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B737-800 pilot reported they diverted to an alternate airport after experiencing degraded flight data information.
| Attributes | |
| ACN | 1321426 |
| Time | |
| Date | 201512 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Air Data Computer |
| Person 1 | |
| Function | Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Track / Heading All Types |
Narrative:
About 3 hours into cruise first officer's pfd display started to give erroneous information including groundspeed; winds; vertical speed indications and warning flags. We also noticed all three attitude indicators showed a slight left bank. There were no other warning lights until about 20 minutes later the 'fault' light for the right inertial reference system (IRS) came on. As this progressed it was apparent that our navigation was beginning to degrade because ATC said we were still heading in the right direction; but slightly off course. Eventually we completely lost the first officer's pfd attitude display and both autopilots. Given the distance to our destination; weather; night time; degraded instrumentation and no autopilots; we decided to [advise ATC] and divert to [a nearby alternate] where the weather was clear. During descent and approach it became apparent yaw damper was inoperative also. Finally during rollout the stick shaker activated.
Original NASA ASRS Text
Title: B737-800 pilot reported they diverted to an alternate airport after experiencing degraded flight data information.
Narrative: About 3 hours into cruise First Officer's PFD display started to give erroneous information including groundspeed; winds; vertical speed indications and warning flags. We also noticed all three attitude indicators showed a slight left bank. There were no other warning lights until about 20 minutes later the 'Fault' light for the right Inertial Reference System (IRS) came on. As this progressed it was apparent that our navigation was beginning to degrade because ATC said we were still heading in the right direction; but slightly off course. Eventually we completely lost the First Officer's PFD attitude display and both autopilots. Given the distance to our destination; weather; night time; degraded instrumentation and no autopilots; we decided to [advise ATC] and divert to [a nearby alternate] where the weather was clear. During descent and approach it became apparent yaw damper was inoperative also. Finally during rollout the stick shaker activated.
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.