Narrative:

I was on IFR flight from santa monica to santa barbara. On the VOR approach to runway 25 at sba, I was instructed to cross kwang intersection at 4000 ft and cleared for the approach. When my #2 navigation indicated we were at kwang, I began to descend. Sba approach wanted to know why I started to descend. I told ATC we had passed kwang, but ATC said we were just getting there and should have still been at 4000 ft. I told ATC that there had been occasional problems with the #2 navigation on this rental aircraft -- the needle would stick or be sluggish or inaccurate. It had been reported weeks earlier, but numerous pilots had not reported any problem and I do not believe it was ever repaired. I performed a vot check at smo before departure and the vors were operational, although #2 appeared somewhat sluggish but perfectly usable. We were then given vectors to the sba final approach course -- the 099 degree radial off the gaviota VOR. Even when tuned in and doublechked, ATC said we were about 1 mi left of course. The navs on board (#1 and #2) indicated we were right on course. Anyway, not sure whether the problem was caused by a faulty navigation on the plane, a problem with ATC's radar, or a combination of both. Flight landed without incident.

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Original NASA ASRS Text

Title: A PA28-161 DSNDS BEFORE XING THE KWANG INTXN WHEN HIS #2 VOR INDICATES THE SPECIFIED FIX TOO EARLY E OF SBA, CA.

Narrative: I WAS ON IFR FLT FROM SANTA MONICA TO SANTA BARBARA. ON THE VOR APCH TO RWY 25 AT SBA, I WAS INSTRUCTED TO CROSS KWANG INTXN AT 4000 FT AND CLRED FOR THE APCH. WHEN MY #2 NAV INDICATED WE WERE AT KWANG, I BEGAN TO DSND. SBA APCH WANTED TO KNOW WHY I STARTED TO DSND. I TOLD ATC WE HAD PASSED KWANG, BUT ATC SAID WE WERE JUST GETTING THERE AND SHOULD HAVE STILL BEEN AT 4000 FT. I TOLD ATC THAT THERE HAD BEEN OCCASIONAL PROBS WITH THE #2 NAV ON THIS RENTAL ACFT -- THE NEEDLE WOULD STICK OR BE SLUGGISH OR INACCURATE. IT HAD BEEN RPTED WKS EARLIER, BUT NUMEROUS PLTS HAD NOT RPTED ANY PROB AND I DO NOT BELIEVE IT WAS EVER REPAIRED. I PERFORMED A VOT CHK AT SMO BEFORE DEP AND THE VORS WERE OPERATIONAL, ALTHOUGH #2 APPEARED SOMEWHAT SLUGGISH BUT PERFECTLY USABLE. WE WERE THEN GIVEN VECTORS TO THE SBA FINAL APCH COURSE -- THE 099 DEG RADIAL OFF THE GAVIOTA VOR. EVEN WHEN TUNED IN AND DOUBLECHKED, ATC SAID WE WERE ABOUT 1 MI L OF COURSE. THE NAVS ON BOARD (#1 AND #2) INDICATED WE WERE RIGHT ON COURSE. ANYWAY, NOT SURE WHETHER THE PROB WAS CAUSED BY A FAULTY NAV ON THE PLANE, A PROB WITH ATC'S RADAR, OR A COMBINATION OF BOTH. FLT LANDED WITHOUT INCIDENT.

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.