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An MD80 flight crew reported losing the autopilot and autothrottles when a circuit breaker popped and 'mach trim inop' and 'yaw damper off' lights illuminated less than an hour from arrival. They declared an emergency and landed at destination.
| Attributes | |
| ACN | 973392 |
| Time | |
| Date | 201109 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZFW.ARTCC |
| State Reference | TX |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | MD-80 Series (DC-9-80) Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autoflight System |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
At FL330; about 50 minutes from landing; a circuit breaker (circuit breaker) popped. Our autopilot and auto-throttles kicked off. 'Mach trim inoperative' and 'yaw damp off' lights came on. We lost our altitude window on the dfgp. The vertical speed wheel and airspeed selector on the dfgp became inoperative. I talked to [maintenance; but] they could not help. The only information I could find in the QRH was a mach trim inoperative procedure that really did not fit this problem other than telling us not to exceed .78 mach. About the same time I was talking to [maintenance]; I told the first officer; who was the pilot flying; to descend to get out of rvsm airspace. ATC gave us a clearance to descend to FL270. We then declared an emergency and were cleared direct to [the] airport. I then contacted dispatch and informed them of our situation. We landed in VFR conditions without incident.
Original NASA ASRS Text
Title: An MD80 flight crew reported losing the autopilot and autothrottles when a circuit breaker popped and 'mach trim inop' and 'yaw damper off' lights illuminated less than an hour from arrival. They declared an emergency and landed at destination.
Narrative: At FL330; about 50 minutes from landing; a circuit breaker (CB) popped. Our autopilot and auto-throttles kicked off. 'Mach trim INOP' and 'yaw damp off' lights came on. We lost our altitude window on the DFGP. The vertical speed wheel and airspeed selector on the DFGP became INOP. I talked to [Maintenance; but] they could not help. The only information I could find in the QRH was a mach trim INOP procedure that really did not fit this problem other than telling us not to exceed .78 mach. About the same time I was talking to [Maintenance]; I told the First Officer; who was the pilot flying; to descend to get out of RVSM airspace. ATC gave us a clearance to descend to FL270. We then declared an emergency and were cleared direct to [the] airport. I then contacted Dispatch and informed them of our situation. We landed in VFR conditions without incident.
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.