Narrative:

We departed louisville, ky, on a part 91 flight to columbus, northeast. ATC clearance read derby city 1 departure, V4 to apolo intersection, 5000 ft and runway heading. We took off runway 01 and departure assigned I believe a heading of 310 degrees. We were flying 310 degree heading when departure control assigned us to turn left to 230 degree heading climb 10000 ft and intercept V4 to apolo intersection. We proceeded with the clearance to 230 degree heading. The CDI needle was set on course and began to indicate the course was coming alive. I turned the airplane back to the right to stay on the assigned course. The CDI needle seemed to keep moving to the right. I turned the airplane according to the needle indication. A few moments later we noticed a difference between #1 and #2 CDI needles which were set on the same course off of the louisville VOR. The #2 navigation indicated we were north of course and #1 navigation indicated we were south of course. We double checked VOR frequencys and idented them. There was a difference that we verified by this time so we double checked with the GPS. It showed we were north of course 15 mi. At this time the GPS indicated to turn to apolo intersection to the south. This turn required a 90 degree turn to the left. We then turned the airplane to apolo intersection. Soon after we received a broken transmission from ATC to turn 30 degrees to the right. We tried to check about 4 or 5 times with ATC about the new heading but got no response. After we passed apolo we proceeded to our destination of columbus, northeast. We tried a few more times to contact ATC about the 30 degree turn he assigned. He then replied 'disregard.' we then continued to destination. The apparent problem with our turn back to apolo intersection after we discovered we were north of course is we penetrated the spacing of another aircraft. That is the problem at hand. But nothing was ever said to us after the incident happened. I believe we should have been notified of the problem since it was a severe problem. It wasn't brought to my attention until the next day by my chief pilot of the company I am currently employed. I believe we did our part to try to troubleshoot the navigation problem. I know this incident would not have happened if the navigation #1 was indicating properly. Also the controller should have caught that we were off course and inquired.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT ENSUES BECAUSE OF AN ACFT EQUIP PROB VOR MALFUNCTION. HDG TRACK POS DEV.

Narrative: WE DEPARTED LOUISVILLE, KY, ON A PART 91 FLT TO COLUMBUS, NE. ATC CLRNC READ DERBY CITY 1 DEP, V4 TO APOLO INTXN, 5000 FT AND RWY HDG. WE TOOK OFF RWY 01 AND DEP ASSIGNED I BELIEVE A HDG OF 310 DEGS. WE WERE FLYING 310 DEG HDG WHEN DEP CTL ASSIGNED US TO TURN L TO 230 DEG HDG CLB 10000 FT AND INTERCEPT V4 TO APOLO INTXN. WE PROCEEDED WITH THE CLRNC TO 230 DEG HDG. THE CDI NEEDLE WAS SET ON COURSE AND BEGAN TO INDICATE THE COURSE WAS COMING ALIVE. I TURNED THE AIRPLANE BACK TO THE R TO STAY ON THE ASSIGNED COURSE. THE CDI NEEDLE SEEMED TO KEEP MOVING TO THE R. I TURNED THE AIRPLANE ACCORDING TO THE NEEDLE INDICATION. A FEW MOMENTS LATER WE NOTICED A DIFFERENCE BTWN #1 AND #2 CDI NEEDLES WHICH WERE SET ON THE SAME COURSE OFF OF THE LOUISVILLE VOR. THE #2 NAV INDICATED WE WERE N OF COURSE AND #1 NAV INDICATED WE WERE S OF COURSE. WE DOUBLE CHKED VOR FREQS AND IDENTED THEM. THERE WAS A DIFFERENCE THAT WE VERIFIED BY THIS TIME SO WE DOUBLE CHKED WITH THE GPS. IT SHOWED WE WERE N OF COURSE 15 MI. AT THIS TIME THE GPS INDICATED TO TURN TO APOLO INTXN TO THE S. THIS TURN REQUIRED A 90 DEG TURN TO THE L. WE THEN TURNED THE AIRPLANE TO APOLO INTXN. SOON AFTER WE RECEIVED A BROKEN XMISSION FROM ATC TO TURN 30 DEGS TO THE R. WE TRIED TO CHK ABOUT 4 OR 5 TIMES WITH ATC ABOUT THE NEW HDG BUT GOT NO RESPONSE. AFTER WE PASSED APOLO WE PROCEEDED TO OUR DEST OF COLUMBUS, NE. WE TRIED A FEW MORE TIMES TO CONTACT ATC ABOUT THE 30 DEG TURN HE ASSIGNED. HE THEN REPLIED 'DISREGARD.' WE THEN CONTINUED TO DEST. THE APPARENT PROB WITH OUR TURN BACK TO APOLO INTXN AFTER WE DISCOVERED WE WERE N OF COURSE IS WE PENETRATED THE SPACING OF ANOTHER ACFT. THAT IS THE PROB AT HAND. BUT NOTHING WAS EVER SAID TO US AFTER THE INCIDENT HAPPENED. I BELIEVE WE SHOULD HAVE BEEN NOTIFIED OF THE PROB SINCE IT WAS A SEVERE PROB. IT WASN'T BROUGHT TO MY ATTN UNTIL THE NEXT DAY BY MY CHIEF PLT OF THE COMPANY I AM CURRENTLY EMPLOYED. I BELIEVE WE DID OUR PART TO TRY TO TROUBLESHOOT THE NAV PROB. I KNOW THIS INCIDENT WOULD NOT HAVE HAPPENED IF THE NAV #1 WAS INDICATING PROPERLY. ALSO THE CTLR SHOULD HAVE CAUGHT THAT WE WERE OFF COURSE AND INQUIRED.

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.