B737 captain reports descending below a published altitude during an RNAV arrival while attempting t...

Narrative:

We were cleared to descend via the RNAV arrival by approach and assigned 310 KTS as long as possible during the arrival. While descending to cross a waypoint at 15;000 ft and having previously dialed 6000 ft for the arrival (using VNAV) we descended through 15;000 ft prior to the waypoint; instead of leveling off and then continuing the descent to the next fix. Approach never mentioned the deviation. This occurred while programming the FMC to accept the higher assigned airspeed with VNAV selected. The aircraft pitched into a higher rate of descent to accept the airspeed and blew through the 15;000 ft requirement at the waypoint. Hand fly the aircraft and these errors will not happen. My first officer (as pilot monitoring) was pointing out to me that the descent rate was too great to capture and level off at 15;000 ft. I was too engrossed with trying to program the FMC that I didn't catch the error until too late. I will not let this happen again.

Original NASA ASRS Text

Title: B737 Captain reports descending below a published altitude during an RNAV arrival while attempting to program the FMC for a higher indicated airspeed as assigned by ATC.

Narrative: We were cleared to descend via the RNAV arrival by Approach and assigned 310 KTS as long as possible during the arrival. While descending to cross a waypoint at 15;000 FT and having previously dialed 6000 FT for the Arrival (using VNAV) we descended through 15;000 FT prior to the waypoint; instead of leveling off and then continuing the descent to the next fix. Approach never mentioned the deviation. This occurred while programming the FMC to accept the higher assigned airspeed with VNAV selected. The aircraft pitched into a higher rate of descent to accept the airspeed and blew through the 15;000 FT requirement at the waypoint. Hand fly the aircraft and these errors will not happen. My First Officer (as pilot monitoring) was pointing out to me that the descent rate was too great to capture and level off at 15;000 FT. I was too engrossed with trying to program the FMC that I didn't catch the error until too late. I will not let this happen again.

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	854500
Time
Date	200910
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Experience	Flight Crew Last 90 Days 262 Flight Crew Type 5600
Events
Anomaly	Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

B737 captain reports descending below a published altitude during an RNAV arrival while attempting to program the FMC for a higher indicated airspeed as assigned by ATC.