Narrative:

After a temporary tour of duty, I was returning to base in a single F-16C. The sortie included navigation and instrument procedures only, no tactical training was involved. My clearance route included J191 from patuxent VORTAC to smyrna VORTAC. I was traveling to the northeast on the jet route at FL410. After passing patuxent VORTAC, my TACAN bearing pointer continued to swing plus and minus 20 degree in the direction of pxt for several mi. I switched to INS mode in an attempt to tract the radial outbound. However, my INS must have drifted because center then called 'military flight-X, turn 20 degrees left to avoid restricted area.' I turned as directed, and then was cleared to intercept J191. However, my erratic TACAN and faulty INS information again caused me to drift off J191, and I estimate that I was 10 NM west of J191 at smyrna VORTAC when I was cleared direct to albany. I should have been more aggressive in xchking and updating my INS accuracy, so that when the TACAN became unreliable my INS data would have been good. I could have queried ATC as to my position to determine which on-board NAVAID (if either) was accurate, and I could have easily requested ATC assistance if I questioned my navaids.

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Original NASA ASRS Text

Title: NAV ERROR - THE PLT OF THIS F-16C LOST HIS TACAN AND WENT OFF COURSE AND HIS INS WAS MIS-OPERATED SO THE CTLR ASSISTED HIM.

Narrative: AFTER A TEMPORARY TOUR OF DUTY, I WAS RETURNING TO BASE IN A SINGLE F-16C. THE SORTIE INCLUDED NAV AND INST PROCS ONLY, NO TACTICAL TRAINING WAS INVOLVED. MY CLRNC RTE INCLUDED J191 FROM PATUXENT VORTAC TO SMYRNA VORTAC. I WAS TRAVELING TO THE NE ON THE JET RTE AT FL410. AFTER PASSING PATUXENT VORTAC, MY TACAN BEARING POINTER CONTINUED TO SWING PLUS AND MINUS 20 DEG IN THE DIRECTION OF PXT FOR SEVERAL MI. I SWITCHED TO INS MODE IN AN ATTEMPT TO TRACT THE RADIAL OUTBOUND. HOWEVER, MY INS MUST HAVE DRIFTED BECAUSE CTR THEN CALLED 'MIL FLT-X, TURN 20 DEGS L TO AVOID RESTRICTED AREA.' I TURNED AS DIRECTED, AND THEN WAS CLRED TO INTERCEPT J191. HOWEVER, MY ERRATIC TACAN AND FAULTY INS INFO AGAIN CAUSED ME TO DRIFT OFF J191, AND I ESTIMATE THAT I WAS 10 NM W OF J191 AT SMYRNA VORTAC WHEN I WAS CLRED DIRECT TO ALBANY. I SHOULD HAVE BEEN MORE AGGRESSIVE IN XCHKING AND UPDATING MY INS ACCURACY, SO THAT WHEN THE TACAN BECAME UNRELIABLE MY INS DATA WOULD HAVE BEEN GOOD. I COULD HAVE QUERIED ATC AS TO MY POS TO DETERMINE WHICH ON-BOARD NAVAID (IF EITHER) WAS ACCURATE, AND I COULD HAVE EASILY REQUESTED ATC ASSISTANCE IF I QUESTIONED MY NAVAIDS.

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.