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Navigation error induced by omega failure. Reporter cites company policy and faulty maintenance as contributory.
| Attributes | |
| ACN | 147395 |
| Time | |
| Date | 199005 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : jfk |
| State Reference | NY |
| Altitude | msl bound lower : 31000 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute : atlantic enroute : other oceanic enroute airway : a23 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 130 flight time total : 3300 flight time type : 1000 |
| ASRS Report | 147395 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : critical other spatial deviation |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : became reoriented other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Flight st martin to jfk. Northbound on A23 (north of grann intersection) we noted numerous omega failures, including: 1) status annunciators-dr/VLF, 2) status display 2 only 1 omega station being received, 3) status display 4 2.3 NM estimated position error (normally 1.0-1.7), and 4) wind readout-035 degrees at 207 KTS (later increased to over 300 KTS), forecast wind 250/40. As our company operation manual gave no direction as to a solution the captain elected to divert to bermuda for repairs. Reported position doubtful to ny radio and requested clearance direct to bda. Subsequent D/right navigation very accurate to bda. Upon landing omega unit error 310 NM. Post-flight analyst revealed maintenance log book entries showing the same omega gripe the previous day (mco/jk). Maintenance subsequently replaced parts. Additional contributing factors: the flight crew had flown 30 hours in the previous 4 days (fatigue). Additionally the pilot navigating had made a plotting chart error which further confused the navigation position (in addition to the malfunctioning omega). It is not company policy for the second pilot to check the plotting chart. Everything else is checked twice and then again. With only 1 omega unit it would have been easy to get lulled into believing the incorrect position. At least some other airlines have 2 omega navigation units (a good idea).
Original NASA ASRS Text
Title: NAVIGATION ERROR INDUCED BY OMEGA FAILURE. REPORTER CITES COMPANY POLICY AND FAULTY MAINTENANCE AS CONTRIBUTORY.
Narrative: FLT ST MARTIN TO JFK. NBND ON A23 (N OF GRANN INTXN) WE NOTED NUMEROUS OMEGA FAILURES, INCLUDING: 1) STATUS ANNUNCIATORS-DR/VLF, 2) STATUS DISPLAY 2 ONLY 1 OMEGA STATION BEING RECEIVED, 3) STATUS DISPLAY 4 2.3 NM ESTIMATED POS ERROR (NORMALLY 1.0-1.7), AND 4) WIND READOUT-035 DEGS AT 207 KTS (LATER INCREASED TO OVER 300 KTS), FORECAST WIND 250/40. AS OUR COMPANY OPERATION MANUAL GAVE NO DIRECTION AS TO A SOLUTION THE CAPT ELECTED TO DIVERT TO BERMUDA FOR REPAIRS. RPTED POS DOUBTFUL TO NY RADIO AND REQUESTED CLRNC DIRECT TO BDA. SUBSEQUENT D/R NAV VERY ACCURATE TO BDA. UPON LNDG OMEGA UNIT ERROR 310 NM. POST-FLT ANALYST REVEALED MAINT LOG BOOK ENTRIES SHOWING THE SAME OMEGA GRIPE THE PREVIOUS DAY (MCO/JK). MAINT SUBSEQUENTLY REPLACED PARTS. ADDITIONAL CONTRIBUTING FACTORS: THE FLT CREW HAD FLOWN 30 HRS IN THE PREVIOUS 4 DAYS (FATIGUE). ADDITIONALLY THE PLT NAVIGATING HAD MADE A PLOTTING CHART ERROR WHICH FURTHER CONFUSED THE NAV POS (IN ADDITION TO THE MALFUNCTIONING OMEGA). IT IS NOT COMPANY POLICY FOR THE SECOND PLT TO CHK THE PLOTTING CHART. EVERYTHING ELSE IS CHKED TWICE AND THEN AGAIN. WITH ONLY 1 OMEGA UNIT IT WOULD HAVE BEEN EASY TO GET LULLED INTO BELIEVING THE INCORRECT POS. AT LEAST SOME OTHER AIRLINES HAVE 2 OMEGA NAV UNITS (A GOOD IDEA).
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.