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A B767-300 flight crew suffered autoflight anomalies on descent to oak. An airspeed deviation and failure to meet a crossing restriction resulted.
| Attributes | |
| ACN | 885823 |
| Time | |
| Date | 201004 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | OAK.Airport |
| State Reference | CA |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Route In Use | Other MADWIN FOUR |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types |
Narrative:
[We were] cleared the madwin four arrival to oak. Cruise descent from FL280 to cross sharr at 12;000 feet as per arrival; aircraft in VNAV/LNAV and center autopilot. Aircraft initially intercepted VNAV path to cross sharr at 12;000 feet; which was entered in the FMC and the MCP. Shortly thereafter we were advised by nct that it appeared we would not make the crossing restriction. I initiated a more rapid descent using speed intervene and speed brakes extended to make the altitude restriction. The aircraft increased nose down pitch and increased speed and rate of descent; it failed to capture the speed and exceeded vmo; I reduced speed commanded via the bug to slow aircraft which was very slow to respond. ATC re-cleared us to 10;000 feet prior to reaching sharr and requested we decrease our rate of descent. When later cleared to descend to 8;000 feet with VNAV selected the airspeed bug drove back to 240 knots; but the aircraft commenced descent without slowing. Disconnected auto flight systems and manually slowed aircraft and then continued descent; once stabilized I re-engaged center auto pilot and VNAV. Item entered in aircraft log.
Original NASA ASRS Text
Title: A B767-300 flight crew suffered autoflight anomalies on descent to OAK. An airspeed deviation and failure to meet a crossing restriction resulted.
Narrative: [We were] cleared the MADWIN FOUR arrival to OAK. Cruise descent from FL280 to cross SHARR at 12;000 feet as per arrival; aircraft in VNAV/LNAV and center autopilot. Aircraft initially intercepted VNAV path to cross SHARR at 12;000 feet; which was entered in the FMC and the MCP. Shortly thereafter we were advised by NCT that it appeared we would not make the crossing restriction. I initiated a more rapid descent using speed intervene and speed brakes extended to make the altitude restriction. The aircraft increased nose down pitch and increased speed and rate of descent; it failed to capture the speed and exceeded VMO; I reduced speed commanded via the bug to slow aircraft which was very slow to respond. ATC re-cleared us to 10;000 feet prior to reaching SHARR and requested we decrease our rate of descent. When later cleared to descend to 8;000 feet with VNAV selected the airspeed bug drove back to 240 knots; but the aircraft commenced descent without slowing. Disconnected auto flight systems and manually slowed aircraft and then continued descent; once stabilized I re-engaged center auto pilot and VNAV. Item entered in aircraft log.
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.