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Flight crew of air carrier medium large transport aircraft deviated from assigned track due to a faulty aircraft FMC.
| Attributes | |
| ACN | 226807 |
| Time | |
| Date | 199211 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : omn |
| State Reference | FL |
| Altitude | msl bound lower : 14000 msl bound upper : 14000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zjx |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 180 flight time total : 7000 flight time type : 1000 |
| ASRS Report | 226807 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : commercial pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : clearance other anomaly other other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 30000 vertical : 0 |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
During medium large transport aircraft IRU alignment present position was entered into FMC, but the FMC would not take the new position saying 'verify position' jax airport position verified and correct. Reentered into the FMC which finally took. Somewhere between takeoff and cruise, there was a 160 NM map shift (no known reason at this time). The map shift caused us to start direct to omn VOR but the computer put the VOR 150 mi off the coast. We noticed the beach below us and on about a 120 degree heading out over the ocean and the LNAV distance to omn was too far. As we troubleshot the problem and transitioned to raw data, ZJX gave us a heading south to avoid traffic at the same altitude, opposite direction. We were never closer than 5 mi.
Original NASA ASRS Text
Title: FLC OF ACR MLG ACFT DEVIATED FROM ASSIGNED TRACK DUE TO A FAULTY ACFT FMC.
Narrative: DURING MLG ACFT IRU ALIGNMENT PRESENT POS WAS ENTERED INTO FMC, BUT THE FMC WOULD NOT TAKE THE NEW POS SAYING 'VERIFY POS' JAX ARPT POS VERIFIED AND CORRECT. REENTERED INTO THE FMC WHICH FINALLY TOOK. SOMEWHERE BTWN TKOF AND CRUISE, THERE WAS A 160 NM MAP SHIFT (NO KNOWN REASON AT THIS TIME). THE MAP SHIFT CAUSED US TO START DIRECT TO OMN VOR BUT THE COMPUTER PUT THE VOR 150 MI OFF THE COAST. WE NOTICED THE BEACH BELOW US AND ON ABOUT A 120 DEG HDG OUT OVER THE OCEAN AND THE LNAV DISTANCE TO OMN WAS TOO FAR. AS WE TROUBLESHOT THE PROBLEM AND TRANSITIONED TO RAW DATA, ZJX GAVE US A HDG S TO AVOID TFC AT THE SAME ALT, OPPOSITE DIRECTION. WE WERE NEVER CLOSER THAN 5 MI.
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.