Narrative:

We left ord for lga by routing out J146. I was being given a line check by a check airman. As we left ord I did an accuracy check of our omega and coupled it to the autoplt. As we crossed giper (gij). I did a position check and set the vors to the outbound radial (089 degrees) toward our next fix of ideas. As we proceeded outbound, we noticed the omega taking us north of J146. Noting the discrepancy, we began to check coordinates and proper routing. While trouble-shooting the omega position and accuracy, we selected a 110 degree heading to reintercept the airway. ATC called shortly thereafter and suggested a 120 degree heading to reintercept, and stated that we were 7 mi north of centerline. The only discrepancy noted was an omega wind report of 358 degrees at 107 KTS. We feel the wind was erroneous, and the omega computed a track angle based on wrong information. Shortly after our intercept, the omega showed winds at 40 KTS. No conflict was reported either by ATC or TCASII. As the deviation happened rather quickly, we feel the wind report in the omega generated the error. As it was a line check, there was much discussion on the flight deck. Briefings should be left for after the trip, and not during it.

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Original NASA ASRS Text

Title: DEV FROM CLRNC RTE. ACR CREW ALLOWS ACFT TO DRIFT OFF COURSE WHEN OMEGA NAV EQUIP MALFUNCTIONS EVEN THOUGH THE PROPER COURSE IS DISPLAYED ON THE VHF NAV RADIO.

Narrative: WE LEFT ORD FOR LGA BY ROUTING OUT J146. I WAS BEING GIVEN A LINE CHK BY A CHK AIRMAN. AS WE LEFT ORD I DID AN ACCURACY CHK OF OUR OMEGA AND COUPLED IT TO THE AUTOPLT. AS WE CROSSED GIPER (GIJ). I DID A POS CHK AND SET THE VORS TO THE OUTBOUND RADIAL (089 DEGS) TOWARD OUR NEXT FIX OF IDEAS. AS WE PROCEEDED OUTBOUND, WE NOTICED THE OMEGA TAKING US N OF J146. NOTING THE DISCREPANCY, WE BEGAN TO CHK COORDINATES AND PROPER ROUTING. WHILE TROUBLE-SHOOTING THE OMEGA POS AND ACCURACY, WE SELECTED A 110 DEG HDG TO REINTERCEPT THE AIRWAY. ATC CALLED SHORTLY THEREAFTER AND SUGGESTED A 120 DEG HDG TO REINTERCEPT, AND STATED THAT WE WERE 7 MI N OF CTRLINE. THE ONLY DISCREPANCY NOTED WAS AN OMEGA WIND RPT OF 358 DEGS AT 107 KTS. WE FEEL THE WIND WAS ERRONEOUS, AND THE OMEGA COMPUTED A TRACK ANGLE BASED ON WRONG INFO. SHORTLY AFTER OUR INTERCEPT, THE OMEGA SHOWED WINDS AT 40 KTS. NO CONFLICT WAS RPTED EITHER BY ATC OR TCASII. AS THE DEV HAPPENED RATHER QUICKLY, WE FEEL THE WIND RPT IN THE OMEGA GENERATED THE ERROR. AS IT WAS A LINE CHK, THERE WAS MUCH DISCUSSION ON THE FLT DECK. BRIEFINGS SHOULD BE LEFT FOR AFTER THE TRIP, AND NOT DURING IT.

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.