Narrative:

Received clearance from approach to descend from 14000 ft to 13000 ft and heading change (I believe). I announced 13000 ft while setting altitude alerter per SOP. First officer (PF) started descent and I went head-down to tune/identify radios for approach. I looked up as aircraft was descending through 12700 ft. I called 'altitude' and started to pull back on yoke. First officer was sure I had misset altitude alerter and was hesitant to climb. I insisted he climb and verified assigned altitude with ATC, who confirmed 13000 ft but reclred us to 11000 ft. Primary cause of this event was first officer's fatigue due to minimum rest layover and poor night's sleep. Contributing to this was the 2 hours we spent taxiing for deicing in snowstorm. The so and I were both aware of the first officer's less than normal stellar performance and were backing him up more than usual (but obviously not enough). Also contributing was my failure to get a positive confirmation from the first officer that he got the 13000 ft clearance (also SOP). Though not always possible in the real world, the last 1000 ft of a climb/descent is not a good time to go heads-down for any reason. Supplemental information from acn 326590: we had a 9 hour 6 mins duty day with a 3 hour break before the last leg to mdw with a block of 1 hour 26 mins. Myself, I only received 6 hours of sleep that first night. Personal thoughts: I require at least 8 hours of sleep, not unwind time on days off. It is physically impossible to receive that kind of rest on anything less than 12 hours of rest on a layover. Minimum rest needs to be bumped up now. I am sick, mostly tired of averaging 6 hours of sleep on short overnights. Drugs and alcohol are not the real villain, lack of rest is.

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Original NASA ASRS Text

Title: CAPT AND SO NOTICE ALTDEV ON DSCNT. FO FATIGUE THE APPARENT PROB.

Narrative: RECEIVED CLRNC FROM APCH TO DSND FROM 14000 FT TO 13000 FT AND HDG CHANGE (I BELIEVE). I ANNOUNCED 13000 FT WHILE SETTING ALT ALERTER PER SOP. FO (PF) STARTED DSCNT AND I WENT HEAD-DOWN TO TUNE/IDENT RADIOS FOR APCH. I LOOKED UP AS ACFT WAS DSNDING THROUGH 12700 FT. I CALLED 'ALT' AND STARTED TO PULL BACK ON YOKE. FO WAS SURE I HAD MISSET ALT ALERTER AND WAS HESITANT TO CLB. I INSISTED HE CLB AND VERIFIED ASSIGNED ALT WITH ATC, WHO CONFIRMED 13000 FT BUT RECLRED US TO 11000 FT. PRIMARY CAUSE OF THIS EVENT WAS FO'S FATIGUE DUE TO MINIMUM REST LAYOVER AND POOR NIGHT'S SLEEP. CONTRIBUTING TO THIS WAS THE 2 HRS WE SPENT TAXIING FOR DEICING IN SNOWSTORM. THE SO AND I WERE BOTH AWARE OF THE FO'S LESS THAN NORMAL STELLAR PERFORMANCE AND WERE BACKING HIM UP MORE THAN USUAL (BUT OBVIOUSLY NOT ENOUGH). ALSO CONTRIBUTING WAS MY FAILURE TO GET A POSITIVE CONFIRMATION FROM THE FO THAT HE GOT THE 13000 FT CLRNC (ALSO SOP). THOUGH NOT ALWAYS POSSIBLE IN THE REAL WORLD, THE LAST 1000 FT OF A CLB/DSCNT IS NOT A GOOD TIME TO GO HEADS-DOWN FOR ANY REASON. SUPPLEMENTAL INFO FROM ACN 326590: WE HAD A 9 HR 6 MINS DUTY DAY WITH A 3 HR BREAK BEFORE THE LAST LEG TO MDW WITH A BLOCK OF 1 HR 26 MINS. MYSELF, I ONLY RECEIVED 6 HRS OF SLEEP THAT FIRST NIGHT. PERSONAL THOUGHTS: I REQUIRE AT LEAST 8 HRS OF SLEEP, NOT UNWIND TIME ON DAYS OFF. IT IS PHYSICALLY IMPOSSIBLE TO RECEIVE THAT KIND OF REST ON ANYTHING LESS THAN 12 HRS OF REST ON A LAYOVER. MINIMUM REST NEEDS TO BE BUMPED UP NOW. I AM SICK, MOSTLY TIRED OF AVERAGING 6 HRS OF SLEEP ON SHORT OVERNIGHTS. DRUGS AND ALCOHOL ARE NOT THE REAL VILLAIN, LACK OF REST IS.

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.