 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B757-200 flight crew noticed they had a navigation error. They continued in VFR conditions to their destination with center help.
| Attributes | |
| ACN | 868067 |
| Time | |
| Date | 201001 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Component | |
| Aircraft Component | INS / IRS / IRU |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 14000 Flight Crew Type 9000 |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Experience | Flight Crew Last 90 Days 240 Flight Crew Total 15000 Flight Crew Type 6000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Got several 'IRS navigation only' messages on EICAS in flight. Had 'GPWS terrain' message after take-off in VMC. FMC's indicated auto updating to NAVAID (tuning). Saw that RDMI HSI VOR raw data was 6 miles (less) than FMC fix page when performing FMC fix (dist) check. Asked center about DME at FL330. Matched RDMI VOR HSI raw data. Both FMC's off by 6 miles. Informed them about possible navigation degradation. Hand off to next center; had same problem. Radar vectors to destination; rest of flight normal. Entire flight in VMC. Maintenance changed bad left IRS unit.
Original NASA ASRS Text
Title: A B757-200 Flight Crew noticed they had a navigation error. They continued in VFR conditions to their destination with Center help.
Narrative: Got several 'IRS NAV only' messages on EICAS in flight. Had 'GPWS terrain' message after take-off in VMC. FMC's indicated auto updating to NAVAID (tuning). Saw that RDMI HSI VOR raw data was 6 miles (less) than FMC fix page when performing FMC fix (dist) check. Asked Center about DME at FL330. Matched RDMI VOR HSI raw data. Both FMC's off by 6 miles. Informed them about possible NAV degradation. Hand off to next Center; had same problem. Radar vectors to destination; rest of flight normal. Entire flight in VMC. Maintenance changed bad left IRS unit.
Data retrieved from NASA's ASRS site as of April 2012 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.