Narrative:

The flight was conducted in actual IMC from mdt to abe. Total en route time was 18 mins. On climb out, we were assigned an altitude of 7000 ft. I (captain) was the PF. At 7000 ft, I saw that the aircraft was still climbing and made an immediate correction, but we deviated above, then below the assigned altitude, before stabilizing at 7000 ft. The first officer reported to ATC that we were experiencing a problem with the autoplt and were correcting back to altitude. I determined that the reason the aircraft did not capture the altitude was because it was not in the command mode, but the control wheel steering mode at the time of leveloff. I ensured that the autoplt was engaged in the command mode and the rest of the flight was conducted in a normal fashion. On the ground in abe, I reviewed the flight and concluded the most likely cause of the altitude deviation was due to a 'switchology' error on my part (ie, I thought I had selected the command mode, but in fact had not). Contributing factors include high workload associated with a short flight conducted in IMC and concluding with an ILS at destination. The runway in use at mdt was runway 13 and the landing runway in abe was runway 6 which further compressed the available time. Also, the pressurization was operated in the standby mode because of a maintenance carryover and added to the workload. In conclusion, the error occurred because I was evidently distraction by another event and was not concentrating on the task at hand. I will try to exercise more vigilance in the future.

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Original NASA ASRS Text

Title: B737-300 CREW HAD ALT OVERSHOOT AND UNDERSHOOT BECAUSE AUTOPLT WAS NOT IN THE CORRECT MODE FOR AUTO LEVELOFF IN ZNY CLASS E AIRSPACE.

Narrative: THE FLT WAS CONDUCTED IN ACTUAL IMC FROM MDT TO ABE. TOTAL ENRTE TIME WAS 18 MINS. ON CLBOUT, WE WERE ASSIGNED AN ALT OF 7000 FT. I (CAPT) WAS THE PF. AT 7000 FT, I SAW THAT THE ACFT WAS STILL CLBING AND MADE AN IMMEDIATE CORRECTION, BUT WE DEVIATED ABOVE, THEN BELOW THE ASSIGNED ALT, BEFORE STABILIZING AT 7000 FT. THE FO RPTED TO ATC THAT WE WERE EXPERIENCING A PROB WITH THE AUTOPLT AND WERE CORRECTING BACK TO ALT. I DETERMINED THAT THE REASON THE ACFT DID NOT CAPTURE THE ALT WAS BECAUSE IT WAS NOT IN THE COMMAND MODE, BUT THE CTL WHEEL STEERING MODE AT THE TIME OF LEVELOFF. I ENSURED THAT THE AUTOPLT WAS ENGAGED IN THE COMMAND MODE AND THE REST OF THE FLT WAS CONDUCTED IN A NORMAL FASHION. ON THE GND IN ABE, I REVIEWED THE FLT AND CONCLUDED THE MOST LIKELY CAUSE OF THE ALTDEV WAS DUE TO A 'SWITCHOLOGY' ERROR ON MY PART (IE, I THOUGHT I HAD SELECTED THE COMMAND MODE, BUT IN FACT HAD NOT). CONTRIBUTING FACTORS INCLUDE HIGH WORKLOAD ASSOCIATED WITH A SHORT FLT CONDUCTED IN IMC AND CONCLUDING WITH AN ILS AT DEST. THE RWY IN USE AT MDT WAS RWY 13 AND THE LNDG RWY IN ABE WAS RWY 6 WHICH FURTHER COMPRESSED THE AVAILABLE TIME. ALSO, THE PRESSURIZATION WAS OPERATED IN THE STANDBY MODE BECAUSE OF A MAINT CARRYOVER AND ADDED TO THE WORKLOAD. IN CONCLUSION, THE ERROR OCCURRED BECAUSE I WAS EVIDENTLY DISTR BY ANOTHER EVENT AND WAS NOT CONCENTRATING ON THE TASK AT HAND. I WILL TRY TO EXERCISE MORE VIGILANCE IN THE FUTURE.

Data retrieved from NASA's ASRS site as of July 2007 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.