Narrative:

We descended to various step down altitudes on approach based on DME. During the final step down (1600 ft - 700 ft) the approach controller got an altitude warning on us and notified us we were too low. Our DME had been in 'hold' off the sea VOR by mistake, and not the bfi localizer as they should have been. When the controller called we were just breaking out, we stopped descent, got the field in sight and landed normally. Both pilots had been on duty for +12 hours and dealing with WX, ice, etc. Fatigue was a factor. My reliance on the other pilot to set up the approach was also a factor. We fly together often and are both good instrument pilots (most of the time)! Thank you ATC for having this altitude warning capability -- we are embarrassed and wiser -- but very much alive!

Google
 

Original NASA ASRS Text

Title: CORP FLC LOCKS DME ON WRONG FACILITY. APCH CTLR ISSUES LOW ALT WARNING.

Narrative: WE DSNDED TO VARIOUS STEP DOWN ALTS ON APCH BASED ON DME. DURING THE FINAL STEP DOWN (1600 FT - 700 FT) THE APCH CTLR GOT AN ALT WARNING ON US AND NOTIFIED US WE WERE TOO LOW. OUR DME HAD BEEN IN 'HOLD' OFF THE SEA VOR BY MISTAKE, AND NOT THE BFI LOC AS THEY SHOULD HAVE BEEN. WHEN THE CTLR CALLED WE WERE JUST BREAKING OUT, WE STOPPED DSCNT, GOT THE FIELD IN SIGHT AND LANDED NORMALLY. BOTH PLTS HAD BEEN ON DUTY FOR +12 HRS AND DEALING WITH WX, ICE, ETC. FATIGUE WAS A FACTOR. MY RELIANCE ON THE OTHER PLT TO SET UP THE APCH WAS ALSO A FACTOR. WE FLY TOGETHER OFTEN AND ARE BOTH GOOD INST PLTS (MOST OF THE TIME)! THANK YOU ATC FOR HAVING THIS ALT WARNING CAPABILITY -- WE ARE EMBARRASSED AND WISER -- BUT VERY MUCH ALIVE!

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.