Narrative:

During initial climb after takeoff from 32L [we were] maintaining runway heading due to thunderstorms and moderate rain in immediate area. Altitude assignment of 5;000 ft per SID set in MCP altitude window. Passing 3;000 ft and after completing after takeoff checklist; pilot flying engaged center autopilot. I confirmed FMA annunciations heading; VNAV speed and cmd. ATC asked if we could turn to a 270-degree heading; and I turned my attention to the radar display on the nd to assess convective weather to the west of the departure path; pausing momentarily to make the 1;000 ft below assigned altitude callout when passing through 4;000 ft. Captain acknowledged. I then resumed analysis of radar returns on nd as ATC queried us once again regarding the turn to a westbound heading. Shortly thereafter; I checked my altimeter and noted that we were passing 4;900 ft with a rate of climb of 1;400 FPM. [We] crosschecked the captain's altimeter as climb continued through 5;000 ft at 1;000 plus FPM. [I] noted boxed VNAV altitude on captain's FMA. [I] verbally announced 'altitude' to captain as we approached 5;100 ft with vs of 1;000 FPM. Captain continued to monitor autoflight; but did not intervene as autopilot appeared to be reducing pitch angle with VNAV altitude displayed. At 5;200 ft I again announced 'altitude' followed by; 'we're only cleared to five thousand' and prepared to disconnect autopilot and assume control but did not at that time; autopilot remained engaged and finally captured MCP altitude; but not before overshooting our assigned altitude by about 300 ft. Neither ATC nor TCAS indicated any conflicting traffic or loss of separation. After clearing weather; we proceeded on course and resumed climb to cruise altitude with several intermediate level offs due to traffic. Center autopilot remained engaged and functioned normally. Reliability breeds complacency. It is unusual to encounter a situation in which the autoflight system fails to capture an altitude during climb or descent; especially when the appropriate FMA modes are displayed. But if it does happen; each pilot must be prepared to recognize such a malfunction and intervene to prevent an altitude bust and potential loss of separation.

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Original NASA ASRS Text

Title: B747-400 flight crew overshot assigned altitude when the autopilot was slow to initiate altitude capture.

Narrative: During initial climb after takeoff from 32L [we were] maintaining runway heading due to thunderstorms and moderate rain in immediate area. Altitude assignment of 5;000 FT per SID set in MCP altitude window. Passing 3;000 FT and after completing After Takeoff Checklist; pilot flying engaged center autopilot. I confirmed FMA annunciations HDG; VNAV SPD and CMD. ATC asked if we could turn to a 270-degree heading; and I turned my attention to the radar display on the ND to assess convective weather to the west of the departure path; pausing momentarily to make the 1;000 FT below assigned altitude callout when passing through 4;000 FT. Captain acknowledged. I then resumed analysis of radar returns on ND as ATC queried us once again regarding the turn to a westbound heading. Shortly thereafter; I checked my altimeter and noted that we were passing 4;900 FT with a rate of climb of 1;400 FPM. [We] crosschecked the Captain's altimeter as climb continued through 5;000 FT at 1;000 plus FPM. [I] noted boxed VNAV ALT on Captain's FMA. [I] verbally announced 'altitude' to Captain as we approached 5;100 FT with VS of 1;000 FPM. Captain continued to monitor autoflight; but did not intervene as autopilot appeared to be reducing pitch angle with VNAV ALT displayed. At 5;200 FT I again announced 'altitude' followed by; 'We're only cleared to five thousand' and prepared to disconnect autopilot and assume control but did not at that time; autopilot remained engaged and finally captured MCP altitude; but not before overshooting our assigned altitude by about 300 FT. Neither ATC nor TCAS indicated any conflicting traffic or loss of separation. After clearing weather; we proceeded on course and resumed climb to cruise altitude with several intermediate level offs due to traffic. Center autopilot remained engaged and functioned normally. Reliability breeds complacency. It is unusual to encounter a situation in which the autoflight system fails to capture an altitude during climb or descent; especially when the appropriate FMA modes are displayed. But if it does happen; each pilot must be prepared to recognize such a malfunction and intervene to prevent an altitude bust and potential loss of separation.

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.