WHICH I DID; AND MY NEEDLE DIDN'T CHANGE; EVEN THOUGH APCH TOLD ME I WAS ON COURSE. I HAD A VFR-ONLY GPS ON BOARD; SO I BEGAN TO LOOK TO THAT FOR BACKUP GUIDANCE; SINCE I NO LONGER FULLY TRUSTED MY VOR. I WAS PAST THE FAF; ON COURSE; SO I BEGAN MY DSCNT TO THE MDA. I BEGAN TO BREAK OUT AT AROUND 1900 FT MSL; WHICH IN HINDSIGHT WAS MY MDA; BUT I HAD LOOKED OVER THE ILS OR LOC APCH INTO RWY 27 ALSO; AND I HAD 1540 FT MSL IN MY HEAD AS THE MDA. SINCE I THOUGHT I HAD PLENTY OF ALT ROOM TO GO; I CONTINUED TO DSND FROM 1900 FT TO 1540 FT; SO I COULD BE COMPLETELY CLR OF CLOUDS. AT THAT POINT; I HAD BEEN SWITCHED TO RYY TWR; AND THE CTLR SAID; 'MOONEY X; ALT ALERT; DO YOU HAVE THE RWY IN SIGHT?' I STATED THAT I DID NOT; BUT THAT I HAD VERT CONTACT. HE ASKED ME IF I MEANT THAT I HAD THE GND IN SIGHT; AND I REPLIED THAT I WAS IN THE CLR; WITH THE GND IN SIGHT; AND THAT I COULD SEE THE ARPT. I COULDN'T YET MAKE OUT THE RWY; BUT I DID SEE THE BEACON; AND THE ARPT ENVIRONMENT. I QUICKLY DID ACQUIRE THE RWY; AND I RPTED IT IN SIGHT. I WAS THEN CLRED TO LAND. I CONTINUED TO LAND WITHOUT INCIDENT. MY MAJOR MISTAKE WAS TO CONTINUE THE APCH WHEN I WAS HAVING AN INDICATION PROB WITH MY VOR/OBS. I WAS CONFIDENT IN MY POS GIVEN THE GPS; BUT SINCE IT WAS NOT IFR CERTIFIED; I SHOULD NOT HAVE TRUSTED IT. UNFORTUNATELY; THE CLOUDS AT MY POS WERE LOWER THAN ADVERTISED; AND I WENT BELOW THE PUBLISHED MDA ATTEMPTING TO STAY CLR OF CLOUDS ONCE I COULD SEE THE GND. CONTRIBUTING TO THE INCIDENT WAS THE FACT THAT I HAD LOOKED OVER THE RWY 27 APCH AS WELL; AND HAD GOTTEN THE RWY 27 MDA IN MY MIND; WHICH WAS OVER 300 FT LOWER THAN THE MDA FOR THE APCH I WAS ON. FACTORS AFFECTING MY PERFORMANCE WERE A NERVOUSNESS ABOUT BEING IFR ON 'ROUND DIALS' GIVEN THAT I WORK AT A REGIONAL AIRLINE FLYING IN A GLASS COCKPIT. I HAVEN'T SHOT A TRUE VOR APCH WITHOUT AN FMS OR MFD IN 2 YRS; AND I SHOULD GET MORE PRACTICE DOING SO BEFORE I GO OUT AND SHOOT APCHS IN ACTUAL DOWN TO MINIMUMS. MY THEORY ON THE VOR IS THAT THE VOR RECEIVER INSTALLED ON THIS ACFT IS OLD; AND ISN'T SENSITIVE ENOUGH TO PICK UP THE VOR FROM WHERE THE RMG VOR IS. SINCE IT HAD BEEN WORKING INFLT; I BELIEVE THAT IF I HAD COME AROUND FOR THE LOC RWY 27 APCH; IT WOULD HAVE WORKED FINE GIVEN THAT THE SIGNAL WOULD HAVE BEEN STRONG AND MORE PRECISE. I SHOULD HAVE GONE MISSED; AND GOTTEN VECTORS FOR THE LOC RWY 27; CIRCLE TO LAND RWY 9; WHICH THE ARPT HAD THE MINIMUMS FOR. EVEN A TAILWIND LNDG WOULD HAVE BEEN SAFER THAN WHAT I DID. I LEARNED A LOT FROM THIS FLT; AND I APPRECIATE THE OPPORTUNITY TO CONTRIBUTE MY SCENARIO TO HELP AVIATION SAFETY.

Data retrieved from NASA's ASRS site as of January 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.