Narrative:

Having just leveled off at the cleared cruise altitude of 11000' the PF (first officer) engaged the autoplt and altitude hold. The aircraft was accelerating from 280 to 320 KIAS. During a brief moment of inattn (re-shuffling landing and approach charts for the short leg between ont and san), the altitude hold disengaged, followed immediatley by autoplt disengagement. The aircraft pitched up to an indicated altitude of 11320' before either the first officer or myself could correct the unscheduled excursion. ATC made no comment at the time of the incident, and subsequent phone calls to the approach/departure centers involved indicated no problem had been created by the sudden altitude excursion. The autoplt was written up for maintenance action on our arrival at san. For my crew, this incident highlighted the problems of deep seated fatigue form cumulative periods of long duty and flight hours. The incident occurred on the past night of three successive duty periods of 13 1/2 hours each with 10 1/2 hours rest breaks between. During each duty period we flew 4 legs for a total of 7 1/2 flight hours (all night). The problems of flying on the backside of the clock needs to be addressed in the FARS. This is of great concern to night freight pilots and we need the support of the FAA. Callback conversation with reporter revealed the following: reporter gave general discussion on the problems of cargo operation and the back side of the clock.

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Original NASA ASRS Text

Title: ALTITUDE DEVIATION. AUTOPLT MALFUNCTION.

Narrative: HAVING JUST LEVELED OFF AT THE CLRED CRUISE ALT OF 11000' THE PF (F/O) ENGAGED THE AUTOPLT AND ALT HOLD. THE ACFT WAS ACCELERATING FROM 280 TO 320 KIAS. DURING A BRIEF MOMENT OF INATTN (RE-SHUFFLING LNDG AND APCH CHARTS FOR THE SHORT LEG BTWN ONT AND SAN), THE ALT HOLD DISENGAGED, FOLLOWED IMMEDIATLEY BY AUTOPLT DISENGAGEMENT. THE ACFT PITCHED UP TO AN INDICATED ALT OF 11320' BEFORE EITHER THE F/O OR MYSELF COULD CORRECT THE UNSCHEDULED EXCURSION. ATC MADE NO COMMENT AT THE TIME OF THE INCIDENT, AND SUBSEQUENT PHONE CALLS TO THE APCH/DEP CENTERS INVOLVED INDICATED NO PROB HAD BEEN CREATED BY THE SUDDEN ALT EXCURSION. THE AUTOPLT WAS WRITTEN UP FOR MAINT ACTION ON OUR ARR AT SAN. FOR MY CREW, THIS INCIDENT HIGHLIGHTED THE PROBS OF DEEP SEATED FATIGUE FORM CUMULATIVE PERIODS OF LONG DUTY AND FLT HOURS. THE INCIDENT OCCURRED ON THE PAST NIGHT OF THREE SUCCESSIVE DUTY PERIODS OF 13 1/2 HOURS EACH WITH 10 1/2 HOURS REST BREAKS BTWN. DURING EACH DUTY PERIOD WE FLEW 4 LEGS FOR A TOTAL OF 7 1/2 FLT HOURS (ALL NIGHT). THE PROBS OF FLYING ON THE BACKSIDE OF THE CLOCK NEEDS TO BE ADDRESSED IN THE FARS. THIS IS OF GREAT CONCERN TO NIGHT FREIGHT PLTS AND WE NEED THE SUPPORT OF THE FAA. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR GAVE GENERAL DISCUSSION ON THE PROBS OF CARGO OPERATION AND THE BACK SIDE OF THE CLOCK.

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.