Narrative:

Shead departure to oak; first officer flying; autoplt engaged command mode. Assigned 11000 ft; dialed in mode selector window. Out of 11000 ft; first officer reduced pitch to approximately 500 FPM to accelerate to FMC climb speed. At about 300 KTS and 10300 ft we got moderate chop. First officer increased pitch to slow; pulling up to approximately 3000+ FPM. Although the AFDS went to altitude acquire; I knew (the hgs was my first indication; I'm an hgs flyer) the autoplt would overshoot the leveloff. I disconnected the autoplt (approximately 10600 ft) and manually leveled off using the hgs and retarding the thrust levers. We topped out between 11300 and 11400 ft before leveling at 11000. The departure controller had issued us G-4 traffic at 10 O'clock position; 12500; descending on the arrival; and asked us if we were leveling at 11000 ft. I told him the autoplt had overshot the leveloff; but we were now level at 11000. We did not receive a TCAS TA or RA at any time. Level at 11000 ft; I gave the aircraft back to the first officer; he re-engaged the autoplt and we continued to oak. At cruise I discussed the event with the first officer; explaining that the overshoot was not an autoplt malfunction; but that he had 'asked too much' of the autoplt when he increased the rate of climb so much so close to leveloff altitude; especially without a large power reduction. I apologized for taking the aircraft so suddenly and disconnecting the autoplt; but explained that the hgs gave me the clue that the autoplt was not going to 'hack' the leveloff before he realized that it was going to overshoot. The hgs is golden for situational awareness. The time from the first officer's initial pull-up in response to the chop; to my leveling manually at 11000 ft was quite short.

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Original NASA ASRS Text

Title: B737-300 FLT CREW HAS AN ALTDEV DURING SHEAD DEP FROM LAS.

Narrative: SHEAD DEP TO OAK; FO FLYING; AUTOPLT ENGAGED COMMAND MODE. ASSIGNED 11000 FT; DIALED IN MODE SELECTOR WINDOW. OUT OF 11000 FT; FO REDUCED PITCH TO APPROX 500 FPM TO ACCELERATE TO FMC CLB SPD. AT ABOUT 300 KTS AND 10300 FT WE GOT MODERATE CHOP. FO INCREASED PITCH TO SLOW; PULLING UP TO APPROX 3000+ FPM. ALTHOUGH THE AFDS WENT TO ALT ACQUIRE; I KNEW (THE HGS WAS MY FIRST INDICATION; I'M AN HGS FLYER) THE AUTOPLT WOULD OVERSHOOT THE LEVELOFF. I DISCONNECTED THE AUTOPLT (APPROX 10600 FT) AND MANUALLY LEVELED OFF USING THE HGS AND RETARDING THE THRUST LEVERS. WE TOPPED OUT BTWN 11300 AND 11400 FT BEFORE LEVELING AT 11000. THE DEP CTLR HAD ISSUED US G-4 TFC AT 10 O'CLOCK POS; 12500; DSNDING ON THE ARR; AND ASKED US IF WE WERE LEVELING AT 11000 FT. I TOLD HIM THE AUTOPLT HAD OVERSHOT THE LEVELOFF; BUT WE WERE NOW LEVEL AT 11000. WE DID NOT RECEIVE A TCAS TA OR RA AT ANY TIME. LEVEL AT 11000 FT; I GAVE THE ACFT BACK TO THE FO; HE RE-ENGAGED THE AUTOPLT AND WE CONTINUED TO OAK. AT CRUISE I DISCUSSED THE EVENT WITH THE FO; EXPLAINING THAT THE OVERSHOOT WAS NOT AN AUTOPLT MALFUNCTION; BUT THAT HE HAD 'ASKED TOO MUCH' OF THE AUTOPLT WHEN HE INCREASED THE RATE OF CLB SO MUCH SO CLOSE TO LEVELOFF ALT; ESPECIALLY WITHOUT A LARGE PWR REDUCTION. I APOLOGIZED FOR TAKING THE ACFT SO SUDDENLY AND DISCONNECTING THE AUTOPLT; BUT EXPLAINED THAT THE HGS GAVE ME THE CLUE THAT THE AUTOPLT WAS NOT GOING TO 'HACK' THE LEVELOFF BEFORE HE REALIZED THAT IT WAS GOING TO OVERSHOOT. THE HGS IS GOLDEN FOR SITUATIONAL AWARENESS. THE TIME FROM THE FO'S INITIAL PULL-UP IN RESPONSE TO THE CHOP; TO MY LEVELING MANUALLY AT 11000 FT WAS QUITE SHORT.

Data retrieved from NASA's ASRS site as of January 2009 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.