A B737-700 autopilot failed to capture the snead 7 11;000 ft tarrk constraint event though it was in...

Attributes
ACN	1028293
Time
Date	201208
Local Time Of Day	0601-1200
Place
Locale Reference	LAS.Airport
State Reference	NV
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID SHEAD RNAV
Flight Plan	IFR
Component
Aircraft Component	Altitude Hold/Capture
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 135
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

Event occurred on shead RNAV departure from runway 25R at las. We had selected LNAV before takeoff roll and 7;000 ft selected in altitude window. Clearance limit was FL190 with all the depicted altitude restrictions. Just leaving roppr at 7;000 ft (altitude hold); departure told us to delete the roppr restriction (we'd already met) and the mddog restriction at 9;000 ft. We deleted the mddog altitude on the CDU and selected FL190 in the altitude window. We then selected VNAV and VNAV speed was on the scoreboard. The next fix; tarrk; was a magenta bold 11;000 ft. Neither one of us caught the aircraft climb through until about 11.4K; at which time ATC asked why we weren't complying with the taark restriction. We descended from approximately 11.6K to 11;000 ft. Both of us didn't understand why the aircraft did not level at 11;000 ft. Again; you can't monitor enough in dynamic flight. We could have selected 11K in the altitude window; but we felt we made no system errors. [Should have had] more intensive monitoring of navigation and autopilot systems during dynamic flight by both crew members.

Original NASA ASRS Text

Title: A B737-700 autopilot failed to capture the SNEAD 7 11;000 FT TARRK constraint event though it was in the FMS with FL190 in the MCP.

Narrative: Event occurred on SHEAD RNAV Departure from Runway 25R at LAS. We had selected LNAV before takeoff roll and 7;000 FT selected in altitude window. Clearance limit was FL190 with all the depicted altitude restrictions. Just leaving ROPPR at 7;000 FT (Altitude Hold); Departure told us to delete the ROPPR restriction (we'd already met) and the MDDOG restriction at 9;000 FT. We deleted the MDDOG altitude on the CDU and selected FL190 in the altitude window. We then selected VNAV and VNAV speed was on the scoreboard. The next fix; TARRK; was a magenta BOLD 11;000 FT. Neither one of us caught the aircraft climb through until about 11.4K; at which time ATC asked why we weren't complying with the TAARK restriction. We descended from approximately 11.6K to 11;000 FT. Both of us didn't understand why the aircraft did not level at 11;000 FT. Again; you can't monitor enough in dynamic flight. We could have selected 11K in the altitude window; but we felt we made no system errors. [Should have had] more intensive monitoring of NAV and autopilot systems during dynamic flight by both crew members.

Data retrieved from NASA's ASRS site as of July 2013 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.

A B737-700 autopilot failed to capture the snead 7 11;000 ft tarrk constraint event though it was in the FMS with FL190 in the MCP.