Narrative:

I fly for a commuter airline, which has what many pilots believe to be an abusive schedule. I had already flown 45 hours block within the preceeding 7 days of work. This particular day was the 4TH day of my 5 day work week. I had just come off of reduced rest the night before, and was on duty for 13 1/2 hours. This day in detroit I had already been on duty since xa:15 and it was now xl:00 and I still had 2 more legs to go to get to my overnight station at xa:30. This crew was not very well rested. At the time of the altitude deviation, detroit ATC was very busy and putting aircraft on 25 mi final approachs. We were told to descend from 11000' MSL to 6000'. We left 11000' as we were abeam the T/D point for runway 21R on a right downwind. When we started descent, the PNF started to do a descent check out of about 8000'. When he was done with the checklist he left the #1 radio (ATC) to call company on #2 radio. While he was 'out of the loop' I was looking outside for traffic in the haze. When I looked back in the cockpit I noticed my altimeter read 5600'. When the other pilot said he was back with me I asked him to verify altitude. He said 6000'. I immediately pitched up added power and was level at 6000' in about 5 seconds. Just when I started up the controller asked me about my altitude, and we replied 6000' which we were soon level at. There was no conflict in traffic or danger.

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Original NASA ASRS Text

Title: COMMUTER LTT ALT DEVIATION OVERSHOT DURING DESCENT.

Narrative: I FLY FOR A COMMUTER AIRLINE, WHICH HAS WHAT MANY PLTS BELIEVE TO BE AN ABUSIVE SCHEDULE. I HAD ALREADY FLOWN 45 HRS BLOCK WITHIN THE PRECEEDING 7 DAYS OF WORK. THIS PARTICULAR DAY WAS THE 4TH DAY OF MY 5 DAY WORK WK. I HAD JUST COME OFF OF REDUCED REST THE NIGHT BEFORE, AND WAS ON DUTY FOR 13 1/2 HRS. THIS DAY IN DETROIT I HAD ALREADY BEEN ON DUTY SINCE XA:15 AND IT WAS NOW XL:00 AND I STILL HAD 2 MORE LEGS TO GO TO GET TO MY OVERNIGHT STATION AT XA:30. THIS CREW WAS NOT VERY WELL RESTED. AT THE TIME OF THE ALT DEV, DETROIT ATC WAS VERY BUSY AND PUTTING ACFT ON 25 MI FINAL APCHS. WE WERE TOLD TO DSND FROM 11000' MSL TO 6000'. WE L 11000' AS WE WERE ABEAM THE T/D POINT FOR RWY 21R ON A R DOWNWIND. WHEN WE STARTED DSNT, THE PNF STARTED TO DO A DSNT CHK OUT OF ABOUT 8000'. WHEN HE WAS DONE WITH THE CHKLIST HE L THE #1 RADIO (ATC) TO CALL COMPANY ON #2 RADIO. WHILE HE WAS 'OUT OF THE LOOP' I WAS LOOKING OUTSIDE FOR TFC IN THE HAZE. WHEN I LOOKED BACK IN THE COCKPIT I NOTICED MY ALTIMETER READ 5600'. WHEN THE OTHER PLT SAID HE WAS BACK WITH ME I ASKED HIM TO VERIFY ALT. HE SAID 6000'. I IMMEDIATELY PITCHED UP ADDED PWR AND WAS LEVEL AT 6000' IN ABOUT 5 SECS. JUST WHEN I STARTED UP THE CTLR ASKED ME ABOUT MY ALT, AND WE REPLIED 6000' WHICH WE WERE SOON LEVEL AT. THERE WAS NO CONFLICT IN TFC OR DANGER.

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.