Narrative:

We were cleared to descend from 10000 ft MSL to 7000 ft MSL. The copilot was flying and the autoplt was off. Just below 8000 MSL the approach controller cleared us to turn to a heading of 260 degrees. In the turn the copilot let the aircraft descend to 6600 before catching the altitude deviation. We immediately climbed back to 7000 ft. There was no conflict with other aircraft. I believe the major cause of the deviation was pilot fatigue. The crew had been on duty for over 12 hours commencing the night before. The flight was originally scheduled for 1 hour and 41 mins. However, it could not land at destination due to WX. The crew had to land twice to refuel due to 2 extended periods of holding. Flight time was extended to almost 8 hours since the flight was re-rted to 2 different airports before it could return to the original destination. It would help flight safety if the FAA revised time and duty regulations to reduce the time allowed for continuous duty to 10 hours, especially during middle of the night operations. The deviation might have been prevented if the airplane had been left on autoplt until the final approach. Callback conversation with reporter revealed the following information: the reporter flies the B-757 for a major freight airline. The evening in question was particularly bad with 2 diversion, to different airports, for fuel. The national WX service badly botched the WX forecast at sdf. The reporter took off for sdf after the first diversion because the hourly WX report did not contain the RVR which remained below CAT ii minimums. The crew ran out of water. A friendly vehicle driver took the crew to breakfast or they would not have had any food for over 10 hours. The reporter is now aware of the FAA aviation safety hotline. Nothing illegal was done on this trip, but the reporter would like to see a change in the duty regulations.

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Original NASA ASRS Text

Title: ALTDEV IN DSCNT.

Narrative: WE WERE CLRED TO DSND FROM 10000 FT MSL TO 7000 FT MSL. THE COPLT WAS FLYING AND THE AUTOPLT WAS OFF. JUST BELOW 8000 MSL THE APCH CTLR CLRED US TO TURN TO A HDG OF 260 DEGS. IN THE TURN THE COPLT LET THE ACFT DSND TO 6600 BEFORE CATCHING THE ALTDEV. WE IMMEDIATELY CLBED BACK TO 7000 FT. THERE WAS NO CONFLICT WITH OTHER ACFT. I BELIEVE THE MAJOR CAUSE OF THE DEV WAS PLT FATIGUE. THE CREW HAD BEEN ON DUTY FOR OVER 12 HRS COMMENCING THE NIGHT BEFORE. THE FLT WAS ORIGINALLY SCHEDULED FOR 1 HR AND 41 MINS. HOWEVER, IT COULD NOT LAND AT DEST DUE TO WX. THE CREW HAD TO LAND TWICE TO REFUEL DUE TO 2 EXTENDED PERIODS OF HOLDING. FLT TIME WAS EXTENDED TO ALMOST 8 HRS SINCE THE FLT WAS RE-RTED TO 2 DIFFERENT ARPTS BEFORE IT COULD RETURN TO THE ORIGINAL DEST. IT WOULD HELP FLT SAFETY IF THE FAA REVISED TIME AND DUTY REGS TO REDUCE THE TIME ALLOWED FOR CONTINUOUS DUTY TO 10 HRS, ESPECIALLY DURING MIDDLE OF THE NIGHT OPS. THE DEV MIGHT HAVE BEEN PREVENTED IF THE AIRPLANE HAD BEEN L ON AUTOPLT UNTIL THE FINAL APCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE B-757 FOR A MAJOR FREIGHT AIRLINE. THE EVENING IN QUESTION WAS PARTICULARLY BAD WITH 2 DIVERSION, TO DIFFERENT ARPTS, FOR FUEL. THE NATIONAL WX SVC BADLY BOTCHED THE WX FORECAST AT SDF. THE RPTR TOOK OFF FOR SDF AFTER THE FIRST DIVERSION BECAUSE THE HRLY WX RPT DID NOT CONTAIN THE RVR WHICH REMAINED BELOW CAT II MINIMUMS. THE CREW RAN OUT OF WATER. A FRIENDLY VEHICLE DRIVER TOOK THE CREW TO BREAKFAST OR THEY WOULD NOT HAVE HAD ANY FOOD FOR OVER 10 HRS. THE RPTR IS NOW AWARE OF THE FAA AVIATION SAFETY HOTLINE. NOTHING ILLEGAL WAS DONE ON THIS TRIP, BUT THE RPTR WOULD LIKE TO SEE A CHANGE IN THE DUTY REGS.

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.