Date: 201505
Flight conditions: VMC
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Reporter organization: Air Carrier
Reporter function: First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Fatigue
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Observer
When detected: In-flight
Result: Flight Crew Became Reoriented

Narrative: Flight XXX was a flight from ZZZ to ZZZ1 on a Boeing 777 with a flight crew consisting of a Captain; First Officer; and International Relief Officer. I was the respective First Officer on this flight. We had an additional crew member from the FAA riding the jumpseat for observation. There was nothing notable about the enroute portion of the flight. There were three breaks scheduled for the respective crew members. The IRO took the first break; I took the second break; and the Captain took the third break. The breaks were just a little under two hours. Upon returning from my break I was briefed by the Captain before he took his break and we proceeded normally as the IRO exchanged seats with the Captain. The FAA Observer engaged the IRO and myself in conversation from the middle jumpseat much as he did when the Captain and I were on the flight deck while the IRO was taking his break. As we somewhat ran out of things to talk about; the FAA Observer moved from the center jumpseat to the jumpseat on the right. There wasn't much conversation for an extended period of time between any of us. At some point I inadvertently dozed off what felt like to be a very short period of time. I was awaken by the FAA Observer. The flight proceeded normally after that point.It was brought to my attention that the FAA Observer allegedly felt that I was asleep for ten minutes or more. I find it odd that if I was indeed asleep for that period of time and that neither the FAA Observer nor the IRO said anything to me to wake me up. How could the FAA Observer being an additional crew member recognize that I was asleep and then proceed to allow me to remain in such a state? I question his time frame on his allegations because of this. Nonetheless; I should have been alerted immediately by the IRO and/or the FAA Observer if either one of them saw that I had indeed fallen asleep. I openly admit that I did doze off; and it was not intentional. There is one more item that I find odd. The FAA Observer never did debrief me or have any discussion with me after the flight regarding sleeping.After analyzing the event and trying to determine the contributing factors as to why it happened there were some threats that stood out. First; I did not sleep well during my pre-departure nap in Honolulu. I had planned for two hours and thirty minutes; but at most I may have slept thirty minutes. Secondly; the breaks are very short on the HNL-ZZZ leg. Finally; this was my first trip on this model of 777. Up until that point all of my flights have been on a different 777 model. I feel that the rest facilities on the other model are superior to that on [this model we were flying this day]. I have become accustomed to having a bunk or a lie flat business class seat. The rest facility in [this model] is a just a seat that somewhat reclines. I found it very uncomfortable and noisy based on its location. Needless to say I didn't rest very well on my short break. I had another ZZZ trip just after this one and to mitigate the possibility of not getting the proper rest in the rest seat I gave myself a four hour period to take my pre-departure nap in ZZZ to get more rest at the hotel.




Synopsis: B-777 First Officer fell asleep due to fatigue.