Narrative:

We were delayed 5 hours due to aircraft maintenance. When we taxied out for departure we extended our duty day as we were probably going to exceed the far 117 duty limit of 19 hours. Shortly before takeoff a pack failed requiring us to return to the gate for maintenance action. That took an additional hour to resolve. Just before we were to leave the gate the second time the captain asked each of us if we were still willing to continue. We each said yes. By the time we were ready for the descent/approach and landing in asia I was exhausted and having difficulty with my concentration; situational awareness and listening ability. The weather was VFR and the flight had been smooth with no passenger issues or aircraft maintenance issues. I was flying relief so I was not at the controls during the descent and landing and had been up for the last 7 hours before landing. However; I was impaired due to being on duty for 21 hours at the time of landing. The far limit for 4 pilots and a class 1 rest facility is 19 hours and we extended for an additional 2 hours - I will not ever do it again because; I was well rested before the day began and rested well for 6+ hours in the bunk and considered myself unsafe at the time of landing. In my opinion; the ability to extend an far 117 duty day puts pilots in a terrible position of having to forecast their condition 20+ hours in the future which cannot be done with any reason of certainty. Given my experience; I will not do it again in the future. If we had had to deal with poor weather at the destination or a major system malfunction of the airplane the chance for compounding critical pilot errors would make the operation totally unsafe.

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Original NASA ASRS Text

Title: An International Relief Officer reported extending his duty day beyond 19 hours as allowed by FAR 117 for a four pilot crew; then prior to landing recognizing his extreme fatigue.

Narrative: We were delayed 5 hours due to aircraft maintenance. When we taxied out for departure we extended our duty day as we were probably going to exceed the FAR 117 duty limit of 19 hours. Shortly before takeoff a pack failed requiring us to return to the gate for maintenance action. That took an additional hour to resolve. Just before we were to leave the gate the second time the Captain asked each of us if we were still willing to continue. We each said yes. By the time we were ready for the descent/approach and landing in Asia I was exhausted and having difficulty with my concentration; situational awareness and listening ability. The weather was VFR and the flight had been smooth with no passenger issues or aircraft maintenance issues. I was flying relief so I was not at the controls during the descent and landing and had been up for the last 7 hours before landing. However; I was impaired due to being on duty for 21 hours at the time of landing. The FAR limit for 4 pilots and a class 1 rest facility is 19 hours and we extended for an additional 2 hours - I will not ever do it again because; I was well rested before the day began and rested well for 6+ hours in the bunk and considered myself unsafe at the time of landing. In my opinion; the ability to extend an FAR 117 duty day puts pilots in a terrible position of having to forecast their condition 20+ hours in the future which cannot be done with any reason of certainty. Given my experience; I will not do it again in the future. If we had had to deal with poor weather at the destination or a major system malfunction of the airplane the chance for compounding critical pilot errors would make the operation totally unsafe.

Data retrieved from NASA's ASRS site 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.