Narrative:

Copilot flying, we were cleared to FL240, descending into sdf. First officer selected altitude hold at FL240 (autoplt on) but aircraft continued to descend to FL237. I told him to get back to FL240, but he was attempting to get us back on the autoplt. I took over the aircraft manually, clicking off the autoplt and climbed us back to FL240. We were not at FL237 more than a maximum of 30 seconds. ZID called us to ask about altitude, as we leveled at FL240, then informed us that he showed us level at FL240. I do not know of any traffic problems. I expected the first officer to take control of the airplane manually, when I told him to climb back to FL240. I could have communicated better, by saying climb back to assigned flight level manually. We discussed this afterwards.

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Original NASA ASRS Text

Title: A DSNDING DC8 FREIGHTER OVERSHOT ITS ALT. THE FO WAS SLOW IN MAKING THE TYPE RECOVERY THAT THE CAPT EXPECTED.

Narrative: COPLT FLYING, WE WERE CLRED TO FL240, DSNDING INTO SDF. FO SELECTED ALT HOLD AT FL240 (AUTOPLT ON) BUT ACFT CONTINUED TO DSND TO FL237. I TOLD HIM TO GET BACK TO FL240, BUT HE WAS ATTEMPTING TO GET US BACK ON THE AUTOPLT. I TOOK OVER THE ACFT MANUALLY, CLICKING OFF THE AUTOPLT AND CLBED US BACK TO FL240. WE WERE NOT AT FL237 MORE THAN A MAX OF 30 SECONDS. ZID CALLED US TO ASK ABOUT ALT, AS WE LEVELED AT FL240, THEN INFORMED US THAT HE SHOWED US LEVEL AT FL240. I DO NOT KNOW OF ANY TFC PROBS. I EXPECTED THE FO TO TAKE CTL OF THE AIRPLANE MANUALLY, WHEN I TOLD HIM TO CLB BACK TO FL240. I COULD HAVE COMMUNICATED BETTER, BY SAYING CLB BACK TO ASSIGNED FLT LEVEL MANUALLY. WE DISCUSSED THIS AFTERWARDS.

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.