Narrative:

We were on a 40 min flight from atl to bna. The copilot was flying. After leveling off at FL260, we were given a crossing restr of FL240 at, I believe, 20 mi northwest of cha. The copilot dialed in FL220 into the altitude alert, and questioned the captain about the altitude we were cleared to. I was copying down the ATIS at this time and preparing the landing data card. The captain had read back the altitude restr of FL240, but apparently did not confirm this altitude with the copilot. The copilot then began his descent to FL220. As we passed through FL230, ATC requested that we level off at FL230. Possible causes: copilot did not hear the altitude assignment, probably due to conversation in the cockpit. The captain didn't hear the copilot question the altitude assignment or misunderstood the question. Either way, there was some miscom between the captain and copilot. I was out of the loop while obtaining the ATIS, however, I should have been paying more attention, especially when I detected some confusion from the copilot concerning the altitude. One question at FL250 would have prevented the deviation. The captain was distraction while using the radar to avoid thunderstorms, so the copilot was flying 'solo' during this deviation. Supplemental information from acn 333513: we had a 13 hour day before. A mechanical delay today. It was our last leg. WX was poor at destination airport.

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Original NASA ASRS Text

Title: ATC FLC MISCOM ON ALT ASSIGNMENT XING RESTR. AFTER CAPT HAD READ BACK THE CORRECT ALT, HE DIDN'T CONFIRM IT WITH THE PF, FO. THE FO SET FL220 IN THE ALT ALERT, BUT THE CAPT AND SO WERE DISTR WITH OTHER COCKPIT DUTIES AND DIDN'T SEE IT. ATC INTERVENED WHEN THE ACFT WAS OBSERVED 1000 FT BELOW ASSIGNED AND ATC REASSIGNED THE PRESENT ALT.

Narrative: WE WERE ON A 40 MIN FLT FROM ATL TO BNA. THE COPLT WAS FLYING. AFTER LEVELING OFF AT FL260, WE WERE GIVEN A XING RESTR OF FL240 AT, I BELIEVE, 20 MI NW OF CHA. THE COPLT DIALED IN FL220 INTO THE ALT ALERT, AND QUESTIONED THE CAPT ABOUT THE ALT WE WERE CLRED TO. I WAS COPYING DOWN THE ATIS AT THIS TIME AND PREPARING THE LNDG DATA CARD. THE CAPT HAD READ BACK THE ALT RESTR OF FL240, BUT APPARENTLY DID NOT CONFIRM THIS ALT WITH THE COPLT. THE COPLT THEN BEGAN HIS DSCNT TO FL220. AS WE PASSED THROUGH FL230, ATC REQUESTED THAT WE LEVEL OFF AT FL230. POSSIBLE CAUSES: COPLT DID NOT HEAR THE ALT ASSIGNMENT, PROBABLY DUE TO CONVERSATION IN THE COCKPIT. THE CAPT DIDN'T HEAR THE COPLT QUESTION THE ALT ASSIGNMENT OR MISUNDERSTOOD THE QUESTION. EITHER WAY, THERE WAS SOME MISCOM BTWN THE CAPT AND COPLT. I WAS OUT OF THE LOOP WHILE OBTAINING THE ATIS, HOWEVER, I SHOULD HAVE BEEN PAYING MORE ATTN, ESPECIALLY WHEN I DETECTED SOME CONFUSION FROM THE COPLT CONCERNING THE ALT. ONE QUESTION AT FL250 WOULD HAVE PREVENTED THE DEV. THE CAPT WAS DISTR WHILE USING THE RADAR TO AVOID TSTMS, SO THE COPLT WAS FLYING 'SOLO' DURING THIS DEV. SUPPLEMENTAL INFO FROM ACN 333513: WE HAD A 13 HR DAY BEFORE. A MECHANICAL DELAY TODAY. IT WAS OUR LAST LEG. WX WAS POOR AT DEST ARPT.

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.