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B737-ng captain reported diverting to an alternate airport experiencing dual FMC failure.
| Attributes | |
| ACN | 1410362 |
| Time | |
| Date | 201612 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 10000 Flight Crew Type 2500 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe |
Narrative:
On preflight; captain had momentarily loss of FMC; after a couple seconds FMC worked ok. On taxi out to runway in first officer's FMC went inoperative. Taxied back to gate. Mechanics worked on fmcs and finally signed off that they were both good to go. Takeoff to cruise altitude of FL330 uneventful. Approximately 1.5 hours into the first officer's FMC failed. We ran the appropriate QRH. Continued on with captain's FMC still good. Shortly after [that] captain's FMC failed; and first officer's came back. We ran appropriate QRH. This [cycle] of captain and first officer's FMC working then not working [happened several times] until both failed completely. 'GPS left invalid' flashed. Auto throttle kicked offline. Nd and pfd screens on both sides flickered for about 60 seconds then stopped. Coordinated with dispatch; decision made to divert into [an alternate]; due to primary nav system loss; destination [weather] IMC; rain; sleet; gusty winds; destination airport high density aircraft; heavy cockpit work load; and unsure of what emergency really was outside of dual FMC failure. With screens flickering we didn't know if there could be a compounded emergency. [ATC was advised]. Vectors provided to uneventful visual made by first officer. Waited 1.5 hours on tarmac till a gate was provided.
Original NASA ASRS Text
Title: B737-NG Captain reported diverting to an alternate airport experiencing dual FMC failure.
Narrative: On preflight; Captain had momentarily loss of FMC; after a couple seconds FMC worked OK. On taxi out to runway in FO's FMC went inoperative. Taxied back to gate. Mechanics worked on FMCs and finally signed off that they were both good to go. Takeoff to cruise altitude of FL330 uneventful. Approximately 1.5 hours into the FO's FMC failed. We ran the appropriate QRH. Continued on with Captain's FMC still good. Shortly after [that] Captain's FMC failed; and FO's came back. We ran appropriate QRH. This [cycle] of Captain and FO's FMC working then not working [happened several times] until both failed completely. 'GPS left invalid' flashed. Auto throttle kicked offline. ND and PFD screens on both sides flickered for about 60 seconds then stopped. Coordinated with Dispatch; decision made to divert into [an alternate]; due to primary Nav system loss; destination [weather] IMC; rain; sleet; gusty winds; destination airport high density aircraft; heavy cockpit work load; and unsure of what emergency really was outside of dual FMC failure. With screens flickering we didn't know if there could be a compounded emergency. [ATC was advised]. Vectors provided to uneventful visual made by FO. Waited 1.5 hours on tarmac till a gate was provided.
Data retrieved from NASA's ASRS site 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.