Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 139; Flight Crew Total 18200; Flight Crew Type 8778
Fatigue; Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Human Factors
I began my day at XA00 local as a short call reserve. At approximately XB00 Crew Scheduling called and assigned a XE00 departure from ZZZ to EIDW. About 4 hours into the flight; or about XI00 body-clock time; I felt extremely fatigued and struggled to remain awake for the next 3 hours of the flight. The First Officer admitted to also feeling very fatigued. On arrival into EIDW I missed several radio calls and was generally not alert. This flight is unaugmented and departs every night from ZZZ at XE00. This flight and the ZZZ - ZZZ1 flight; also unaugmented and departing at XE30; are routinely in open time because no one wants to fly them because of the fatigue factors involved. They are therefore almost always flown by reserves; many of whom are called out; as I was; from short call status. I think this practice of flying late night flights that impinges on the WOCL (Window of Circadian Low); unaugmented; in an international theater is unsafe and should not be allowed for safety reasons.
Air carrier Captain reported experiencing extreme fatigue and missed radio calls during a late night into early morning flight.