Narrative:

I was being vectored for an ILS approach runway 13, at mdt in IMC conditions. I was cleared for descent from 4000 ft to 3000 ft. I descended to 2700-2650 ft before climbing back to 3000 ft. At 2700 ft the altitude chime sounded. At 4000 ft, the captain dialed in 3000 ft in the altitude alerter and because of my descent below 4000 ft the altitude chime did not sound a 1000 ft warning. This is something I'm used to hearing. I had been awake since XA00 and had started my trip in salt lake city. I was well within duty and flight time limits, but I was tired. Upon nearing my final landing of the day, I got complacent, maybe even daydreaming. In any case, I let my altitude slip, and corrected it with no adverse affects. As I've told myself and others many times before, when you're tired you must be more alert and don't let complacency enter the cockpit.

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Original NASA ASRS Text

Title: ALTDEV ON DSCNT.

Narrative: I WAS BEING VECTORED FOR AN ILS APCH RWY 13, AT MDT IN IMC CONDITIONS. I WAS CLRED FOR DSCNT FROM 4000 FT TO 3000 FT. I DSNDED TO 2700-2650 FT BEFORE CLBING BACK TO 3000 FT. AT 2700 FT THE ALT CHIME SOUNDED. AT 4000 FT, THE CAPT DIALED IN 3000 FT IN THE ALT ALERTER AND BECAUSE OF MY DSCNT BELOW 4000 FT THE ALT CHIME DID NOT SOUND A 1000 FT WARNING. THIS IS SOMETHING I'M USED TO HEARING. I HAD BEEN AWAKE SINCE XA00 AND HAD STARTED MY TRIP IN SALT LAKE CITY. I WAS WELL WITHIN DUTY AND FLT TIME LIMITS, BUT I WAS TIRED. UPON NEARING MY FINAL LNDG OF THE DAY, I GOT COMPLACENT, MAYBE EVEN DAYDREAMING. IN ANY CASE, I LET MY ALT SLIP, AND CORRECTED IT WITH NO ADVERSE AFFECTS. AS I'VE TOLD MYSELF AND OTHERS MANY TIMES BEFORE, WHEN YOU'RE TIRED YOU MUST BE MORE ALERT AND DON'T LET COMPLACENCY ENTER THE COCKPIT.

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.