Narrative:

First officer was the PF and at 62 DME from lhy we turned to 246 degrees to track the 066 degree radial for V408. Once established on the correct heading, both VOR course indicators showed the course to be about 6 degrees to the south. The obs was moving randomly right to left about 2-3 degrees. The first officer set up a 30 degree intercept and a few mins later we had centered indications. However, the obs was still randomly fluctuating +/-2-4 degrees left and right of course. Center then called us and told us we were going off course and asked us what radial we were on. I replied we were showing on course. Center put us on a heading back to the north. After turning, I verified the correct settings on both radios and our setup was correct. At this time the VOR started showing larger course fluctuations and mostly to the north. Center informed us we were back on the airway and now we were about 40-45 DME from the VOR and the course was centered again. I informed center we had 2 independent navigation radios, both of which showed us on course earlier and I think that the VOR signal was misleading and inaccurate. It could be some interference from something we fly over right at that point (62 DME on the 066 degree radial) because the signal was more accurate as we got closer. Center's response was 'whatever.' the VOR check was current on the airplane and both radios worked fine. In the future, I am going to be more skeptical when the course needle is fluctuating and probably maintain my heading until the random movements subside and not be so aggressive to get established on an inaccurate course indication.

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Original NASA ASRS Text

Title: BE02 CREW HAD A BAD NAV SIGNAL FROM A VOR.

Narrative: FO WAS THE PF AND AT 62 DME FROM LHY WE TURNED TO 246 DEGS TO TRACK THE 066 DEG RADIAL FOR V408. ONCE ESTABLISHED ON THE CORRECT HDG, BOTH VOR COURSE INDICATORS SHOWED THE COURSE TO BE ABOUT 6 DEGS TO THE S. THE OBS WAS MOVING RANDOMLY R TO L ABOUT 2-3 DEGS. THE FO SET UP A 30 DEG INTERCEPT AND A FEW MINS LATER WE HAD CTRED INDICATIONS. HOWEVER, THE OBS WAS STILL RANDOMLY FLUCTUATING +/-2-4 DEGS L AND R OF COURSE. CTR THEN CALLED US AND TOLD US WE WERE GOING OFF COURSE AND ASKED US WHAT RADIAL WE WERE ON. I REPLIED WE WERE SHOWING ON COURSE. CTR PUT US ON A HDG BACK TO THE N. AFTER TURNING, I VERIFIED THE CORRECT SETTINGS ON BOTH RADIOS AND OUR SETUP WAS CORRECT. AT THIS TIME THE VOR STARTED SHOWING LARGER COURSE FLUCTUATIONS AND MOSTLY TO THE N. CTR INFORMED US WE WERE BACK ON THE AIRWAY AND NOW WE WERE ABOUT 40-45 DME FROM THE VOR AND THE COURSE WAS CTRED AGAIN. I INFORMED CTR WE HAD 2 INDEPENDENT NAV RADIOS, BOTH OF WHICH SHOWED US ON COURSE EARLIER AND I THINK THAT THE VOR SIGNAL WAS MISLEADING AND INACCURATE. IT COULD BE SOME INTERFERENCE FROM SOMETHING WE FLY OVER RIGHT AT THAT POINT (62 DME ON THE 066 DEG RADIAL) BECAUSE THE SIGNAL WAS MORE ACCURATE AS WE GOT CLOSER. CTR'S RESPONSE WAS 'WHATEVER.' THE VOR CHK WAS CURRENT ON THE AIRPLANE AND BOTH RADIOS WORKED FINE. IN THE FUTURE, I AM GOING TO BE MORE SKEPTICAL WHEN THE COURSE NEEDLE IS FLUCTUATING AND PROBABLY MAINTAIN MY HDG UNTIL THE RANDOM MOVEMENTS SUBSIDE AND NOT BE SO AGGRESSIVE TO GET ESTABLISHED ON AN INACCURATE COURSE INDICATION.

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.