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A B757-200 flight crew encountered multiple FMC and autoflight system anomalies during initial climb. Among other things an altitude deviation occurred when the aircraft failed to level at the altitude in the altitude select window.
| Attributes | |
| ACN | 926665 |
| Time | |
| Date | 201101 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autoflight System |
| Person 1 | |
| Function | Pilot Flying First Officer |
| Person 2 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Altitude Overshoot Deviation - Procedural Clearance |
Narrative:
During climb to 5;000 ft and heading 090 degrees we selected VNAV; flaps 5 climb power at 1;500 AGL. The autoflight system then malfunctioned with VNAV switching to climb mode then to continuous with a momentary indication of throttle hold. We then selected the right autopilot and reselected VNAV. Once again the system switched to climb mode then to continuous mode. We checked in with departure control and complied with a requested new heading of 170 degrees. With clearance to 5;000 ft whereupon the autopilot failed to capture set altitude. At 5;700; we interceded manually; disconnected the autopilot and auto throttles and descended back to 5;000 ft. ATC cleared us to climb to 16;000 ft. We selected flch and initiated a climb. When level at 16;000 ft the aircraft accelerated towards vne with flight director command bars directing a descent with 5 degrees nose down. We then deselected both flight directors. After approximately 15 minutes; systems stabilized. There were no further erroneous indications or autoflight malfunctions.
Original NASA ASRS Text
Title: A B757-200 flight crew encountered multiple FMC and autoflight system anomalies during initial climb. Among other things an altitude deviation occurred when the aircraft failed to level at the altitude in the altitude select window.
Narrative: During climb to 5;000 FT and heading 090 degrees we selected VNAV; flaps 5 climb power at 1;500 AGL. The autoflight system then malfunctioned with VNAV switching to climb mode then to continuous with a momentary indication of throttle hold. We then selected the right autopilot and reselected VNAV. Once again the system switched to climb mode then to continuous mode. We checked in with Departure Control and complied with a requested new heading of 170 degrees. With clearance to 5;000 FT whereupon the autopilot failed to capture set altitude. At 5;700; we interceded manually; disconnected the autopilot and auto throttles and descended back to 5;000 FT. ATC cleared us to climb to 16;000 FT. We selected FLCH and initiated a climb. When level at 16;000 FT the aircraft accelerated towards VNE with Flight Director Command Bars directing a descent with 5 degrees nose down. We then deselected both Flight Directors. After approximately 15 minutes; systems stabilized. There were no further erroneous indications or autoflight malfunctions.
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.