Widebody Transport
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 195; Flight Crew Total 17527; Flight Crew Type 493
Workload; Confusion; Fatigue; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Became Reoriented
Human Factors
During descent into Dulles new ATIS showed a change from ILS 1R to visual 1R and ILS out of service. We changed the brief to 'visual backed up with RNP Y 1R' and reviewed MCP actions ie; LVSAFE for FD guidance on the visual approach. Turning base a few miles outside the FAF I asked to First officer (FO) to 'un-park' the ILS; believing I would get ghost GS diamonds to help with intercept of final approach. I soon found this was a mistake. Prior to un-parking ILS we had correct 'RNAV RNP Y 1R in top left of PFD; as soon as we un-parked the ILS it became ILS 1R. This confused me and in hopes of bring back guidance I asked the FO to reload the RNP approach. This set off a chain of more problems. I delayed descent while the FO programmed the FMC. The FO was a little overloaded with this request as we were in the turn configuring and sent to the Tower frequency all at the same time. The out of service ILS also gave us a false GS saying were low when were not. I quickly got behind the airplane and was rushing to slow and configure in a tailwind that I did not consider at the time. I did verbalize that if we were not stable at 500 feet we would go around. I believe we missed the 1000 foot call; and at 500 feet were on the PAPI configured and stable. The bottom line was it was a poorly flown approach. We debriefed the event at the gate. The takeaways were that: at 2000 feet outside the FAF when we lost approach guidance there were two better options. I could have turned off all FD's thereby putting the throttles in to SPEED MODE and continued the visual approach. The other option was to stay level at 2000 feet and ask the Tower just to vector us around for another approach. Either of these options would have lessened the workload and kept me from being so far behind the airplane. My decision to continue as I did may not have caused an unwanted aircraft state but it certainly did cause an unwanted crew state. I overloaded the FO and was behind the airplane and not totally situationally aware. The factors involved do include the type of flying we do and all that goes with it (long flight; wrong side of clock; poor sleep); but the bottom line is I made a poor decision to continue in the manner we did.
Air carrier Captain reported high workload led to an unstabilized approach to IAD. Reporter cited fatigue as contributing to the event.