B737 flight crew reported overshooting the assigned altitude on descent into sjc citing high workloa...

Attributes
ACN	1422931
Time
Date	201702
Local Time Of Day	1201-1800
Place
Locale Reference	SJC.Airport
State Reference	CA
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR SILCN4
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 28 Flight Crew Type 10000
Person 2
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 133
Events
Anomaly	ATC Issue All Types Deviation - Altitude Overshoot Deviation - Procedural Clearance

Narrative:

ATC threw us many late and revised clearances to our arrival/landing runway; with vectors; speed; and altitude changes. Somewhere in the many changes; aircraft automation changed to cws (control wheel steering) pitch. We had finally cleared up a confusing clearance by ATC (bottom line was to descend to 7000; then via the remainder of the silcn 4 RNAV arrival). The change to cws pitch was noted and verbalized by the pm at around 7400 MSL; but obviously not clear enough to register with the PF. After another radio call and coordination in the cockpit; the pm clearly verbalized to the PF that the aircraft had descended to around 6600/6700 ft. The PF made a correction and we leveled at 7000. ATC did not say anything; and I do not believe there was any conflict with other traffic.I just completed aqp (advanced qualification program) in january and credit that with helping trap the error. The emphasis on terrain awareness; distraction management; and to slow down was exactly the situation we found ourselves in. I firmly believe our current training is exactly what is needed to raise awareness. While this did seem like an exaggerated case of distractions; it is what it is; and we need to deal with it. Distractions; both internal and external; can diminish communication; and I (we) need to be more aware of that dynamic.

Original NASA ASRS Text

Title: B737 flight crew reported overshooting the assigned altitude on descent into SJC citing high workload and a lack of FMC mode awareness as contributing.

Narrative: ATC threw us many late and revised clearances to our arrival/landing runway; with vectors; speed; and altitude changes. Somewhere in the many changes; aircraft automation changed to CWS (Control Wheel Steering) Pitch. We had finally cleared up a confusing clearance by ATC (bottom line was to descend to 7000; then via the remainder of the SILCN 4 RNAV Arrival). The change to CWS Pitch was noted and verbalized by the PM at around 7400 MSL; but obviously not clear enough to register with the PF. After another radio call and coordination in the cockpit; the PM clearly verbalized to the PF that the aircraft had descended to around 6600/6700 ft. The PF made a correction and we leveled at 7000. ATC did not say anything; and I do not believe there was any conflict with other traffic.I just completed AQP (Advanced Qualification Program) in January and credit that with helping trap the error. The emphasis on terrain awareness; distraction management; and to slow down was exactly the situation we found ourselves in. I firmly believe our current training is exactly what is needed to raise awareness. While this did seem like an exaggerated case of distractions; it is what it is; and we need to deal with it. Distractions; both internal and external; can diminish communication; and I (we) need to be more aware of that dynamic.

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.

B737 flight crew reported overshooting the assigned altitude on descent into sjc citing high workload and a lack of FMC mode awareness as contributing.