A B767-300 flight crew suffered autoflight anomalies on descent to oak. An airspeed deviation and fa...

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.

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

A B767-300 flight crew suffered autoflight anomalies on descent to oak. An airspeed deviation and failure to meet a crossing restriction resulted.