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A DC8 freighter aircraft reports that it was off course. The rptrs suspect an aircraft equipment problem faulty INS update passing the APU VOR.
| Attributes | |
| ACN | 354250 |
| Time | |
| Date | 199611 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : apu |
| State Reference | FO |
| Altitude | msl bound lower : 27000 msl bound upper : 27000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : rctp |
| Operator | common carrier : air carrier |
| Make Model Name | DC-8F |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | departure other enroute : pacific enroute airway : b576 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 7200 flight time type : 2000 |
| ASRS Report | 354250 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi pilot : flight engineer |
| Experience | flight time last 90 days : 100 flight time total : 12000 flight time type : 3000 |
| ASRS Report | 353803 |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : clearance other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : overcame equipment problem flight crew : returned to intended course or assigned course flight crew : became reoriented |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Taipei center reported showing us right on course 5-6 mi. We were navigating with INS and backing up with VOR. At that time our VOR radial was 037 degrees. We had updated INS with APU VOR prior to report from center and suspect update from APU VOR was bad. We corrected back left off cju VOR and the update function worked fine the rest of the trip. It appears we had an unreliable signal from APU, based on the fact I showed us left of course and radar showed us right of course. We also noticed 2 aircraft pass opposite direction off to our left to confirm radar's indication of our position.
Original NASA ASRS Text
Title: A DC8 FREIGHTER ACFT RPTS THAT IT WAS OFF COURSE. THE RPTRS SUSPECT AN ACFT EQUIP PROB FAULTY INS UPDATE PASSING THE APU VOR.
Narrative: TAIPEI CTR RPTED SHOWING US RIGHT ON COURSE 5-6 MI. WE WERE NAVING WITH INS AND BACKING UP WITH VOR. AT THAT TIME OUR VOR RADIAL WAS 037 DEGS. WE HAD UPDATED INS WITH APU VOR PRIOR TO RPT FROM CTR AND SUSPECT UPDATE FROM APU VOR WAS BAD. WE CORRECTED BACK L OFF CJU VOR AND THE UPDATE FUNCTION WORKED FINE THE REST OF THE TRIP. IT APPEARS WE HAD AN UNRELIABLE SIGNAL FROM APU, BASED ON THE FACT I SHOWED US L OF COURSE AND RADAR SHOWED US R OF COURSE. WE ALSO NOTICED 2 ACFT PASS OPPOSITE DIRECTION OFF TO OUR L TO CONFIRM RADAR'S INDICATION OF OUR POS.
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.