Date: 201410
Local time of day: 1201-1800
Location: EGLL.Airport, FO
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
ATC / advisory: Tower EGLL
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Human factors: Workload; Situational Awareness; Fatigue; Distraction
Second reporter function: Pilot Not Flying; Captain
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: On landing at [EGLL]; I was pilot flying (PF) flying the ILS 27L in VMC conditions. We were not rushed; I was configuring the aircraft for landing; but noticed that the power setting did not seem right to me - when I set normal approach power; I was gaining airspeed. I was struggling with power management from the FAF in.Somewhere below 500 ft AGL; we got the 'too low; flaps' aural warning; and it wasn't until then that I realized I had never called for; and we had never set our final flaps; I had just stopped at gear down; flaps 20.  The Captain immediately selected flaps 25; and we landed uneventfully at flaps 25.I would say fatigue was definitely a factor. I did not feel sleepy; but after being up all night we were given 10 minutes of holding on the arrival and were in a higher-than-normal workload situation during the time leading up to the approach. I felt that I was fixating on speed control without even realizing that I was not getting the aircraft fully configured by 1000 ft AGL.I apologized to my crew mates after gate arrival; and the Captain stated; 'well; there were three of us up here'.By way of prevention; I can only state that I will be more aware of where I am in the landing checklist in order to prevent an event like this from occurring in the future.[Company representative] debriefed me on the event [the next day] at great length; with the outcome being my understanding of the absolute necessity of executing a go around no matter what if the aircraft is not stabilized by 1000 ft. Another causal factor in this event was distraction; prior to departure I was made aware of a family crisis unfolding that was a stressor to me; but I decided to 'complete the mission'. In retrospect; the smartest and safest course of action on my part should have been to have myself removed from the sequence to deal with family issues.


Second narrative: First Officer's leg; before landing checklist was not completed by 1000 ft. This was due to ATC instructing us to slow while looking for heavy jet we were following. Had a configuration warning; looked at flap handle and they were at 20. I had to make a quick decision either configure to flaps 25 or go around; opted to configure since we had already held inbound.


Synopsis: B767-300ER international flight crew reported they failed to select final flaps in a timely manner creating an unstabilized approach scenario; and they then failed to execute a go-around. Fatigue was cited as a factor by the pilot flying.