COURSE DEV USING OMEGA NAV.

Narrative

ENRTE FROM BOS TO DFW; WE WERE CRUISING AT FL350 AND USING OMEGA AS PRIMARY NAV. PASSING OVERHEAD LANCASTER (LRP) WE VERIFIED OUR POS WITH THE OMEGA AT XX53Z WITH 37900 LBS OF FUEL. PASSING LRP 11 NM OUTBOUND WE VERIFIED THE OUTBOUND TRACK ON J6 TOWARD MARTINSBURG (MRB). BY 45 NM SW OF LRP WE WERE 7-10 NM S OF COURSE. ZNY (FREQ 133.475) CALLED US S OF COURSE AND GAVE US A VECTOR TO INTERCEPT J6 INTO MRB. IN A PERIOD OF 3-4 MINS; THE OMEGA HAD A 7-10 NM ERROR. WE CORRECTED BACK ON COURSE USING VOR/DME. OVERHEAD MRB; VERIFIED BY VOR/DME; WE PERFORMED AN ONS PRECISION POS UPDATE IAW THE POM. THE OMEGA POS WAS 10 NM N OF OUR ACTUAL POS (MRB COORDINATES ARE N3923.1 W7750.9. OMEGA COORDINATES SHOWED N3933.3 W7752.3. AFTER WE UPDATED THE OMEGA AT MRB; WE USED IT FOR NAV AGAIN; MONITORING IT VERY CLOSELY. IT FUNCTIONED NORMALLY AFTER THE UPDATE. WE CALLED FLT CTL DISPATCHER AND ADVISED HIM OF THE OMEGA ANOMALY BTWN LRP AND MRB AND REQUESTED HE ISSUE A NOTAM TO ADVISE OUR OMEGA USERS OF THE ANOMALY SINCE THE OMEGA WORKED NORMALLY AFTER MRB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CALLBACK WAS ACCOMPLISHED TO DETERMINE IF PLT HAD EXPERIENCE AND COMPETENCY TO OPERATE THE OMEGA SYS. RPTR HAD A TOTAL OF 7 YRS EXPERIENCE WITH THE OMEGA SYS. HE HAD A DISTRUST OF THE SYS WHICH CAUSED HIM TO XCHK AND UPDATE FREQUENTLY. HE HAD NEVER HAD AS GREAT A COURSE DEV AS IN THIS INSTANCE. HE NEVER CHKED HIS VLF PAGES FOR WEAK PROPAGATION AS HE NEVER GOT A WARNING LIGHT THAT PROPAGATION MIGHT BE A PROB. THE ACFT ONLY HAD 1 SET ON BOARD SO THERE WAS NO CHANCE TO SEE OR COMPARE WITH ANOTHER SET IF THERE WAS A DIVERGENCE BTWN 2 SETS. PLT VERIFIED OMEGA WAS LOADED PROPERLY WITH THE FO PRIOR TO DEP. POS WAS CHKED OVER THE VOR PRIOR TO THE COURSE DEV. AFTER XING THE VOR THE ACFT HDG CHANGED MORE THAN WHAT WAS REQUIRED; IT WAS A GRADUAL CHANGE OF 2-3 DEGS OF BANK; NOT NOTICEABLE BY THE FLC. AFTER FLYING 42 MI THE ACFT WAS 10 MI OF COURSE. CTR CALLED AND GAVE THEM A HDG INTO THE NEXT WAYPOINT. OMEGA WAS UPDATED AT THE NEXT WAYPOINT AND FROM THEREAFTER; IT WAS ALWAYS ON TRACK. RPTR'S CHIEF PLT ACCUSED HIM OF MAKING A OPERATIONAL ERROR WITH THE QUIP. RPTR STATED TO HIM; THAT IF HE HADN'T USED THE OMEGA PROPERLY HE WOULD HAVE FILED THE ASRS RPT AND NOT HAVE SAID ANYTHING ABOUT IT TO THE COMPANY. HE DID BOTH RPTS AS HE WAS UPSET ABOUT THE OMEGA PERFORMANCE. RPTR IS CONVINCED HE DID NOTHING WRONG IN OPERATING THE OMEGA.