Narrative:

We had departed dca en route to rdu. Our departure was a radar vector to the southwest. After we were turned over to center, our flight was cleared direct to hafnr intersection, then flight plan route. We were omega equipped which was the only means to go direct to hafnr. As we approached the intersection, ATC called inquiring as to WX. We were proceeding direct to hafnr intersection. We replied we were and the omega showed 1 mi to go. Center told us they showed us 10 mi south of hafnr intersection. At this point we went direct to gve using the VOR's which showed us just about dead center on course. After arrival at rdu, we accomplished an accuracy check on the omega and it showed a radial error of only 2.2 NM. Our next leg was rdu to atl which consisted of a radar vector for departure to the SID followed by a clearance present position direct to odf (foot hills) northeast of atlanta. East of odf we were cleared directly to womac intersection, 40 NM northeast of atl on the atl 041 degree radial. As we neared womac per the omega, center asked if we were going direct to womac, as they showed our position 9 mi south of womac. I decided the omega was of questionable accuracy as this was the second time it put us south of course. We were given an off course heading for flow control into atl. After gate arrival, another accuracy check was performed on the omega with a radial error of only 1.9 NM. Our company procedures require us to verify way point and coordinates for each waypoint and during flight as each waypoint is approached the coordinates and waypoints again checked. These procedures were followed during each leg. I did write up the omega system as being unreliable.the next day we again had the same aircraft and a similar off course occurred approaching the dfw area, though the error was only 5 NM south of course. The common thread in all 3 occurrences appears to be each 1 of the intxns we were cleared to, had to be manually entered into the omega during flight, and was not part of the ACARS uploaded flight plan. I do not know what if any connection there is but there must have been some sort of glitch running around. All maintenance did in atl was reinitialize the omega.

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Original NASA ASRS Text

Title: NAV DEV.

Narrative: WE HAD DEPARTED DCA ENRTE TO RDU. OUR DEP WAS A RADAR VECTOR TO THE SW. AFTER WE WERE TURNED OVER TO CTR, OUR FLT WAS CLRED DIRECT TO HAFNR INTXN, THEN FLT PLAN RTE. WE WERE OMEGA EQUIPPED WHICH WAS THE ONLY MEANS TO GO DIRECT TO HAFNR. AS WE APCHED THE INTXN, ATC CALLED INQUIRING AS TO WX. WE WERE PROCEEDING DIRECT TO HAFNR INTXN. WE REPLIED WE WERE AND THE OMEGA SHOWED 1 MI TO GO. CTR TOLD US THEY SHOWED US 10 MI S OF HAFNR INTXN. AT THIS POINT WE WENT DIRECT TO GVE USING THE VOR'S WHICH SHOWED US JUST ABOUT DEAD CTR ON COURSE. AFTER ARR AT RDU, WE ACCOMPLISHED AN ACCURACY CHK ON THE OMEGA AND IT SHOWED A RADIAL ERROR OF ONLY 2.2 NM. OUR NEXT LEG WAS RDU TO ATL WHICH CONSISTED OF A RADAR VECTOR FOR DEP TO THE SID FOLLOWED BY A CLRNC PRESENT POS DIRECT TO ODF (FOOT HILLS) NE OF ATLANTA. E OF ODF WE WERE CLRED DIRECTLY TO WOMAC INTXN, 40 NM NE OF ATL ON THE ATL 041 DEG RADIAL. AS WE NEARED WOMAC PER THE OMEGA, CTR ASKED IF WE WERE GOING DIRECT TO WOMAC, AS THEY SHOWED OUR POS 9 MI S OF WOMAC. I DECIDED THE OMEGA WAS OF QUESTIONABLE ACCURACY AS THIS WAS THE SECOND TIME IT PUT US S OF COURSE. WE WERE GIVEN AN OFF COURSE HDG FOR FLOW CTL INTO ATL. AFTER GATE ARR, ANOTHER ACCURACY CHK WAS PERFORMED ON THE OMEGA WITH A RADIAL ERROR OF ONLY 1.9 NM. OUR COMPANY PROCS REQUIRE US TO VERIFY WAY POINT AND COORDINATES FOR EACH WAYPOINT AND DURING FLT AS EACH WAYPOINT IS APCHED THE COORDINATES AND WAYPOINTS AGAIN CHKED. THESE PROCS WERE FOLLOWED DURING EACH LEG. I DID WRITE UP THE OMEGA SYS AS BEING UNRELIABLE.THE NEXT DAY WE AGAIN HAD THE SAME ACFT AND A SIMILAR OFF COURSE OCCURRED APCHING THE DFW AREA, THOUGH THE ERROR WAS ONLY 5 NM S OF COURSE. THE COMMON THREAD IN ALL 3 OCCURRENCES APPEARS TO BE EACH 1 OF THE INTXNS WE WERE CLRED TO, HAD TO BE MANUALLY ENTERED INTO THE OMEGA DURING FLT, AND WAS NOT PART OF THE ACARS UPLOADED FLT PLAN. I DO NOT KNOW WHAT IF ANY CONNECTION THERE IS BUT THERE MUST HAVE BEEN SOME SORT OF GLITCH RUNNING AROUND. ALL MAINT DID IN ATL WAS REINITIALIZE THE OMEGA.

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.